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6.2.1.4 Ensure audit_backlog_limit is sufficient

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This audit has been deprecated and will be removed in a future update.

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Information

In the kernel-level audit subsystem, a socket buffer queue is used to hold audit events. Whenever a new audit event is received, it is logged and prepared to be added to this queue.

The kernel boot parameter audit_backlog_limit=N, with N representing the amount of messages, will ensure that a queue cannot grow beyond a certain size. If an audit event is logged which would grow the queue beyond this limit, then a failure occurs and is handled according to the system configuration

If an audit event is logged which would grow the queue beyond the audit_backlog_limit, then a failure occurs, auditd records will be lost, and potential malicious activity could go undetected.

Solution

Edit /etc/default/grub and add audit_backlog_limit=N to GRUB_CMDLINE_LINUX. The recommended size for N is 8192 or larger.

Example:

 GRUB_CMDLINE_LINUX="audit_backlog_limit=8192"

Run the following command to update the grub2 configuration:

 # update-grub

See Also

https://workbench.cisecurity.org/benchmarks/18959

Item Details

References: CSCv7|6.2, CSCv7|6.3

Plugin: Unix

Control ID: 894548e5481dc348318bff03d8589c1ba1cfb7e352a2efa0dceab177b13f7f4a