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RHEL-08-030200 - The RHEL 8 audit system must be configured to audit any usage of the setxattr, fsetxattr, lsetxattr, removexattr, fremovexattr, and lremovexattr system calls.

Information

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).

'Setxattr' is a system call used to set an extended attribute value.
'Fsetxattr' is a system call used to set an extended attribute value. This is used to set extended attributes on a file.
'Lsetxattr' is a system call used to set an extended attribute value. This is used to set extended attributes on a symbolic link.
'Removexattr' is a system call that removes extended attributes.
'Fremovexattr' is a system call that removes extended attributes. This is used for removal of extended attributes from a file.
'Lremovexattr' is a system call that removes extended attributes. This is used for removal of extended attributes from symbolic links.

When a user logs on, the AUID is set to the UID of the account that is 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 syscall made by all programs on the system. Therefore, it is very important to use syscall 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 syscalls into one rule whenever possible.

Satisfies: SRG-OS-000062-GPOS-00031, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000392-GPOS-00172, SRG-OS-000458-GPOS-00203, SRG-OS-000462-GPOS-00206, SRG-OS-000463-GPOS-00207, SRG-OS-000468-GPOS-00212, SRG-OS-000471-GPOS-00215, SRG-OS-000474-GPOS-00219, SRG-OS-000466-GPOS-00210

Solution

Configure RHEL 8 to audit the execution of the 'setxattr', 'fsetxattr', 'lsetxattr', 'removexattr', 'fremovexattr', and 'lremovexattr' system calls by adding or updating the following lines to '/etc/audit/rules.d/audit.rules':

-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=b64 -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=0 -k perm_mod

The audit daemon must be restarted for the changes to take effect.

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_RHEL_8_V2R1_STIG.zip

Item Details

Category: AUDIT AND ACCOUNTABILITY

References: 800-53|AU-12a., CAT|II, CCI|CCI-000169, Rule-ID|SV-230413r1017219_rule, STIG-ID|RHEL-08-030200, Vuln-ID|V-230413

Plugin: Unix

Control ID: cd964f7da6f4ee29d31ff7a2916c0c36bfd6bed97ae4e2b2405c918642eb4e65