Information
Reconstruction of harmful events or forensic analysis is not possible if audit records do not contain enough information.
At a minimum, the organization must audit the full-text recording of privileged commands. The organization must maintain audit trails in sufficient detail to reconstruct events to determine the cause and impact of compromise. The 'postdrop' command creates a file in the maildrop directory and copies its standard input to the file.
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.
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
Solution
Configure the audit system to generate an audit event for any use of the 'postdrop' command by adding or updating the following rule in the '/etc/audit/rules.d/audit.rules' file:
-a always,exit -F path=/usr/sbin/postdrop -F perm=x -F auid>=1000 -F auid!=unset -k privileged-unix-update
The audit daemon must be restarted for the changes to take effect. To restart the audit daemon, run the following command:
$ sudo service auditd restart
Item Details
Category: AUDIT AND ACCOUNTABILITY, MAINTENANCE
References: 800-53|AU-3, 800-53|AU-3(1), 800-53|AU-12a., 800-53|AU-12c., 800-53|MA-4(1)(a), CAT|II, CCI|CCI-000130, CCI|CCI-000135, CCI|CCI-000169, CCI|CCI-000172, CCI|CCI-002884, Rule-ID|SV-248762r958412_rule, STIG-ID|OL08-00-030311, Vuln-ID|V-248762
Control ID: 99457bd6f576972ed12e5c338f77c7721792f5c4554dffcce359b77842979b85