Linux Auditd Kernel Module Enumeration

name: Linux Auditd Kernel Module Enumeration
id: d1b088de-c47a-4572-9339-bdcc26493b32
version: 10
creation_date: '2024-08-09'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic identifies the use of the 'kmod' process to list kernel modules on a Linux system. This detection leverages data from Linux Auditd, focusing on process names and command-line executions. While listing kernel modules is not inherently malicious, it can be a precursor to loading unauthorized modules using 'insmod'. If confirmed malicious, this activity could allow an attacker to load kernel modules, potentially leading to privilege escalation, persistence, or other malicious actions within the system.
data_source:
    - Linux Auditd Syscall
search: |-
    `linux_auditd` type=SYSCALL comm=lsmod
      | rename host as dest
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY comm exe syscall
           uid ppid pid
           success dest
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `linux_auditd_kernel_module_enumeration_filter`
how_to_implement: To implement this detection, the process begins by ingesting auditd data, that consists of SYSCALL, TYPE, EXECVE and PROCTITLE events, which captures command-line executions and process details on Unix/Linux systems. These logs should be ingested and processed using Splunk Add-on for Unix and Linux (https://splunkbase.splunk.com/app/833), which is essential for correctly parsing and categorizing the data. The next step involves normalizing the field names  to match the field names set by the Splunk Common Information Model (CIM) to ensure consistency across different data sources and enhance the efficiency of data modeling. This approach enables effective monitoring and detection of linux endpoints where auditd is deployed
known_false_positives: False positives are present based on automated tooling or system administrative usage. Filter as needed.
references:
    - https://man7.org/linux/man-pages/man8/kmod.8.html
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: A SYSCALL - [$comm$] event was executed on host - [$dest$] to list kernel modules.
analytic_story:
    - Compromised Linux Host
    - XorDDos
    - Linux Rootkit
asset_type: Endpoint
mitre_attack_id:
    - T1082
    - T1014
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1082/linux_auditd_lsmod_new/linux_auditd_new_lsmod.log
          source: auditd
          sourcetype: auditd
      test_type: unit