Ubuntu 22.04 LTS must generate audit records for any use of the setxattr, fsetxattr, lsetxattr, removexattr, fremovexattr, and lremovexattr system calls.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-260638	UBTU-22-654180	SV-260638r958446_rule		Medium

Description
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). 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

Description

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). 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

STIG	Date
Canonical Ubuntu 22.04 LTS Security Technical Implementation Guide	2024-05-30

Details

Check Text ( C-64367r953725_chk )
Verify Ubuntu 22.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "setxattr", "fsetxattr", "lsetxattr", "removexattr", "fremovexattr", and "lremovexattr" system calls by using the following command: $ sudo auditctl -l \| grep xattr -a always,exit -F arch=b32 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid>=1000 -F auid!=-1 -F key=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!=-1 -F key=perm_mod -a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod If the command does not return audit rules for the "setxattr", "fsetxattr", "lsetxattr", "removexattr", "fremovexattr" and "lremovexattr" syscalls or the lines are commented out, this is a finding. Note: The "key=" value is arbitrary and can be different from the example output above.

Check Text ( C-64367r953725_chk )

Verify Ubuntu 22.04 LTS generates an audit record upon successful/unsuccessful attempts to use the "setxattr", "fsetxattr", "lsetxattr", "removexattr", "fremovexattr", and "lremovexattr" system calls by using the following command:

$ sudo auditctl -l | grep xattr
-a always,exit -F arch=b32 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid>=1000 -F auid!=-1 -F key=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!=-1 -F key=perm_mod
-a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod

If the command does not return audit rules for the "setxattr", "fsetxattr", "lsetxattr", "removexattr", "fremovexattr" and "lremovexattr" syscalls or the lines are commented out, this is a finding.

Note: The "key=" value is arbitrary and can be different from the example output above.

Fix Text (F-64275r953726_fix)
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 modify the following lines 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!=unset -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!=unset -k perm_mod -a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod To reload the rules file, issue the following command: $ sudo augenrules --load Note: The "-k " at the end of the line gives the rule a unique meaning to help during an audit investigation. The does not need to match the example above.

Fix Text (F-64275r953726_fix)

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 modify the following lines 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!=unset -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!=unset -k perm_mod
-a always,exit -F arch=b64 -S setxattr,fsetxattr,lsetxattr,removexattr,fremovexattr,lremovexattr -F auid=0 -k perm_mod

To reload the rules file, issue the following command:

$ sudo augenrules --load

Note: The "-k " at the end of the line gives the rule a unique meaning to help during an audit investigation. The does not need to match the example above.