CloudLinux AlmaLinux OS 9 Security Technical Implementation Guide

Operating system management includes the ability to control the number of users and user sessions that use an operating system. Limiting the number of allowed users and sessions per user is helpful in reducing the risks related to denial-of-service (DoS) attacks.

This requirement addresses concurrent sessions for information system accounts and does not address concurrent sessions by single users via multiple system accounts. The maximum number of concurrent sessions should be defined based upon mission needs and the operational environment for each system.

Setting the screensaver mode to blank-only conceals the contents of the display from passersby.

A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to logout because of the temporary nature of the absence.

Terminating an idle interactive command shell user session within a short time period reduces the window of opportunity for unauthorized personnel to take control of it when left unattended in a virtual terminal or physical console.

Declaring $TMOUT as read-only means the user cannot override the setting.

Satisfies: SRG-OS-000029-GPOS-00010, SRG-OS-000281-GPOS-00111, SRG-OS-000163-GPOS-00072

A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence.

The session lock is implemented at the point where session activity can be determined.

Regardless of where the session lock is determined and implemented, once invoked, the session lock must remain in place until the user re-authenticates. No other activity aside from re-authentication must unlock the system.

Remote access services, such as those providing remote access to network devices and information systems, which lack automated monitoring capabilities, increase risk, and make remote user access management difficult at best.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Automated monitoring of remote access sessions allows organizations to detect cyber attacks and also ensure ongoing compliance with remote access policies by auditing connection activities of remote access capabilities, such as Remote Desktop Protocol (RDP), on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets).

Monitoring of remote access can be used to spot attacks such as brute-force authentication attempts and denial-of-service (DoS) attacks.

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash.

AlmaLinux OS 9 incorporates systemwide crypto policies by default. The SSH configuration file has no effect on the ciphers, MACs, or algorithms unless specifically defined in the /etc/sysconfig/sshd file. The employed algorithms can be viewed in the /etc/crypto-policies/back-ends/opensshserver.config file.

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash.

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash.

Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Encryption provides a means to secure the remote connection to prevent unauthorized access to the data traversing the remote access connection (e.g., RDP), thereby providing a degree of confidentiality. The encryption strength of a mechanism is selected based on the security categorization of the information.

Session key regeneration limits the chances of a session key becoming compromised.

Overriding the system crypto policy makes the behavior of the Libreswan service violate expectations and makes the system configuration more fragmented.

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash.

The employed algorithms can be viewed in the /etc/crypto-policies/back-ends/openssl.config file.

FIPS 140-3 validated packages are available from TuxCare.

The original community packages must be replaced with the versions that have gone through the CMVP.

Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000478-GPOS-00223, SRG-OS-000396-GPOS-00176, SRG-OS-000125-GPOS-00065

Temporary accounts are accounts created during a time of need when prompt action requires bypassing the normal account creation authorization process – such as during incident response.

If these temporary accounts are left enabled (and may have elevated permissions via sudo, group membership or SSH keys) and are not automatically expired or manually removed, the security posture of the system will be degraded and left vulnerable to insider threat.

Temporary accounts are not the same as "last resort" or "break glass" emergency accounts which are local system accounts to be used by and maintained by authorized system administrators when standard remote access/authentication is unavailable. Emergency accounts are not subject to removal or expiration requirements.

Satisfies: SRG-OS-000002-GPOS-00002, SRG-OS-000123-GPOS-00064

Audit records provide a means to investigate events related to a security incident. Insufficient audit coverage will make identifying those responsible challenging or impossible.

This auditd policy will watch for and alert the system administrators regarding any modifications to the "/etc/group" file such as adding/removing/disabling groups.

Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221

Audit records provide a means to investigate events related to a security incident. Insufficient audit coverage will make identifying those responsible challenging or impossible.

This auditd policy will watch for and alert the system administrators regarding any modifications to the "/etc/security/opasswd" file such as adding/removing/disabling users.

Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221

Audit records provide a means to investigate events related to a security incident. Insufficient audit coverage will make identifying those responsible challenging or impossible.

This auditd policy will watch for and alert the system administrators regarding any modifications to the "/etc/shadow" file such as adding/removing/disabling users.

Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221

This requirement prevents attackers with physical access from easily bypassing security on the machine and gaining root access.

Such accesses are further prevented by configuring the bootloader password.

Having a nondefault grub superuser username makes password-guessing attacks less effective.

A locally logged-on user who presses Ctrl-Alt-Delete in quick succession when at the console can reboot the system.

If accidentally pressed, as could happen in the case of a mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot.

In a graphical user environment, risk of unintentional reboot from the Ctrl-Alt-Delete sequence is reduced because the user will be prompted before any action is taken.

"sudo" is a program designed to allow a system administrator to give limited root privileges to users and log root activity.

The basic philosophy is to give as few privileges as possible but still allow system users to complete their work.

By enabling the fs.protected_hardlinks kernel parameter, users can no longer create soft or hard links to files they do not own.

Disallowing such hardlinks mitigates vulnerabilities based on unsecure file systems accessed by privileged programs, avoiding an exploitation vector exploiting unsafe use of open() or creat().

Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised information system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider threats and the advanced persistent threat.

Satisfies: SRG-OS-000327-GPOS-00127, SRG-OS-000326-GPOS-00126

By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute-force attacks, is reduced. Limits are imposed by locking the account.

By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute-force attacks, is reduced. Limits are imposed by locking the account.

If the pam_faillock.so module is not loaded, the system will not correctly lockout accounts to prevent password guessing attacks.

Without auditing of these events, it may be harder or impossible to identify what an attacker did after an attack.

Satisfies: SRG-OS-000021-GPOS-00005, SRG-OS-000470-GPOS-00214

By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute-forcing, is reduced. Limits are imposed by locking the account.

Having account locks persist across reboots ensures that a locked account is only unlocked by an administrator.

If the locks did not persist across reboots, an attacker could reboot the system to continue brute force attacks against the accounts on the system.

The default /var/run/faillock directory is cleared upon reboot and should not be used.

Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance.

System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist.

The banner must be formatted in accordance with applicable DOD policy. Use the following verbiage for operating systems that can accommodate banners of 1300 characters:

"You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

Use the following verbiage for operating systems that have severe limitations on the number of characters that can be displayed in the banner:

"I've read & consent to terms in IS user agreem't."

If a login banner is not displayed, it may be difficult to prosecute an attacker.

Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088

Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance.

System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist.

The banner must be formatted in accordance with applicable DOD policy. Use the following verbiage for operating systems that can accommodate banners of 1300 characters:

"You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

Use the following verbiage for operating systems that have severe limitations on the number of characters that can be displayed in the banner:

"I've read & consent to terms in IS user agreem't."

If a login banner is not displayed, it may be difficult to prosecute an attacker.

Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088

The "s-nail" package provides the mail command required to allow sending email notifications of unauthorized configuration changes to designated personnel.

Kerberos authentication for SSH is often implemented using Generic Security Service Application Program Interface (GSSAPI). If Kerberos is enabled through SSH, the SSH daemon provides a means of access to the system's Kerberos implementation. Vulnerabilities in the system's Kerberos implementations may be subject to exploitation.

Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor.

Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization.

Verifying the authenticity of the software prior to installation validates the integrity of the patch or upgrade received from a vendor. This ensures the software has not been tampered with and that it has been provided by a trusted vendor. Self-signed certificates are not allowed by this requirement. The operating system should not have to verify the software again. This requirement does not mandate DOD certificates for this purpose; however, the certificate used to verify the software must be from an approved certificate authority (CA).

Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor.

Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization.

Verifying the authenticity of the software prior to installation validates the integrity of the patch or upgrade received from a vendor. This ensures the software has not been tampered with and that it has been provided by a trusted vendor. Self-signed certificates are disallowed by this requirement. The operating system should not have to verify the software again. This requirement does not mandate DOD certificates for this purpose; however, the certificate used to verify the software must be from an approved certificate authority (CA).

Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor.

Disabling kexec_load prevents an unsigned kernel image (that could be a windows kernel or modified vulnerable kernel) from being loaded. Kexec can be used subvert the entire secureboot process and should be avoided at all costs especially since it can load unsigned kernel images.

If AlmaLinux OS 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process.

This requirement applies to AlmaLinux OS 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.

If AlmaLinux OS 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process.

This requirement applies to AlmaLinux OS 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.

If AlmaLinux OS 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process.

This requirement applies to AlmaLinux OS 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.

If AlmaLinux OS 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process.

This requirement applies to AlmaLinux OS 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.

A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers or system operators trying to debug problems.

Enabling core dumps on production systems is not recommended; however, there may be overriding operational requirements to enable advanced debugging. Permitting temporary enablement of core dumps during such situations must be reviewed through local needs and policy.

A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers or system operators trying to debug problems.

Enabling core dumps on production systems is not recommended; however, there may be overriding operational requirements to enable advanced debugging. Permitting temporary enablement of core dumps during such situations must be reviewed through local needs and policy.

A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems.

Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations; therefore, service configuration files must be owned by the correct group to prevent unauthorized changes.

Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations; therefore, service configuration files must have the correct access rights to prevent unauthorized changes.

A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot.

Unowned files and directories may be unintentionally inherited if a user is assigned the same user identifier "UID" as the UID of the unowned files.

The "/etc/group-" file is a backup file of "/etc/group", and as such, contains information regarding groups that are configured on the system. Protection of this file is important for system security.

The "/etc/group" file contains information regarding groups that are configured on the system. Protection of this file is important for system security.

The "/etc/group" file contains information regarding groups that are configured on the system. Protection of this file is important for system security.

The "/boot/grub2/grub.cfg" file stores sensitive system configuration. Protection of this file is critical for system security.

The "/etc/gshadow-" file is a backup of "/etc/gshadow", and as such, contains group password hashes. Protection of this file is critical for system security.

The "/etc/gshadow-" file is a backup of "/etc/gshadow", and as such, contains group password hashes. Protection of this file is critical for system security.

The "/etc/gshadow" file contains group password hashes. Protection of this file is critical for system security.

Unnecessary service packages must not be installed to decrease the attack surface of the system.

Graphical display managers have a long history of security vulnerabilities and must not be used, unless approved and documented.

If local interactive users are not assigned a valid home directory, there is no place for the storage and control of files they should own.

If the Group Identifier (GID) of a local interactive users home directory is not the same as the primary GID of the user, this would allow unauthorized access to the users files, and users that share the same group may not be able to access files that they legitimately should.

Ensuring that "/home" is mounted on its own partition enables the setting of more restrictive mount options, and also helps ensure that users cannot trivially fill partitions used for log or audit data storage.

The executable search path (typically the $PATH environment variable) contains a list of directories for the shell to search to find executables. If this path includes the current working directory (other than the users home directory), executables in these directories may be executed instead of system commands.

This variable is formatted as a colon-separated list of directories. If there is an empty entry, such as a leading or trailing colon or two consecutive colons, this is interpreted as the current working directory. If deviations from the default system search path for the local interactive user are required, they must be documented with the information system security officer (ISSO).

Failure to restrict system access to authenticated users negatively impacts operating system security.

If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.

The "/etc/passwd-" file is a backup file of "/etc/passwd", and as such, contains information about the users that are configured on the system. Protection of this file is critical for system security.

The "/etc/passwd-" file is a backup file of "/etc/passwd", and as such, contains information about the users that are configured on the system. Protection of this file is critical for system security.

The "/etc/passwd" file contains information about the users that are configured on the system. Protection of this file is critical for system security.

The "/etc/shadow-" file is a backup file of "/etc/shadow", and as such, contains the list of local system accounts and password hashes. Protection of this file is critical for system security.

The "/etc/shadow-" file is a backup file of "/etc/shadow", and as such, contains the list of local system accounts and password hashes. Protection of this file is critical for system security.

The "/etc/shadow" file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security.

Failure to give ownership of this file to root provides the designated owner with access to sensitive information, which could weaken the system security posture.

