Successful/unsuccessful uses of the umount system call in TOSS 5 must generate an audit record.

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000477-GPOS-00222

Verify that TOSS 5 generates an audit record for all uses of the "umount" and system call with the following command:

$ sudo grep "umount" /etc/audit/audit.* 

-a always,exit -F arch=b32 -S umount -F auid>=1000 -F auid!=unset -k privileged-umount

If the command does not return a line or the line is commented out, this is a finding.

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "umount" system call by adding or updating the following rules in "/etc/audit/audit.rules" and adding the following rules to "/etc/audit/rules.d/perm_mod.rules" or updating the existing rules in files in the "/etc/audit/rules.d/" directory:

-a always,exit -F arch=b32 -S umount -F auid>=1000 -F auid!=unset -k privileged-umount

Restart the audit daemon for changes to take effect.