8.1.13 Collect Successful File System Mounts - '64bit mount'

Information

Monitor the use of the mount system call. The mount (and umount) system call controls the
mounting and unmounting of file systems. The parameters below configure the system to
create an audit record when the mount system call is used by a non-privileged user

*Rationale*

It is highly unusual for a non privileged user to mount file systems to the system. While
tracking mount commands gives the system administrator evidence that external media may
have been mounted (based on a review of the source of the mount and confirming it's an
external media type), it does not conclusively indicate that data was exported to the media.
System administrators who wish to determine if data were exported, would also have to
track successful open, creat and truncate system calls requiring write access to a file under
the mount point of the external media file system. This could give a fair indication that a
write occurred. The only way to truly prove it, would be to track successful writes to the
external media. Tracking write system calls could quickly fill up the audit log and is not
recommended. Recommendations on configuration options to track data export to media is
beyond the scope of this document.Note- This tracks successful and unsuccessful mount commands. File system mounts do not
have to come from external media and this action still does not verify write (e.g. CD ROMS)

Solution

For 64 bit systems, add the following lines to the /etc/audit/audit.rules file.

-a always,exit -F arch=b64 -S mount -F auid>=500 -F auid!=4294967295 -k mounts
-a always,exit -F arch=b32 -S mount -F auid>=500 -F auid!=4294967295 -k mounts

# Execute the following command to restart auditd
# pkill -HUP -P 1 auditd

For 32 bit systems, add the following lines to the /etc/audit/audit.rules file.

-a always,exit -F arch=b32 -S mount -F auid>=500 -F auid!=4294967295 -k mounts

# Execute the following command to restart auditd
# pkill -HUP -P 1 auditd

See Also

https://workbench.cisecurity.org/files/91

Item Details

Category: AUDIT AND ACCOUNTABILITY

References: 800-53|AU-12c.

Plugin: Unix

Control ID: 803ae5d132aa0b6724a3daff0aa04491d09495c9ef5649e4f697df387f593fea