If the "sudoers" file is not configured correctly, any user defined on the system can initiate privileged actions on the target system.

Setting the most restrictive default permissions ensures that when new accounts are created they do not have unnecessary access.

With a UMASK of 077, files will be created with 0600 permissions (owner read/write only) and directories will have 0700 permissions (owner read/write/execute only).

Setting the most restrictive default permissions ensures that when new accounts are created they do not have unnecessary access.

With a UMASK of 077, files will be created with 0600 permissions (owner read/write only) and directories will have 0700 permissions (owner read/write/execute only).

Accounts providing no operational purpose provide additional opportunities for system compromise. Unnecessary accounts include user accounts for individuals not requiring access to the system and application accounts for applications not installed on the system.

File integrity tools use cryptographic hashes for verifying file contents and directories have not been altered. These hashes must be FIPS 140-3 approved cryptographic hashes.

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack.

This feature of the IP protocol has few legitimate uses. It should be disabled unless absolutely required.

Failure to restrict network connectivity only to authorized systems permits inbound connections from malicious systems. It also permits outbound connections that may facilitate exfiltration of DOD data.

AlmaLinux OS 9 incorporates the "firewalld" daemon, which allows for many different configurations. One of these configurations is zones. Zones can be used to a deny-all, allow-by-exception approach. The default "drop" zone will drop all incoming network packets unless it is explicitly allowed by the configuration file or is related to an outgoing network connection.

Responding to broadcast (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks.

Ignoring ICMP echo requests (pings) sent to broadcast or multicast addresses makes the system slightly more difficult to enumerate on the network.

IP tunneling mechanisms can be used to bypass network filtering. If tunneling is required, it must be documented with the information system security officer (ISSO).

If unrestricted mail relaying is permitted, unauthorized senders could use this host as a mail relay for the purpose of sending spam or other unauthorized activity.

Network interfaces in promiscuous mode allow for the capture of all network traffic visible to the system. If unauthorized individuals can access these applications, it may allow them to collect information such as logon IDs, passwords, and key exchanges between systems.

If the system is being used to perform a network troubleshooting function, the use of these tools must be documented with the information system security officer (ISSO) and restricted to only authorized personnel.

ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table possibly revealing portions of the network topology.

The ability to send ICMP redirects is only appropriate for systems acting as routers.

The shosts.equiv files are used to configure host-based authentication for the system via SSH. Host-based authentication is not sufficient for preventing unauthorized access to the system, as it does not require interactive identification and authentication of a connection request, or for the use of two-factor authentication.

If compression is allowed in an SSH connection prior to authentication, vulnerabilities in the compression software could result in compromise of the system from an unauthenticated connection, potentially with root privileges.

Service configuration files enable or disable features of their respective services, which, if configured incorrectly, can lead to insecure and vulnerable configurations. Therefore, service configuration files must be owned by the correct group to prevent unauthorized changes.

SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.

If a public host key file is modified by an unauthorized user, the SSH service may be compromised.

Whilst public keys are publicly readable, they should not be writeable by nonowners.

Providing users feedback on when account accesses last occurred facilitates user recognition and reporting of unauthorized account use.

When X11 forwarding is enabled, there may be additional exposure to the server and client displays if the sshd proxy display is configured to listen on the wildcard address. By default, sshd binds the forwarding server to the loopback address and sets the hostname part of the DISPLAY environment variable to localhost. This prevents remote hosts from connecting to the proxy display.

Restricting TFTP to a specific directory prevents remote users from copying, transferring, or overwriting system files. Using the "-s" option causes the TFTP service to only serve files from the given directory.

Unlike text-based keyfiles, the binary database is impossible to check through most automated and all manual means; therefore, to evaluate dconf configuration, both have to be true at the same time—configuration files have to be compliant, and the database needs to be more recent than those keyfiles, which gives confidence that it reflects them.

Local initialization files are used to configure the user's shell environment upon logon. Malicious modification of these files could compromise accounts upon logon.

World-readable "dot files" such as .bash_history or .netrc can reveal plaintext credentials, such files should be further protected (e.g., 0600).

Kernel core dumps may contain the full contents of system memory at the time of the crash. Kernel core dumps consume a considerable amount of disk space and may result in denial of service by exhausting the available space on the target file system partition.

Unless the system is used for kernel development or testing, there is little need to run the kdump service.

A user who is at the console can reboot the system at the login screen. If restart or shutdown buttons are pressed at the login screen, this can create the risk of short-term loss of availability of systems due to reboot.

The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

User namespaces are used primarily for Linux containers. The value "0" disallows the use of user namespaces.

The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

To ensure that DNS resolver settings are respected, a DNS mode in Network Manager must be configured.

The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.

The hashes of important files like system executables should match the information given by the RPM database. Executables with erroneous hashes could be a sign of nefarious activity on the system.

Users need to be aware of activity that occurs regarding their account. Providing users with information regarding the number of unsuccessful attempts that were made to login to their account allows the user to determine if any unauthorized activity has occurred and gives them an opportunity to notify administrators.

The policycoreutils-python-utils package is required to operate and manage an SELinux environment and its policies. It provides utilities such as semanage, audit2allow, audit2why, chcat, and sandbox.

"rng-tools" provides hardware random number generator tools, such as those used in the formation of x509/PKI certificates.

Ensuring shells are not given to system accounts upon login makes it more difficult for attackers to make use of system accounts.

If user start-up files execute world-writable programs, especially in unprotected directories, they could be maliciously modified to destroy user files or otherwise compromise the system at the user level.

If the system is compromised at the user level, it is easier to elevate privileges to eventually compromise the system at the root and network level.

Ensuring that "/var" is mounted on its own partition enables the setting of more restrictive mount options. This helps protect system services such as daemons or other programs which use it. It is not uncommon for the "/var" directory to contain world-writable directories installed by other software packages.

