Vulnerability Discussion

In order to ensure Ubuntu operating systems have sufficient storage capacity in which to write the audit logs, Ubuntu operating system needs to be able to allocate audit record storage capacity.

The task of allocating audit record storage capacity is usually performed during initial installation of the Ubuntu operating system.

Check

Verify the Ubuntu operating system allocates audit record storage capacity to store at least one week's worth of audit records when audit records are not immediately sent to a central audit record storage facility.

Determine which partition the audit records are being written to with the following command:

# sudo grep log_file /etc/audit/auditd.conf
log_file = /var/log/audit/audit.log

Check the size of the partition that audit records are written to (with the example being /var/log/audit/) with the following command:

# df –h /var/log/audit/
/dev/sda2 24G 10.4G 13.6G 43% /var/log/audit

If the audit records are not written to a partition made specifically for audit records (/var/log/audit is a separate partition), determine the amount of space being used by other files in the partition with the following command:

#du –sh [audit_partition]
1.8G /var/log/audit

Note: The partition size needed to capture a week's worth of audit records is based on the activity level of the system and the total storage capacity available. In normal circumstances, 10.0 GB of storage space for audit records will be sufficient.

If the audit record partition is not allocated for sufficient storage capacity, this is a finding.

Fix

Allocate enough storage capacity for at least one week's worth of audit records when audit records are not immediately sent to a central audit record storage facility.

If audit records are stored on a partition made specifically for audit records, use the "parted" program to resize the partition with sufficient space to contain one week's worth of audit records.

If audit records are not stored on a partition made specifically for audit records, a new partition with sufficient amount of space will need be to be created.

Set the auditd server to point to the mount point where the audit records must be located:

# sudo sed -i -E 's@^(log_file\s*=\s*).*@\1 /audit.log@' /etc/audit/auditd.conf

where is the aforementioned mount point.