linux_auditd_file_permissions_modification_via_chattr.yml

name: Linux Auditd File Permissions Modification Via Chattr
id: f2d1110d-b01c-4a58-9975-90a9edeb083a
version: 4
date: '2025-02-03'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects suspicious file permissions modifications using the chattr command, which may indicate an attacker attempting to manipulate file attributes to evade detection or prevent alteration. The chattr command can be used to make files immutable or restrict deletion, which can be leveraged to protect malicious files or disrupt system operations. By monitoring for unusual or unauthorized chattr usage, this analytic helps identify potential tampering with critical files, enabling security teams to quickly respond to and mitigate threats associated with unauthorized file attribute changes.
data_source:
- Linux Auditd Execve
search: '`linux_auditd` `linux_auditd_normalized_proctitle_process` | rename host as dest | rename comm as process_name | rename exe as process |  where LIKE(process_exec, "%chattr %") AND LIKE(process_exec, "% -i%") | stats count min(_time) as firstTime max(_time) as lastTime by process_exec proctitle normalized_proctitle_delimiter dest | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`| `linux_auditd_file_permissions_modification_via_chattr_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: Administrator or network operator can use this application for automation purposes. Please update the filter macros to remove false positives.
references:
- https://www.splunk.com/en_us/blog/security/deep-dive-on-persistence-privilege-escalation-technique-and-detection-in-linux-platform.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 ("$dest$") starthoursago=168  | 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: $info_min_time$
  latest_offset: $info_max_time$
rba:
  message: A [$process_exec$] event occurred on host - [$dest$] to modify file permissions
    using the "chattr" command.
  risk_objects:
  - field: dest
    type: system
    score: 30
  threat_objects: []
tags:
  analytic_story:
  - Linux Living Off The Land
  - Linux Privilege Escalation
  - Linux Persistence Techniques
  - Compromised Linux Host
  asset_type: Endpoint
  mitre_attack_id:
  - T1222.002
  - T1222
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1222.002/linux_auditd_chattr_i/linux_auditd_chattr_i.log
    source: /var/log/audit/audit.log
    sourcetype: linux:audit