System calls are special routines in the Linux kernel, which userspace applications ask to do privileged tasks. Invoking a system call is an expensive operation because the processor must interrupt the currently executing task and switch context to kernel mode, and then switch back to userspace after the system call completes. Virtual system calls map a page into userspace that contains some variables and the implementation of some system calls. This allows the system calls to be executed in userspace to alleviate the context switching expense.

Virtual system calls provide an opportunity of attack for a user who has control of the return instruction pointer. Disabling virtual system calls help to prevent return oriented programming (ROP) attacks via buffer overflows and overruns.

Unintentionally running a rsyslog server accepting remote messages puts the system at increased risk. Malicious rsyslog messages sent to the server could exploit vulnerabilities in the server software itself, could introduce misleading information into the system's logs, or could fill the system's storage leading to a denial of service.

If the system is intended to be a log aggregation server, its use must be documented with the information system security officer (ISSO).

The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.

The only legitimate location for device files is the "/dev" directory located on the root partition. The only exception to this is chroot jails.

The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.

The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files.

Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible.

Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.

The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files.

Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible.

Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.

The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible.

Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.

The organization must identify authorized software programs and permit execution of authorized software. The process used to identify software programs that are authorized to execute on organizational information systems is commonly referred to as allowlisting.

Utilizing an allowlist provides a configuration management method for allowing the execution of only authorized software. Using only authorized software decreases risk by limiting the number of potential vulnerabilities. Verification of allowlisted software occurs prior to execution or at system startup.

User home directories/folders may contain information of a sensitive nature. Nonprivileged users should coordinate any sharing of information with a system administrator (SA) through shared resources.

AlmaLinux OS 9 ships with many optional packages. One such package is a file access policy daemon called "fapolicyd". "fapolicyd" is a userspace daemon that determines access rights to files based on attributes of the process and file. It can be used to either blocklist or allowlist processes or file access.

Proceed with caution with enforcing the use of this daemon. Improper configuration may render the system nonfunctional. The "fapolicyd" API is not namespace aware and can cause issues when launching or running containers.

Not exposing the management interface of the chrony daemon on the network reduces the attack surface.

The iprutils package provides a suite of utilities to manage and configure SCSI devices supported by the ipr SCSI storage device driver.

The sendmail software was not developed with security in mind, and its design prevents it from being effectively contained by SELinux. Postfix must be used instead.

If TFTP is required for operational support (such as transmission of router configurations), its use must be documented with the information systems security manager (ISSM), restricted to only authorized personnel, and have access control rules established.

The gssproxy package is a proxy for GSS API credential handling and could expose secrets on some networks. It is not needed for normal function of the OS.

This requirement applies to wireless peripheral technologies (e.g., wireless mice, keyboards, displays, etc.) used with AlmaLinux OS 9 systems.

Wireless peripherals (e.g., Wi-Fi/Bluetooth/IR keyboards, mice and pointing devices, and near field communications [NFC]) present a unique challenge by creating an open, unsecured port on a computer. Wireless peripherals must meet DOD requirements for wireless data transmission and be approved for use by the authorizing official (AO). Even though some wireless peripherals, such as mice and pointing devices, do not ordinarily carry information that need to be protected, modification of communications with these wireless peripherals may be used to compromise the AlmaLinux OS 9 operating system.

Removing support for unneeded filesystem types reduces the local attack surface of the server.

Compressed ROM/RAM file system (or cramfs) is a read-only file system designed for simplicity and space-efficiency. It is mainly used in embedded and small-footprint systems.

Removing support for unneeded filesystem types reduces the local attack surface of the server.

A squashfs compressed filesystem image can be mounted without first decompressing the image.

Note that Snap packages use squashfs.

Removing support for unneeded filesystem types reduces the local attack surface of the server.

The UDF filesystem is used to write DVDs and so could assist in data exfiltration, the so-called "sneakernet".

Note that Microsoft Azure uses UDF.

"nfs-utils" provides a daemon for the kernel Network File System (NFS) server and related tools. This package also contains the "showmount" program. "showmount" queries the mount daemon on a remote host for information about the NFS server on the remote host. For example, "showmount" can display the clients that are mounted on that host.

The "rsh-server" service provides unencrypted remote access service, which does not provide for the confidentiality and integrity of user passwords or the remote session and has very weak authentication. If a privileged user were to login using this service, the privileged user password could be compromised.

The "rsh-server" package provides several obsolete and insecure network services. Removing it decreases the risk of accidental (or intentional) activation of those services.

Unnecessary service packages must not be installed to decrease the attack surface of the system. Graphical display managers have a long history of security vulnerabilities and must not be used, unless approved and documented.

The avahi package provides the zeroconf capability to discover remote services such as printers and announce itself as a service for sharing files and devices.

"Firewalld" provides an easy and effective way to block/limit remote access to the system via ports, services, and protocols.

Remote access services, such as those providing remote access to network devices and information systems, which lack automated control capabilities, increase risk and make remote user access management difficult at best.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

AlmaLinux OS 9 functionality (e.g., SSH) must be capable of taking enforcement action if the audit reveals unauthorized activity. Automated control of remote access sessions allows organizations to ensure ongoing compliance with remote access policies by enforcing connection rules of remote access applications on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets).

Satisfies: SRG-OS-000096-GPOS-00050, SRG-OS-000298-GPOS-00116, SRG-OS-000297-GPOS-00115

Without re-authentication, users may access resources or perform tasks for which they do not have authorization.

When operating systems provide the capability to escalate a functional capability, it is critical the user re-authenticate.

Without re-authentication, users may access resources or perform tasks for which they do not have authorization.

When operating systems provide the capability to escalate a functional capability, it is critical the user re-authenticate.

To ensure accountability and prevent unauthenticated access, organizational users must be identified and authenticated to prevent potential misuse and compromise of the system.

Organizational users include organizational employees or individuals the organization deems to have equivalent status of employees (e.g., contractors). Organizational users (and processes acting on behalf of users) must be uniquely identified and authenticated to all accesses, except for the following:

1) Accesses explicitly identified and documented by the organization. Organizations document specific user actions that can be performed on the information system without identification or authentication; and

2) Accesses that occur through authorized use of group authenticators without individual authentication. Organizations may require unique identification of individuals in group accounts (e.g., shared privilege accounts) or for detailed accountability of individual activity.

