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6.3.3.19 Ensure kernel module loading unloading and modification is collected

Warning! Audit Deprecated

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

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Information

Monitor the loading and unloading of kernel modules. All the loading / listing / dependency checking of modules is done by kmod via symbolic links.

The following system calls control loading and unloading of modules:

 - init_module - load a module
 - finit_module - load a module (used when the overhead of using cryptographically signed modules to determine the authenticity of a module can be avoided)
 - delete_module - delete a module
 - create_module - create a loadable module entry
 - query_module - query the kernel for various bits pertaining to modules

Any execution of the loading and unloading module programs and system calls will trigger an audit record with an identifier of modules.

Monitoring the use of all the various ways to manipulate kernel modules could provide system administrators with evidence that an unauthorized change was made to a kernel module, possibly compromising the security of the system.

Solution

Create audit rules

Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension, with the relevant rules to monitor kernel module modification.

Example:

#!/usr/bin/env bash

{
 UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
 [ -n "${UID_MIN}" ] && printf "
 -a always,exit -F arch=b64 -S init_module,finit_module,delete_module,create_module,query_module -F auid>=${UID_MIN} -F auid!=unset -k kernel_modules
 -a always,exit -F path=/usr/bin/kmod -F perm=x -F auid>=${UID_MIN} -F auid!=unset -k kernel_modules
 " >> /etc/audit/rules.d/50-kernel_modules.rules || printf "ERROR: Variable 'UID_MIN' is unset.\n"
}

Load audit rules

Merge and load the rules into active configuration:

# augenrules --load

Check if reboot is required.

# if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot required to load rules\n"; fi

See Also

https://workbench.cisecurity.org/benchmarks/18211

Item Details

References: CSCv7|6.2

Plugin: Unix

Control ID: fa6d0d6e02a53f89f3b4d8bfc1ade3e6fe96e09edd70bc444f00f9524365a498