name: Linux Shred Overwrite Command
id: c1952cf1-643c-4965-82de-11c067cbae76
version: 1
date: '2023-04-14'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: This analytic is to detect a shred process to overwrite a files in a
  linux machine. Shred Linux application is designed to overwrite file to hide its
  contents or make the deleted file un-recoverable. Weve seen this technique in industroyer2
  malware that tries to wipe energy facilities of targeted sector as part of its destructive
  attack. It might be some normal user may use this command for valid purposes but
  it is recommended to check what files, disk or folder it tries to shred that might
  be good pivot for incident response in this type of destructive malware.
data_source:
- Sysmon Event ID 1
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
  as lastTime from datamodel=Endpoint.Processes where Processes.process_name =shred
  AND Processes.process IN ("*-n*", "*-u*", "*-z*", "*-s*") by Processes.parent_process_name
  Processes.process_name Processes.process Processes.process_id Processes.parent_process_id
  Processes.process_guid Processes.dest Processes.user | `drop_dm_object_name(Processes)`
  | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `linux_shred_overwrite_command_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: Administrator or network operator can use this application
  for automation purposes. Please update the filter macros to remove false positives.
references:
- https://www.welivesecurity.com/2022/04/12/industroyer2-industroyer-reloaded/
- https://cert.gov.ua/article/39518
tags:
  analytic_story:
  - Industroyer2
  - AwfulShred
  - Linux Privilege Escalation
  - Data Destruction
  - Linux Persistence Techniques
  asset_type: Endpoint
  confidence: 70
  impact: 70
  message: A possible shred overwrite command $process$ executed on $dest$
  mitre_attack_id:
  - T1485
  observable:
  - name: dest
    type: Hostname
    role:
    - Victim
  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: 49
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1485/rm_shred_critical_dir/sysmon_linux.log
    source: Syslog:Linux-Sysmon/Operational
    sourcetype: sysmon_linux