Linux Auditd Doas Conf File Creation

name: Linux Auditd Doas Conf File Creation
id: 61059783-574b-40d2-ac2f-69b898afd6b4
version: 11
creation_date: '2024-08-09'
modification_date: '2026-05-13'
author: Teoderick Contreras, Nasreddine Bencherchali, Splunk
status: production
type: TTP
description: |
    The following analytic detects the creation of the doas.conf file on a Linux host.
    This file is used by the doas utility to allow standard users to perform tasks as root, similar to sudo.
    The detection leverages Linux Auditd data, focusing on the creation of the doas.conf file.
    This activity is significant because it can indicate an attempt to gain elevated privileges, potentially by an adversary. If confirmed malicious, this could allow an attacker to execute commands with root commands with root privileges, leading to full system compromise.
data_source:
    - Linux Auditd Path
    - Linux Auditd Cwd
search: |
    `linux_auditd`
    (
      (type=PATH nametype="CREATE")
      OR
      type=CWD
    )
    | rex "msg=audit\([^)]*:(?<audit_id>\d+)\)"
    
    | stats
      values(type) as types
      values(name) as names
      values(nametype) as nametype
      values(cwd) as cwd_list
      values(_time) as event_times
      by audit_id host
    
    | eval current_working_directory = coalesce(mvindex(cwd_list, 0), "N/A")
    | eval candidate_paths = mvmap(names, if(match(names, "^/"), names, current_working_directory + "/" + names))
    | eval matched_paths = mvfilter(match(candidate_paths, "/etc/doas.conf.*"))
    | eval match_count = mvcount(matched_paths)
    | eval reconstructed_path = mvindex(matched_paths, 0)
    | eval e_time = mvindex(event_times, 0)
    | where match_count > 0
    | rename host as dest
    
    | stats count min(e_time) as firstTime max(e_time) as lastTime
      values(nametype) as nametype
      by current_working_directory
         reconstructed_path
         match_count
         dest
         audit_id
    
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | table nametype current_working_directory reconstructed_path dest audit_id match_count firstTime lastTime
    | `linux_auditd_doas_conf_file_creation_filter`
how_to_implement: |
    To implement this detection, the process begins by ingesting auditd
    data, that consist 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 and make sure the type=CWD record type is activate in your auditd configuration.
    This approach enables effective monitoring and detection of linux endpoints where auditd is deployed.
known_false_positives: |
    Administrator or network operator can execute this command.
    Please update the filter macros to remove false positives.
references:
    - https://wiki.gentoo.org/wiki/Doas
    - https://www.makeuseof.com/how-to-install-and-use-doas/
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"
finding:
    title: A $reconstructed_path$ file was created on host - [$dest$]
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - Linux Privilege Escalation
    - Linux Persistence Techniques
    - Compromised Linux Host
asset_type: Endpoint
mitre_attack_id:
    - T1548.003
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/T1548.003/auditd_path_cwd_doas_conf/path_doas.log
          source: auditd
          sourcetype: auditd
      test_type: unit