Vulnerability Discussion

Information stored in one location is vulnerable to accidental or incidental deletion or alteration.

Offloading is a common process in information systems with limited audit storage capacity.

Satisfies: SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224

Check

Verify the audit event multiplexor is configured to offload audit records to a different system or storage media from the system being audited.

Check that audisp-remote plugin is installed:

$ dpkg -l | grep audispd-plugins
ii audispd-plugins 1:3.1.2-2.1build1.1 amd64 Plugins for the audit event dispatcher

If the packet is "not installed", this is a finding.

Check that the records are being offloaded to a remote server with the following command:

$ sudo grep -i active /etc/audit/plugins.d/au-remote.conf
active = yes

If "active" is not set to "yes", or the line is commented out, or is missing, this is a finding.

Check that audisp-remote plugin is configured to send audit logs to a different system:

$ sudo grep -i ^remote_server /etc/audit/audisp-remote.conf
remote_server = 192.168.122.126

If the "remote_server" parameter is not set, is set with a local address, or is set with an invalid address, this is a finding.

Fix

Configure the audit event multiplexor to offload audit records to a different system or storage media from the system being audited.

Install the audisp-remote plugin:

$ sudo apt install -y audispd-plugins

Set the audisp-remote plugin as active by editing the "/etc/audit/plugins.d/au-remote.conf" file:

$ sudo sed -i -E 's/active\s*=\s*no/active = yes/' /etc/audit/plugins.d/au-remote.conf

Set the address of the remote machine by editing the "/etc/audit/audisp-remote.conf" file:

$ sudo sed -i -E 's/(remote_server\s*=).*/\1 <remote addr>/' /etc/audit/audisp-remote.conf

where <remote addr> must be substituted by the address of the remote server receiving the audit log.

Make the audit service reload its configuration files:

$ sudo systemctl restart auditd.service