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CIS Ubuntu 14.04 LTS - 4.1.17 Ensure kernel module loading and unloading is collected

DevOps & Security
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Collect audit events for kernel module loading and unloading operations

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4.1.17 Ensure kernel module loading and unloading is collected (Scored)

Profile Applicability

  • Level 2 - Server
  • Level 2 - Workstation

Description

Monitor the loading and unloading of kernel modules. The programs insmod (install a kernel module), rmmod (remove a kernel module), and modprobe (a more sophisticated program to load and unload modules, as well as some other features) control loading and unloading of modules. The init_module (load a module) and delete_module (delete a module) system calls control loading and unloading of modules. Any execution of the loading and unloading module programs and system calls will trigger an audit record with an identifier of "modules".

Rationale

Monitoring the use of insmod, rmmod and modprobe could provide system administrators with evidence that an unauthorized user loaded or unloaded a kernel module, possibly compromising the security of the system. Monitoring of the init_module and delete_module system calls would reflect an unauthorized user attempting to use a different program to load and unload modules.

Audit Procedure

On a 32 bit system run the following commands:

grep modules /etc/audit/audit.rules
auditctl -l | grep modules

Verify output of both matches:

-w /sbin/insmod -p x -k modules
-w /sbin/rmmod -p x -k modules
-w /sbin/modprobe -p x -k modules
-a always,exit -F arch=b32 -S init_module -S delete_module -k modules

On a 64 bit system run the following commands:

grep modules /etc/audit/audit.rules
auditctl -l | grep modules

Verify output of both matches:

-w /sbin/insmod -p x -k modules
-w /sbin/rmmod -p x -k modules
-w /sbin/modprobe -p x -k modules
-a always,exit -F arch=b64 -S init_module -S delete_module -k modules

Expected Result

The audit rules for modules should be present and active.

Remediation

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

-w /sbin/insmod -p x -k modules
-w /sbin/rmmod -p x -k modules
-w /sbin/modprobe -p x -k modules
-a always,exit -F arch=b32 -S init_module -S delete_module -k modules

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

-w /sbin/insmod -p x -k modules
-w /sbin/rmmod -p x -k modules
-w /sbin/modprobe -p x -k modules
-a always,exit -F arch=b64 -S init_module -S delete_module -k modules

Notes: Reloading the auditd config to set active settings may require a system reboot.

Default Value

Not configured by default.

References

  1. CIS Controls v6.1 - 3 Secure Configurations for Hardware and Software on Mobile Devices, Laptops, Workstations, and Servers

Profile

  • Level 2 - Server
  • Level 2 - Workstation