Kernel Driver Load

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Detects the loading of a Linux kernel module through system calls. Threat actors may leverage Linux kernel modules to load a rootkit on a system providing them with complete control and the ability to hide from security products. As other rules monitor for the addition of Linux kernel modules through system utilities or .ko files, this rule covers the gap that evasive rootkits leverage by monitoring for kernel module additions on the lowest level through auditd_manager.

Rule type: eql

Rule indices:

  • auditbeat-*
  • logs-auditd_manager.auditd-*

Severity: low

Risk score: 21

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

  • Data Source: Auditd Manager
  • Domain: Endpoint
  • OS: Linux
  • Use Case: Threat Detection
  • Tactic: Persistence
  • Tactic: Defense Evasion

Version: 4

Rule authors:

  • Elastic

Rule license: Elastic License v2

Setup

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Setup

This rule requires the use of the auditd_manager integration. Auditd_manager is a tool designed to simplify and enhance the management of the audit subsystem in Linux systems. It provides a user-friendly interface and automation capabilities for configuring and monitoring system auditing through the auditd daemon. With auditd_manager, administrators can easily define audit rules, track system events, and generate comprehensive audit reports, improving overall security and compliance in the system. The following steps should be executed in order to install and deploy auditd_manager on a Linux system.

Kibana -->
Management -->
Integrations -->
Auditd Manager -->
Add Auditd Manager

Auditd_manager subscribes to the kernel and receives events as they occur without any additional configuration. However, if more advanced configuration is required to detect specific behavior, audit rules can be added to the integration in either the "audit rules" configuration box or the "auditd rule files" box by specifying a file to read the audit rules from.

For this detection rule to trigger, the following additional audit rules are required to be added to the integration:

-a always,exit -F arch=b64 -S finit_module -S init_module -S delete_module -F auid!=-1 -k modules
-a always,exit -F arch=b32 -S finit_module -S init_module -S delete_module -F auid!=-1 -k modules

Add the newly installed auditd manager to an agent policy, and deploy the agent on a Linux system from which auditd log files are desirable.

Rule query

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driver where host.os.type == "linux" and event.action == "loaded-kernel-module" and
auditd.data.syscall in ("init_module", "finit_module")

Framework: MITRE ATT&CKTM