name: Linux PHP Privilege Escalation
id: 4fc4c031-e5be-4cc0-8cf9-49f9f507bcb5
version: 2
date: '2024-05-19'
author: Gowthamaraj Rajendran, Splunk
status: production
type: Anomaly
description: The following analytic detects the execution of PHP commands with elevated
  privileges on a Linux system. It identifies instances where PHP is used in conjunction
  with 'sudo' and 'system' commands, indicating an attempt to run system commands
  as the root user. This detection leverages data from Endpoint Detection and Response
  (EDR) agents, focusing on process command-line arguments. This activity is significant
  because it can indicate an attempt to escalate privileges, potentially leading to
  full root access. If confirmed malicious, this could allow an attacker to execute
  arbitrary commands with root privileges, compromising the entire system.
data_source:
- Sysmon for Linux EventID 1
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
  as lastTime from datamodel=Endpoint.Processes where Processes.process="*php*-r*"
  AND Processes.process="*system*" AND Processes.process="*sudo*" by Processes.dest
  Processes.user Processes.parent_process_name Processes.process_name Processes.process
  Processes.process_id Processes.parent_process_id Processes.process_guid | `drop_dm_object_name(Processes)`
  | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `linux_php_privilege_escalation_filter`'
how_to_implement: The detection is based on data that originates from Endpoint Detection
  and Response (EDR) agents. These agents are designed to provide security-related
  telemetry from the endpoints where the agent is installed. To implement this search,
  you must ingest logs that contain the process GUID, process name, and parent process.
  Additionally, you must ingest complete command-line executions. These logs must
  be processed using the appropriate Splunk Technology Add-ons that are specific to
  the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint`
  data model. Use the Splunk Common Information Model (CIM) to normalize the field
  names and speed up the data modeling process.
known_false_positives: False positives may be present, filter as needed.
references:
- https://gtfobins.github.io/gtfobins/php/
- https://en.wikipedia.org/wiki/PHP
tags:
  analytic_story:
  - Linux Privilege Escalation
  - Linux Living Off The Land
  asset_type: Endpoint
  confidence: 50
  impact: 60
  message: An instance of $parent_process_name$ spawning $process_name$ was identified
    on endpoint $dest$
  mitre_attack_id:
  - T1548.003
  - T1548
  observable:
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: parent_process_name
    type: Process
    role:
    - Parent Process
  - name: process_name
    type: Process
    role:
    - Child Process
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - Processes.dest
  - Processes.user
  - Processes.parent_process_name
  - Processes.process_name
  - Processes.process
  - Processes.process_id
  - Processes.parent_process_id
  risk_score: 30
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: 
      https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1548/php/sysmon_linux.log
    source: Syslog:Linux-Sysmon/Operational
    sourcetype: sysmon:linux
    update_timestamp: true