windows_process_writing_file_to_world_writable_path.yml

name: Windows Process Writing File to World Writable Path
id: c051b68c-60f7-4022-b3ad-773bec7a225b
version: 1
date: '2024-04-17'
author: Michael Haag, Splunk
data_source: []
type: Hunting
status: production
description: The following analytic identifies a process writing a file, specifically a .txt, to a world writable path. This technique is used by adversaries to deliver payloads to a system. It is not common for living off the land binaries to write to these paths.
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where Filesystem.file_name=*.txt Filesystem.file_path IN ("*\\Windows\\Tasks\\*", "*\\Windows\\Temp\\*", "*\\Windows\\tracing\\*", "*\\Windows\\PLA\\Reports\\*", "*\\Windows\\PLA\\Rules\\*", "*\\Windows\\PLA\\Templates\\*", "*\\Windows\\PLA\\Reports\\en-US\\*", "*\\Windows\\PLA\\Rules\\en-US\\*", "*\\Windows\\Registration\\CRMLog\\*", "*\\Windows\\System32\\Tasks\\*", "*\\Windows\\System32\\Com\\dmp\\*", "*\\Windows\\System32\\LogFiles\\WMI\\*", "*\\Windows\\System32\\Microsoft\\Crypto\\RSA\\MachineKeys\\*", "*\\Windows\\System32\\spool\\PRINTERS\\*", "*\\Windows\\System32\\spool\\SERVERS\\*", "*\\Windows\\System32\\spool\\drivers\\color\\*", "*\\Windows\\System32\\Tasks\\Microsoft\\Windows\\RemoteApp and Desktop Connections Update\\*", "*\\Windows\\SysWOW64\\Tasks\\*", "*\\Windows\\SysWOW64\\Com\\dmp\\*", "*\\Windows\\SysWOW64\\Tasks\\Microsoft\\Windows\\PLA\\*", "*\\Windows\\SysWOW64\\Tasks\\Microsoft\\Windows\\RemoteApp and Desktop Connections Update\\*", "*\\Windows\\SysWOW64\\Tasks\\Microsoft\\Windows\\PLA\\System\\*") by Filesystem.dest, Filesystem.user, Filesystem.file_name Filesystem.file_path 
  | `drop_dm_object_name("Filesystem")`
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)` | `windows_process_writing_file_to_world_writable_path_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 file creation event, process name, file path and, file name.
  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 `Filesystem` 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 occur if legitimate software writes to these paths. Modify the search to include additional file name extensions. To enhance it further, adding a join on Processes.process_name may assist with restricting the analytic to specific process names. Investigate the process and file to determine if it is malicious.
references:
- https://research.splunk.com/endpoint/efbcf8ee-bc75-47f1-8985-a5c638c4faf0/
tags:
  analytic_story:
  - APT29 Diplomatic Deceptions with WINELOADER
  asset_type: Endpoint
  confidence: 50
  impact: 50
  message: A process wrote a file name- [$file_name$] to a world writable file path [$file_path$] on host- [$dest$].
  mitre_attack_id:
  - T1218.005
  observable:
  - name: dest
    type: Endpoint
    role:
    - Victim
  - name: file_name
    type: File
    role:
    - Attacker
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - dest
  - user
  - file_name
  - file_path
  risk_score: 25
  security_domain: endpoint
  cve: []
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.005/atomic_red_team/mshta_tasks_windows-sysmon.log
    sourcetype: xmlwineventlog
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational