Vulnerability Discussion

Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to the operating system. Changes to operating system configurations can have unintended side effects, some of which may be relevant to security.

Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's IMO/ISSO and SAs must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item.

Check

Verify that Advanced Intrusion Detection Environment (AIDE) notifies the System Administrator
when anomalies in the operation of any security functions are discovered with the following command:

$ grep SILENTREPORTS /etc/default/aide

SILENTREPORTS=no

If SILENTREPORTS is commented out, this is a finding.

If SILENTREPORTS is set to "yes", this is a finding.

If SILENTREPORTS is not set to "no", this is a finding.

Fix

Configure the Ubuntu operating system to notify designated personnel if baseline configurations are changed in an unauthorized manner.

Modify the "SILENTREPORTS" parameter in the "/etc/default/aide" file with a value of "no" if it does not already exist.