detect_rtlo_in_process.yml

name: Detect RTLO In Process
id: 22ac27b4-7189-4a4f-9375-b9017c9620d7
version: 2
date: '2023-04-26'
author: Steven Dick
status: production
type: TTP
description: This search is used to detect the abuse of the right-to-left override
  (RTLO or RLO) character (U+202E) RTLO. This technique is used by adversaries to
  disguise a string and/or file name to make it appear benign. The RTLO character
  is a non-printing Unicode character that causes the text that follows it to be displayed
  in reverse.
data_source:
- Sysmon EventID 1
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
  as lastTime from datamodel=Endpoint.Processes where Processes.process!=unknown AND
  Processes.action=allowed by Processes.dest Processes.user Processes.original_file_name
  Processes.parent_process_name Processes.parent_process Processes.process_name Processes.process
  Processes.process_id Processes.process_guid Processes.parent_process_id | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)` | `drop_dm_object_name(Processes)` | regex
  process="\\x{202E}" | rex field=process "(?<RTLO_command_1>.+)(?<RTLO_exist_process>\\x{202E})(?<RTLO_command_2>.+)"
  | eval process_with_RTLO=process | eval process=RTLO_command_1.RTLO_command_2 |
  fields - RTLO* | `detect_rtlo_in_process_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: Implementation in regions that use right to left in native
  language.
references:
- https://attack.mitre.org/techniques/T1036/002/
- https://resources.infosecinstitute.com/topic/spoof-using-right-to-left-override-rtlo-technique-2/
- https://www.trendmicro.com/en_us/research/17/f/following-trail-blacktech-cyber-espionage-campaigns.html
tags:
  analytic_story:
  - Spearphishing Attachments
  asset_type: Endpoint
  confidence: 80
  impact: 50
  message: Suspicious RTLO detected in $process_name$ on endpoint $dest$ by user $user$.
  mitre_attack_id:
  - T1036.002
  - T1036
  observable:
  - name: user
    type: User
    role:
    - Victim
  - name: dest
    type: Endpoint
    role:
    - Victim
  - name: process_name
    type: Process Name
    role:
    - Attacker
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - Processes.dest
  - Processes.user
  - Processes.original_file_name
  - Processes.process_name
  - Processes.process
  - Processes.process_id
  - Processes.process_guid
  - Processes.parent_process_id
  - Processes.parent_process_name
  - Processes.parent_process
  risk_score: 40
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1036.002/outlook_attachment/rtlo_events.log
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
    sourcetype: xmlwineventlog