SV-238258r958446: The Ubuntu operating system must generate audit records for any use of the setxattr, fsetxattr, lsetxattr, removexattr, fremovexattr, and lremovexattr system calls. | Canonical Ubuntu 20.04 LTS STIG SCAP Benchmark

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Assessment Title

Rule Text

The Ubuntu operating system must generate audit records for any use of the setxattr, fsetxattr, lsetxattr, removexattr, fremovexattr, and lremovexattr system calls.

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). The system call rules are loaded into a matching engine that intercepts each syscall that all programs on the system makes. Therefore, it is very important to only use syscall rules when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance is helped, though, by combining syscalls into one rule whenever possible. Satisfies: SRG-OS-000064-GPOS-00033, SRG-OS-000462-GPOS-00206

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

IA Controls

NIST SP 800-53

Not mappedCCI-000172

References

DPMS Target Canonical Ubuntu 20.04 LTS DISA DPMS Target Canonical Ubuntu 20.04 LTS 5318

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.ubuntu2004:def:147
# The Ubuntu operating system must generate audit records for any use of the setxattr, fsetxattr, lsetxattr, removexattr, fremovexattr, and lremovexattr system calls.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Audit 32-bit invocations of setxattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\bsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of setxattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_2() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\bsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of setxattr by root
# textfilecontent54_object (textfilecontent54_test)
test_3() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\bsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of setxattr by root
# textfilecontent54_object (textfilecontent54_test)
test_4() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\bsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of lsetxattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_5() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\blsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of lsetxattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_6() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\blsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of lsetxattr by root
# textfilecontent54_object (textfilecontent54_test)
test_7() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\blsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of lsetxattr by root
# textfilecontent54_object (textfilecontent54_test)
test_8() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\blsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of fsetxattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_9() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\bfsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of fsetxattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_10() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\bfsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of fsetxattr by root
# textfilecontent54_object (textfilecontent54_test)
test_11() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\bfsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of fsetxattr by root
# textfilecontent54_object (textfilecontent54_test)
test_12() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\bfsetxattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of removexattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_13() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\bremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of removexattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_14() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\bremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of removexattr by root
# textfilecontent54_object (textfilecontent54_test)
test_15() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\bremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of removexattr by root
# textfilecontent54_object (textfilecontent54_test)
test_16() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\bremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of lremovexattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_17() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\blremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of lremovexattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_18() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\blremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of lremovexattr by root
# textfilecontent54_object (textfilecontent54_test)
test_19() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\blremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of lremovexattr by root
# textfilecontent54_object (textfilecontent54_test)
test_20() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\blremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of fremovexattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_21() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\bfremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of fremovexattr by interactive users
# textfilecontent54_object (textfilecontent54_test)
test_22() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\bfremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid>=1000\s+-F\s+auid!=(?:4294967295|-1|unset)(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 32-bit invocations of fremovexattr by root
# textfilecontent54_object (textfilecontent54_test)
test_23() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b32\s+(?:-S\s+\S+\s+)*-S\s+\S*\bfremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}
# Audit 64-bit invocations of fremovexattr by root
# textfilecontent54_object (textfilecontent54_test)
test_24() {
  grep -Pq '^\s*-a\s+(?:always,exit|exit,always)\s+-F\s+arch=b64\s+(?:-S\s+\S+\s+)*-S\s+\S*\bfremovexattr\b\S*\s+(?:-S\s+\S+\s+)*-F\s+auid=0(?:\s+(?:-k\s+|-F\s+key=)[-\w]+)*\s*$' '/etc/audit/audit.rules' &>/dev/null
}

if ( test_1 && test_2 && test_3 && test_4 && test_5 && test_6 && test_7 && test_8 && test_9 && test_10 && test_11 && test_12 && test_13 && test_14 && test_15 && test_16 && test_17 && test_18 && test_19 && test_20 && test_21 && test_22 && test_23 && test_24 ); 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 Definition: oval:mil.disa.stig.ubuntu2004:def:147
if [ ! -f "/etc/audit/rules.d/stig.rules" ]; then echo "PASS"; exit 0; fi
grep -q "^\\s*-a\\s+(?:always,exit|exit,always)\\s+-F\\s+arch=b32\\s+-S\\s+\\S*\\bsetxattr\\b\\S*\\s+-F\\s+auid>=1000\\s+-F\\s+auid != (?:4294967295|-1|unset)(?:\\s+-k\\s+perm_mod)*\\s*$" /etc/audit/rules.d/stig.rules || exit 1
grep -q "^\\s*-a\\s+(?:always,exit|exit,always)\\s+-F\\s+arch=b32\\s+-S\\s+\\S*\\bsetxattr\\b\\S*\\s+-F\\s+auid=0(?:\\s+-k\\s+perm_mod)*\\s*$" /etc/audit/rules.d/stig.rules || exit 1
grep -q "^\\s*-a\\s+(?:always,exit|exit,always)\\s+-F\\s+arch=b64\\s+-S\\s+\\S*\\bsetxattr\\b\\S*\\s+-F\\s+auid>=1000\\s+-F\\s+auid != (?:4294967295|-1|unset)(?:\\s+-k\\s+perm_mod)*\\s*$" /etc/audit/rules.d/stig.rules || exit 1
grep -q "^\\s*-a\\s+(?:always,exit|exit,always)\\s+-F\\s+arch=b64\\s+-S\\s+\\S*\\bsetxattr\\b\\S*\\s+-F\\s+auid=0(?:\\s+-k\\s+perm_mod)*\\s*$" /etc/audit/rules.d/stig.rules || exit 1
echo "PASS"; exit 0

Remediation

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "setxattr", "fsetxattr", "lsetxattr", "removexattr", "fremovexattr", and "lremovexattr" system calls. 
 
Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file: 
 
-a always,exit -F arch=b32 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid>=1000 -F auid!=4294967295 -k perm_mod 
-a always,exit -F arch=b32 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod  
-a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid>=1000 -F auid!=4294967295 -k perm_mod 
-a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod  
 
Note: For 32-bit architectures, only the 32-bit specific entries are required.
 
To reload the rules file, issue the following command: 
 
$ sudo augenrules --load