If a user is assigned the Group Identifier (GID) of a group that does not exist on the system, and a group with the GID is subsequently created, the user may have unintended rights to any files associated with the group.

Using an authentication device, such as a CAC or token that is separate from the information system, ensures that even if the information system is compromised, that compromise will not affect credentials stored on the authentication device.

Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification card and the DOD Common Access Card.

A privileged account is defined as an information system account with authorizations of a privileged user.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

This requirement only applies to components where this is specific to the function of the device or has the concept of an organizational user (e.g., VPN, proxy capability). This does not apply to authentication for the purpose of configuring the device itself (management).

This requires further clarification from NIST.

Using an authentication device, such as a CAC or token that is separate from the information system, ensures that even if the information system is compromised, that compromise will not affect credentials stored on the authentication device.

Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification card and the DOD Common Access Card.

A privileged account is defined as an information system account with authorizations of a privileged user.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

This requirement only applies to components where this is specific to the function of the device or has the concept of an organizational user (e.g., VPN, proxy capability). This does not apply to authentication for the purpose of configuring the device itself (management).

This requires further clarification from NIST.

Using an authentication device, such as a CAC or token that is separate from the information system, ensures that even if the information system is compromised, that compromise will not affect credentials stored on the authentication device.

Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification card and the DOD Common Access Card.

A privileged account is defined as an information system account with authorizations of a privileged user.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

This requirement only applies to components where this is specific to the function of the device or has the concept of an organizational user (e.g., VPN, proxy capability). This does not apply to authentication for the purpose of configuring the device itself (management).

This requires further clarification from NIST.

Satisfies: SRG-OS-000375-GPOS-00160, SRG-OS-000105-GPOS-00052, SRG-OS-000705-GPOS-00150

If an account has an empty password, anyone could log on and run commands with the privileges of that account.

Accounts with empty passwords should never be used in operational environments.

Satisfies: SRG-OS-000106-GPOS-00053, SRG-OS-000108-GPOS-00055

Even though the communications channel may be encrypted, an additional layer of security is gained by extending the policy of not logging directly on as root.

In addition, logging in with a user-specific account provides individual accountability of actions performed on the system.

The root account is a known default username, so should not allow direct login as half of the username/password combination is known, making it vulnerable to brute-force password guessing attacks.

Automatically mounting file systems permits easy introduction of unknown devices, thereby facilitating malicious activity.

Satisfies: SRG-OS-000378-GPOS-00163, SRG-OS-000114-GPOS-00059

The USBGuard-daemon is the main component of the USBGuard software framework. It runs as a service in the background and enforces the USB device authorization policy for all USB devices. The policy is defined by a set of rules using a rule language described in the usbguard-rules.conf file. The policy and the authorization state of USB devices can be modified during runtime using the USBGuard tool.

The system administrator (SA) must work with the site information system security officer (ISSO) to determine a list of authorized peripherals and establish rules within the USBGuard software framework to allow only authorized devices.

The USBGuard-daemon is the main component of the USBGuard software framework. It runs as a service in the background and enforces the USB device authorization policy for all USB devices. The policy is defined by a set of rules using a rule language described in the usbguard-rules.conf file. The policy and the authorization state of USB devices can be modified during runtime using the USBGuard tool.

The system administrator (SA) must work with the site information system security officer (ISSO) to determine a list of authorized peripherals and establish rules within the USBGuard software framework to allow only authorized devices.

Inactive identifiers pose a risk to systems and applications because attackers may exploit an inactive identifier and potentially obtain undetected access to the system.

Automatically disabling inactive accounts ensures that accounts which may not have been responsibly removed are not available to threat actors who may have compromised their credentials.

Owners of inactive accounts will not notice if unauthorized access to their user account has been obtained.

Enabling PAM password complexity permits enforcement of strong passwords and consequently makes the system less prone to dictionary attacks.

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

The shorter the password, the lower the number of possible combinations that need to be tested before the password is compromised.

Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password length is one factor of several that helps to determine strength and how long it takes to crack a password. Use of more characters in a password helps to exponentially increase the time and/or resources required to compromise the password.

The shorter the password, the lower the number of possible combinations that need to be tested before the password is compromised.

Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password length is one factor of several that helps to determine strength and how long it takes to crack a password. Use of more characters in a password helps to exponentially increase the time and/or resources required to compromise the password.

AlmaLinux OS 9 uses the PAM pwquality module as a mechanism to enforce password complexity. Configurations are set in the "/etc/security/pwquality.conf" file or further *.conf files within the "/etc/security/pwquality.conf.d/" directory.

The "minlen" parameter acts as a score of complexity based on the credit components of the pwquality module. By setting the credit to a negative value, not only will those components be required, but they will not count toward the total score of minlen. This will result in minlen requiring a 15-character minimum.

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Passwords must be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised.

Using more hashing rounds makes password cracking attacks more difficult.

Passwords must be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised.

The system must use a strong hashing algorithm to store the password.

Passwords must be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised.

The system must use a strong hashing algorithm to store the password.

Passwords must be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised.

A telnet server provides an unencrypted remote access mechanism that does not protect the confidentiality of user credentials or the remote session.

If a privileged user were to log on using this service, the privileged user password could be compromised. SSH or other encrypted session methods must be used instead.

Removing the server and client packages prevents inbound and outbound communications from being compromised.

Any password, no matter how complex, can eventually be cracked. Therefore, passwords must be changed periodically. If the operating system does not limit the lifetime of passwords and force users to change their passwords, there is the risk that the operating system passwords could be compromised.

Enforcing a minimum password lifetime helps to prevent repeated password changes to defeat the password reuse or history enforcement requirement. If users are allowed to immediately and continually change their password, then the password could be repeatedly changed in a short period of time to defeat the organization's policy regarding password reuse.

If the private key is discovered, an attacker can use the key to authenticate as an authorized user and gain access to the network infrastructure.

