Detection rules › Splunk

Linux File Created In Kernel Driver Directory

Status
production
Severity
low
Group by
CreationUtcTime, computer_name, event_action, file_access_time, file_acl, file_hash, file_modify_time, file_name, file_size, process_guid, process_id, target_filename, user, vendor_product
Author
Teoderick Contreras, Splunk
Source
github.com/splunk/security_content

The following analytic detects the creation of files in the Linux kernel/driver directory. It leverages filesystem data to identify new files in this critical directory. This activity is significant because the kernel/driver directory is typically reserved for kernel modules, and unauthorized file creation here can indicate a rootkit installation. If confirmed malicious, this could allow an attacker to gain high-level privileges, potentially compromising the entire system by executing code at the kernel level.

MITRE ATT&CK coverage

Rule body splunk

name: Linux File Created In Kernel Driver Directory
id: b85bbeec-6326-11ec-9311-acde48001122
version: 11
creation_date: '2022-01-05'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects the creation of files in the Linux kernel/driver directory. It leverages filesystem data to identify new files in this critical directory. This activity is significant because the kernel/driver directory is typically reserved for kernel modules, and unauthorized file creation here can indicate a rootkit installation. If confirmed malicious, this could allow an attacker to gain high-level privileges, potentially compromising the entire system by executing code at the kernel level.
data_source:
    - Sysmon for Linux EventID 11
search: |-
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
      WHERE Filesystem.file_path IN ("*/kernel/drivers/*")
      BY Filesystem.action Filesystem.dest Filesystem.file_access_time
         Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time
         Filesystem.file_name Filesystem.file_path Filesystem.file_acl
         Filesystem.file_size Filesystem.process_guid Filesystem.process_id
         Filesystem.user Filesystem.vendor_product
    | `drop_dm_object_name(Filesystem)`
    | `security_content_ctime(lastTime)`
    | `security_content_ctime(firstTime)`
    | `linux_file_created_in_kernel_driver_directory_filter`
how_to_implement: To successfully implement this search, you need to be ingesting logs with the file name, file path, and process_guid executions from your endpoints. If you are using Sysmon, you can use the Add-on for Linux Sysmon from Splunkbase.
known_false_positives: Administrator or network operator can create file in this folders for automation purposes. Please update the filter macros to remove false positives.
references:
    - https://docs.fedoraproject.org/en-US/fedora/rawhide/system-administrators-guide/kernel-module-driver-configuration/Working_with_Kernel_Modules/
    - https://security.stackexchange.com/questions/175953/how-to-load-a-malicious-lkm-at-startup
    - https://0x00sec.org/t/kernel-rootkits-getting-your-hands-dirty/1485
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 file $file_name$ is created in $file_path$ on $dest$
analytic_story:
    - Linux Privilege Escalation
    - Linux Persistence Techniques
    - Linux Rootkit
asset_type: Endpoint
mitre_attack_id:
    - T1547.006
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/T1547.006/loading_linux_kernel_module/sysmon_linux.log
          source: Syslog:Linux-Sysmon/Operational
          sourcetype: sysmon:linux
      test_type: unit

Stages and Predicates

Stage 1: tstats

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
  WHERE Filesystem.file_path IN ("*/kernel/drivers/*")
  BY Filesystem.action Filesystem.dest Filesystem.file_access_time
     Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time
     Filesystem.file_name Filesystem.file_path Filesystem.file_acl
     Filesystem.file_size Filesystem.process_guid Filesystem.process_id
     Filesystem.user Filesystem.vendor_product

Stage 2: search

| `drop_dm_object_name(Filesystem)`

Stage 3: search

| `security_content_ctime(lastTime)`

Stage 4: search

| `security_content_ctime(firstTime)`

Stage 5: search

| `linux_file_created_in_kernel_driver_directory_filter`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Filesystem.file_pathin
  • "*/kernel/drivers/*"