Details

The backlog limit has a default setting of 64

Rationale:

During boot if audit=1, then the backlog will hold 64 records. If more than 64 records are created during boot, auditd records will be lost and potential malicious activity could go undetected.

Solution

Edit /boot/grub/grub.conf or /boot/efi/EFI/*/grub.conf on UEFI systems and add audit_backlog_limit= to each line beginning with kernel:
Example:

[ -f /boot/efi/EFI/*/grub.conf ] && sed -ri ‘s/(^s*kernels+.*)$/1 audit_backlog_limit=8192/g’ /boot/efi/EFI/*/grub.conf || sed -ri ‘s/(^s*kernels+.*)$/1 audit_backlog_limit=8192/g’ /boot/grub/grub.conf

Supportive Information

The following resource is also helpful.

• https://workbench.cisecurity.org/files/3152https://workbench.cisecurity.org/files/3152

This security hardening control applies to the following category of controls within NIST 800-53: Audit and Accountability.This control applies to the following type of system Unix.

References

• 800-53|AU-3
• 800-53|AU-12
• CSCv7|6.2
• CSCv7|6.3

Source

• Tenable.com/audits