The cornerstone of the PKI is the private key used to encrypt or digitally sign information.

If the private key is stolen, this will lead to the compromise of the authentication and nonrepudiation gained through PKI because the attacker can use the private key to digitally sign documents and pretend to be the authorized user.

Both the holders of a digital certificate and the issuing authority must protect the computers, storage devices, or whatever they use to keep the private keys.

Without path validation, an informed trust decision by the relying party cannot be made when presented with any certificate not already explicitly trusted.

A trust anchor is an authoritative entity represented via a public key and associated data. It is used in the context of public key infrastructures, X.509 digital certificates, and DNSSEC.

When there is a chain of trust, usually the top entity to be trusted becomes the trust anchor; it can be, for example, a Certification Authority (CA). A certification path starts with the subject certificate and proceeds through a number of intermediate certificates up to a trusted root certificate, typically issued by a trusted CA.

This requirement verifies that a certification path to an accepted trust anchor is used for certificate validation and that the path includes status information. Path validation is necessary for a relying party to make an informed trust decision when presented with any certificate not already explicitly trusted. Status information for certification paths includes certificate revocation lists or online certificate status protocol responses. Validation of the certificate status information is out of scope for this requirement.

Satisfies: SRG-OS-000384-GPOS-00167, SRG-OS-000066-GPOS-00034, SRG-OS-000775-GPOS-00230, SRG-OS-000780-GPOS-00240

Providing the ability for remote users or systems to initiate a secure VPN connection protects information when it is transmitted over a wide area network.

Centralized cryptographic policies simplify applying secure ciphers across an operating system and the applications that run on that operating system. Use of weak or untested encryption algorithms undermines the purposes of using encryption to protect data.

Satisfies: SRG-OS-000394-GPOS-00174, SRG-OS-000393-GPOS-00173

Terminating an unresponsive SSH session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle SSH session will also free up resources committed by the managed network element.

Terminating network connections associated with communications sessions includes, for example, deallocating associated TCP/IP address/port pairs at the operating system level and deallocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean the operating system terminates all sessions or network access; it only ends the unresponsive session and releases the resources associated with that session.

Satisfies: SRG-OS-000395-GPOS-00175, SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109

Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session will also free up resources committed by the managed network element.

Terminating network connections associated with communications sessions includes, for example, de-allocating associated TCP/IP address/port pairs at the operating system level, and de-allocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean that the operating system terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session.

Exposing kernel pointers (through procfs or "seq_printf()") exposes kernel writeable structures, which may contain functions pointers. If a write vulnerability occurs in the kernel, allowing write access to any of this structure, the kernel can be compromised.

This option disallows any program without the CAP_SYSLOG capability to get the addresses of kernel pointers by replacing them with "0".

Restricting access to the kernel message buffer limits access to only root. This prevents attackers from gaining additional system information as a nonprivileged user.

Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000138-GPOS-00069

Untrusted Certificate Authorities (CA) can issue certificates, but they may be issued by organizations or individuals that seek to compromise DOD systems or by organizations with insufficient security controls. If the CA used for verifying the certificate is not a DOD-approved CA, trust of this CA has not been established.

The DOD will only accept PKI-certificates obtained from a DOD-approved internal or external certificate authority. Reliance on CAs for the establishment of secure sessions includes, for example, the use of SSL/TLS certificates.

AlmaLinux OS 9 systems handling data requiring "data at rest" protections must employ cryptographic mechanisms to prevent unauthorized disclosure and modification of the information at rest.

Selection of a cryptographic mechanism is based on the need to protect the integrity of organizational information. The strength of the mechanism is commensurate with the security category and/or classification of the information. Organizations have the flexibility to either encrypt all information on storage devices (i.e., full disk encryption) or encrypt specific data structures (e.g., files, records, or fields).

Satisfies: SRG-OS-000405-GPOS-00184, SRG-OS-000404-GPOS-00183, SRG-OS-000185-GPOS-00079

Policycoreutils contains the policy core utilities that are required for basic operation of an SELinux-enabled system.

These utilities include load_policy to load SELinux policies, setfile to label filesystems, newrole to switch roles, and run_init to run /etc/init.d scripts in the proper context.

Preventing unauthorized information transfers mitigates the risk of information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection.

This requirement generally applies to the design of an information technology product, but it can also apply to the configuration of particular information system components that are, or use, such products. This can be verified by acceptance/validation processes in DOD or other government agencies.

There may be shared resources with configurable protections (e.g., files in storage) that may be assessed on specific information system components.

Denial of Service (DoS) is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity.

This requirement addresses the configuration of the operating system to mitigate the impact of DoS attacks that have occurred or are ongoing on system availability. For each system, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exist to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or establishing memory partitions). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks.

Satisfies: SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00071

Without protection of the transmitted information, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read or altered.

This requirement applies to both internal and external networks and all types of information system components from which information can be transmitted (e.g., servers, mobile devices, notebook computers, printers, copiers, scanners, and facsimile machines). Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification.

Protecting the confidentiality and integrity of organizational information can be accomplished by physical means (e.g., employing physical distribution systems) or by logical means (e.g., employing cryptographic techniques). If physical means of protection are employed, then logical means (cryptography) do not have to be employed, and vice versa.

Satisfies: SRG-OS-000424-GPOS-00188, SRG-OS-000426-GPOS-00190

SSH environment options potentially allow users to bypass access restriction in some configurations.

This requirement applies to wireless peripheral technologies (e.g., wireless mice, keyboards, displays, etc.) used with AlmaLinux OS 9 systems.

Wireless peripherals (e.g., Wi-Fi/Bluetooth/IR keyboards, mice and pointing devices, and near field communications [NFC]) present a unique challenge by creating an open, unsecured port on a computer.

Wireless peripherals must meet DOD requirements for wireless data transmission and be approved for use by the authorizing official (AO). Even though some wireless peripherals, such as mice and pointing devices, do not ordinarily carry information that need to be protected, modification of communications with these wireless peripherals may be used to compromise the AlmaLinux OS 9 operating system.

