SV-215070r610931: The audit system must be configured to audit any usage of the fsetxattr system call. | Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide

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Assessment Title

Rule Text

The audit system must be configured to audit any usage of the fsetxattr system call.

Description

Discussion Text

Without generating audit records that are 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). 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

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000172Not mappedCCI-000169Not mappedCCI-000135Not mappedCCI-000130Not mappedCCI-002884V-75721SV-90401

References

DPMS Target Canonical Ubuntu 16.04 LTS DISA DPMS Target Canonical Ubuntu 16.04 LTS 4011

Checks

DISA STIG (Manual Reference)

Verify if the Ubuntu operating system is configured to audit the execution of the "fsetxattr" system call, by running the following command:

# sudo grep -w fsetxattr /etc/audit/audit.rules

-a always,exit -F arch=b32 -S fsetxattr -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S fsetxattr -F auid>=1000 -F auid!=4294967295 -k perm_mod

-a always,exit -F arch=b32 -S fsetxattr -F auid=0 -k perm_mod
-a always,exit -F arch=b64 -S fsetxattr -F auid=0 -k perm_mod

If the command does not return all lines, or the lines are commented out, this is a finding.

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.stig.ubuntu1604:def:198
# The audit system must be configured to audit any usage of the fsetxattr system call.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# package auditd is installed
# dpkginfo_object (dpkginfo_test)
test_1() {
  grep -A1 '^Package: auditd$' /var/lib/dpkg/status &>/dev/null
}
# check for auditd
# process58_object (process58_test)
test_2() {
  ps -eo args | grep -P '^\/sbin\/auditd\b' &>/dev/null
}
# Audit 32-bit invocations of fsetxattr syscall by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_3() {
  grep -Pq '^\s*-a\s+(always,exit|exit,always)\s+-F\s+arch=b32\s+(?:.*(-S[\s]+fsetxattr[\s]+|([\s]+|[,])fsetxattr([\s]+|[,])).*)-F\s+auid>=1000\s+-F\s+auid!=4294967295(\s+(-k\s+|-F\s+key=)\S+)?\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of fsetxattr syscall by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_4() {
  grep -Pq '^\s*-a\s+(always,exit|exit,always)\s+-F\s+arch=b64\s+(?:.*(-S[\s]+fsetxattr[\s]+|([\s]+|[,])fsetxattr([\s]+|[,])).*)-F\s+auid>=1000\s+-F\s+auid!=4294967295(\s+(-k\s+|-F\s+key=)\S+)?\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of fsetxattr syscall by root
# textfilecontent54_object (textfilecontent54_test)
test_5() {
  grep -Pq '^\s*-a\s+(always,exit|exit,always)\s+-F\s+arch=b32\s+(?:.*(-S[\s]+fsetxattr[\s]+|([\s]+|[,])fsetxattr([\s]+|[,])).*)-F\s+auid=0(\s+(-k\s+|-F\s+key=)\S+)?\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of fsetxattr syscall by root
# textfilecontent54_object (textfilecontent54_test)
test_6() {
  grep -Pq '^\s*-a\s+(always,exit|exit,always)\s+-F\s+arch=b64\s+(?:.*(-S[\s]+fsetxattr[\s]+|([\s]+|[,])fsetxattr([\s]+|[,])).*)-F\s+auid=0(\s+(-k\s+|-F\s+key=)\S+)?\s*$' '/etc/audit/audit.rules' &>/dev/null
}

if ( test_1 && test_2 && test_3 && test_4 && test_5 && test_6 ); then
  echo "PASS"
else
  echo "FAIL"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# oval:mil.disa.stig.ubuntu1604:def:198

if ! dpkg -s auditd &> /dev/null; then echo "FAIL"; exit 1; fi
if ! pgrep -f "^/sbin/auditd$" &> /dev/null; then echo "FAIL"; exit 1; fi

if ! grep -q "^\\s*-a\\s+(always,exit|exit,always)\\s+-F\\s+arch=b32\\s+-S\\s+fsetxattr\\s+-F\\s+auid>=1000\\s+-F\\s+auid != 4294967295\\s*$" /etc/audit/audit.rules; then echo "FAIL"; exit 1; fi
if ! grep -q "^\\s*-a\\s+(always,exit|exit,always)\\s+-F\\s+arch=b64\\s+-S\\s+fsetxattr\\s+-F\\s+auid>=1000\\s+-F\\s+auid != 4294967295\\s*$" /etc/audit/audit.rules; then echo "FAIL"; exit 1; fi
if ! grep -q "^\\s*-a\\s+(always,exit|exit,always)\\s+-F\\s+arch=b32\\s+-S\\s+fsetxattr\\s+-F\\s+auid=0\\s*$" /etc/audit/audit.rules; then echo "FAIL"; exit 1; fi
if ! grep -q "^\\s*-a\\s+(always,exit|exit,always)\\s+-F\\s+arch=b64\\s+-S\\s+fsetxattr\\s+-F\\s+auid=0\\s*$" /etc/audit/audit.rules; then echo "FAIL"; exit 1; fi

echo "PASS"; exit 0

Remediation

Configure the Ubuntu operating system to audit the execution of the "fsetxattr" system call, by adding the following lines to "/etc/audit/audit.rules":

-a always,exit -F arch=b32 -S fsetxattr -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S fsetxattr -F auid>=1000 -F auid!=4294967295 -k perm_mod

-a always,exit -F arch=b32 -S fsetxattr -F auid=0 -k perm_mod
-a always,exit -F arch=b64 -S fsetxattr -F auid=0 -k perm_mod

The audit daemon must be restarted for the changes to take effect. To restart the audit daemon, run the following command:

# sudo systemctl restart auditd.service