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6.3.2 Ensure filesystem integrity is regularly checked

Information

Periodic checking of filesystem integrity detects unauthorized changes to files. AIDE (Advanced Intrusion Detection Environment) compares the current state of the filesystem against a previously initialized baseline database; this recommendation ensures that comparison runs automatically on a regular schedule rather than only on demand.

Periodic file checking allows the system administrator to determine on a regular basis if critical files have been changed in an unauthorized fashion. Running the integrity check on a defined schedule -- rather than manually or ad hoc -- ensures changes are detected consistently and reduces the window in which unauthorized modifications can go unnoticed.

Solution

Configure a systemd timer to run a periodic AIDE integrity check.

 - Create the file /etc/systemd/system/aidecheck.service with the following content:

[Unit]
Description=Aide Check

[Service]
Type=oneshot
ExecStart=/usr/sbin/aide --check

 - Create the file /etc/systemd/system/aidecheck.timer with the following content:

[Unit]
Description=Aide check every day at 5AM

[Timer]
OnCalendar=*-*-* 05:00:00
Persistent=true
Unit=aidecheck.service

[Install]
WantedBy=timers.target

 - Run the following commands to set access on the unit files, reload systemd, and enable the timer:

# chown root:root /etc/systemd/system/aidecheck.service /etc/systemd/system/aidecheck.timer
# chmod 0644 /etc/systemd/system/aidecheck.service /etc/systemd/system/aidecheck.timer
# systemctl daemon-reload
# systemctl enable --now aidecheck.timer

Impact:

Scheduled integrity checks consume CPU and I/O when they run; choose a schedule and time that balance timely detection against system load.

See Also

https://workbench.cisecurity.org/benchmarks/27893

Item Details

Category: ACCESS CONTROL, AUDIT AND ACCOUNTABILITY, SYSTEM AND INFORMATION INTEGRITY

References: 800-53|AC-6(9), 800-53|AU-2, 800-53|AU-12, 800-53|SI-7, CSCv7|14.9

Plugin: Unix

Control ID: 264062936c4dd50d900746f9e5b561a4d88d0fe20dd74343a0a7b90d8090e89d