Satisfies: SRG-OS-000481-GPOS-00481, SRG-OS-000299-GPOS-00117, SRG-OS-000300-GPOS-00118

Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the AlmaLinux OS 9 system or platform.

Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives.

The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.

Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the AlmaLinux OS 9 system or platform.

Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives.

The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.

Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the AlmaLinux OS 9 system or platform.

Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives.

The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.

ExecShield uses the segmentation feature on all x86 systems to prevent execution in memory higher than a certain address. It writes an address as a limit in the code segment descriptor, to control where code can be executed, on a per-process basis.

When the kernel places the memory regions of a process, such as the stack and heap, higher than this address, the hardware prevents execution in that address range.

Some adversaries launch attacks with the intent of executing code in nonexecutable regions of memory or in memory locations that are prohibited. Security safeguards employed to protect memory include, for example, data execution prevention and address space layout randomization. Data execution prevention safeguards can be either hardware-enforced or software-enforced with hardware providing the greater strength of mechanism.

Poisoning writes an arbitrary value to freed pages, so any modification or reference to that page after being freed or before being initialized will be detected and prevented. This prevents many types of use-after-free vulnerabilities at little performance cost. Also prevents leak of data and detection of corrupted memory.

init_on_free is a Linux kernel boot parameter that enhances security by initializing memory regions when they are freed, preventing data leakage. This process ensures that stale data in freed memory cannot be accessed by malicious programs.

SLUB canaries add a randomized value (canary) at the end of SLUB-allocated objects to detect memory corruption caused by buffer overflows or underflows. Redzoning adds padding (red zones) around SLUB-allocated objects to detect overflows or underflows by triggering a fault when adjacent memory is accessed. SLUB canaries are often more efficient and provide stronger detection against buffer overflows compared to redzoning. SLUB canaries are supported in hardened Linux kernels like the ones provided by Linux-hardened.

SLAB objects are blocks of physically contiguous memory. SLUB is the unqueued SLAB allocator.

Satisfies: SRG-OS-000433-GPOS-00192, SRG-OS-000134-GPOS-00068

Previous versions of software components that are not removed from the information system after updates have been installed may be exploited by some adversaries.

Setting the SELinux policy to "targeted" or a more specialized policy ensures the system will confine processes that are likely to be targeted for exploitation, such as network or system services.

Note: During the development or debugging of SELinux modules, it is common to temporarily place nonproduction systems in "permissive" mode. In such temporary cases, SELinux policies should be developed, and once work is completed, the system should be reconfigured to "targeted".

Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to the operating system. Changes to operating system configurations can have unintended side effects, some of which may be relevant to security.

Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's information management officer (IMO)/information system security officer (ISSO) and system administrators (SAs) must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item.

Notifications provided by information systems include messages to local computer consoles, and/or hardware indications, such as lights.

This capability must take into account operational requirements for availability for selecting an appropriate response. The organization may choose to shut down or restart the information system upon security function anomaly detection.

Satisfies: SRG-OS-000447-GPOS-00201, SRG-OS-000446-GPOS-00200, SRG-OS-000363-GPOS-00150

Without the capability to restrict which roles and individuals can select which events are audited, unauthorized personnel may be able to prevent the auditing of critical events. Misconfigured audits may degrade the system's performance by overwhelming the audit log. Misconfigured audits may also make it more difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000477-GPOS-00222, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000477-GPOS-00222, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000392-GPOS-00172, SRG-OS-000470-GPOS-00214, SRG-OS-000473-GPOS-00218

Without establishing what type of events occurred, the source of events, where events occurred, and the outcome of events, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack.

Audit record content that may be necessary to satisfy this requirement includes, for example, time stamps, source and destination addresses, user/process identifiers, event descriptions, success/fail indications, filenames involved, and access control or flow control rules invoked.

Associating event types with detected events in audit logs provides a means of investigating an attack, recognizing resource usage or capacity thresholds, or identifying an improperly configured AlmaLinux OS 9 system.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000038-GPOS-00016, SRG-OS-000039-GPOS-00017, SRG-OS-000040-GPOS-00018, SRG-OS-000041-GPOS-00019, SRG-OS-000042-GPOS-00020, SRG-OS-000042-GPOS-00021, SRG-OS-000051-GPOS-00024, SRG-OS-000392-GPOS-00172, SRG-OS-000473-GPOS-00218, SRG-OS-000472-GPOS-00217, SRG-OS-000474-GPOS-00219, SRG-OS-000365-GPOS-00152, SRG-OS-000358-GPOS-00145, SRG-OS-000348-GPOS-00136, SRG-OS-000349-GPOS-00137, SRG-OS-000350-GPOS-00138, SRG-OS-000351-GPOS-00139, SRG-OS-000352-GPOS-00140, SRG-OS-000353-GPOS-00141, SRG-OS-000354-GPOS-00142, SRG-OS-000337-GPOS-00129, SRG-OS-000062-GPOS-00031, SRG-OS-000054-GPOS-00025

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000064-GPOS-00033, SRG-OS-000458-GPOS-00203, SRG-OS-000461-GPOS-00205

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000468-GPOS-00212, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000064-GPOS-00033, SRG-OS-000466-GPOS-00210, SRG-OS-000458-GPOS-00203

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000466-GPOS-00210, SRG-OS-000467-GPOS-00211, SRG-OS-000468-GPOS-00212

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000064-GPOS-00033, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000466-GPOS-00210

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way.

The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000458-GPOS-00203, SRG-OS-000462-GPOS-00206, SRG-OS-000463-GPOS-00207, SRG-OS-000471-GPOS-00215, SRG-OS-000474-GPOS-00219, SRG-OS-000466-GPOS-00210, SRG-OS-000064-GPOS-00033

Placing "/var/log/audit" in its own partition enables better separation between audit files and other system files, and helps ensure that auditing cannot be halted due to the partition running out of space.

"audispd-plugins" provides plugins for the real-time interface to the audit subsystem, "audispd". These plugins can do things like relay events to remote machines or analyze events for suspicious behavior.

The audit system should have an action setup in the event the internal event queue becomes full so that no data is lost.

Information stored in one location is vulnerable to accidental or incidental deletion or alteration.

Off-loading is a common process in information systems with limited audit storage capacity.

Information stored in one location is vulnerable to accidental or incidental deletion or alteration.

Off-loading is a common process in information systems with limited audit storage capacity.

Information stored in one location is vulnerable to accidental or incidental deletion or alteration.

Off-loading is a common process in information systems with limited audit storage capacity.

If security personnel are not notified immediately when storage volume reaches 75 percent usage, they are unable to plan for audit record storage capacity expansion.

If security personnel are not notified immediately when storage volume reaches 75 percent usage, they are unable to plan for audit record storage capacity expansion.

It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability, and system operation may be adversely affected.

Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded.

This requirement applies to each audit data storage repository (i.e., distinct information system component where audit records are stored), the centralized audit storage capacity of organizations (i.e., all audit data storage repositories combined), or both.

It is critical that when the operating system is at risk of failing to process audit logs as required, it takes action to mitigate the failure. Audit processing failures include software/hardware errors; failures in the audit capturing mechanisms; and audit storage capacity being reached or exceeded. Responses to audit failure depend upon the nature of the failure mode.

When availability is an overriding concern, other approved actions in response to an audit failure are as follows:

1) If the failure was caused by the lack of audit record storage capacity, the operating system must continue generating audit records if possible (automatically restarting the audit service if necessary), overwriting the oldest audit records in a first-in-first-out manner.

2) If audit records are sent to a centralized collection server and communication with this server is lost or the server fails, the operating system must queue audit records locally until communication is restored or until the audit records are retrieved manually. Upon restoration of the connection to the centralized collection server, action should be taken to synchronize the local audit data with the collection server.

It is critical that when the operating system is at risk of failing to process audit logs as required, it takes action to mitigate the failure. Audit processing failures include software/hardware errors; failures in the audit capturing mechanisms; and audit storage capacity being reached or exceeded. Responses to audit failure depend upon the nature of the failure mode.

When availability is an overriding concern, other approved actions in response to an audit failure are as follows:

1) If the failure was caused by the lack of audit record storage capacity, the operating system must continue generating audit records if possible (automatically restarting the audit service if necessary), overwriting the oldest audit records in a first-in-first-out manner.

2) If audit records are sent to a centralized collection server and communication with this server is lost or the server fails, the operating system must queue audit records locally until communication is restored or until the audit records are retrieved manually. Upon restoration of the connection to the centralized collection server, action should be taken to synchronize the local audit data with the collection server.

It is critical that when the operating system is at risk of failing to process audit logs as required, it takes action to mitigate the failure. Audit processing failures include software/hardware errors; failures in the audit capturing mechanisms; and audit storage capacity being reached or exceeded. Responses to audit failure depend upon the nature of the failure mode.

When availability is an overriding concern, other approved actions in response to an audit failure are as follows:

1) If the failure was caused by the lack of audit record storage capacity, the operating system must continue generating audit records if possible (automatically restarting the audit service if necessary), overwriting the oldest audit records in a first-in-first-out manner.

2) If audit records are sent to a centralized collection server and communication with this server is lost or the server fails, the operating system must queue audit records locally until communication is restored or until the audit records are retrieved manually. Upon restoration of the connection to the centralized collection server, action should be taken to synchronize the local audit data with the collection server.

If option "freq" is not set to a value that requires audit records being written to disk after a threshold number is reached, then audit records may be lost.

Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate.

Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network.

Organizations should consider endpoints that may not have regular access to the authoritative time server (e.g., mobile, teleworking, and tactical endpoints).

Satisfies: SRG-OS-000355-GPOS-00143, SRG-OS-000359-GPOS-00146

Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events.

Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network. Organizations should consider setting time periods for different types of systems (e.g., financial, legal, or mission-critical systems).

Organizations should also consider endpoints that may not have regular access to the authoritative time server (e.g., mobile, teleworking, and tactical endpoints). This requirement is related to the comparison done every 24 hours in SRG-OS-000355 because a comparison must be done to determine the time difference.

Satisfies: SRG-OS-000356-GPOS-00144, SRG-OS-000359-GPOS-00146, SRG-OS-000785-GPOS-00250

Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality.

Audit information includes all information (e.g., audit records, audit settings, audit reports) needed to successfully audit operating system activity.

Satisfies: SRG-OS-000057-GPOS-00027, SRG-OS-000059-GPOS-00029

Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality.

Audit information includes all information (e.g., audit records, audit settings, audit reports) needed to successfully audit operating system activity.

Satisfies: SRG-OS-000057-GPOS-00027, SRG-OS-000059-GPOS-00029

Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information.

AlmaLinux OS 9 systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools, and the corresponding rights the user enjoys, to make access decisions regarding the access to audit tools.

Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.

Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information.

AlmaLinux OS 9 systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools, and the corresponding rights the user enjoys, to make access decisions regarding the access to audit tools.

Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.

Satisfies: SRG-OS-000256-GPOS-00097, SRG-OS-000258-GPOS-00099

Protecting the integrity of the tools used for auditing purposes is a critical step toward ensuring the integrity of audit information. Audit information includes all information (e.g., audit records, audit settings, and audit reports) needed to successfully audit information system activity.

Satisfies: SRG-OS-000278-GPOS-00108, SRG-OS-000257-GPOS-00098

Postfix is a free, open-source mail transfer agent (MTA) that sends and receives emails. It is a server-side application that can be used to set up a local mail server, create a null-client mail relay, use a Postfix server as a destination for multiple domains, or choose an LDAP directory instead of files for lookups. Postfix supports protocols like LDAP, SMTP AUTH (SASL), and TLS. It uses the Simple Mail Transfer Protocol (SMTP) to transfer emails between servers.

Satisfies: SRG-OS-000304-GPOS-00121, SRG-OS-000343-GPOS-00134, SRG-OS-000363-GPOS-00150, SRG-OS-000447-GPOS-00201