linux_account_manipulation_of_ssh_config_and_keys.yml

name: Linux Account Manipulation Of SSH Config and Keys
id: 73a56508-1cf5-4df7-b8d9-5737fbdc27d2
version: 2
date: '2023-04-27'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: This analytic is to detect a deletion of ssh key in a linux machine.
  attacker may delete or modify ssh key to impair some security features or act as
  defense evasion in compromised linux machine. This Anomaly can be also a good indicator
  of a malware trying to wipe or delete several files in a compromised host as part
  of its destructive payload like what acidrain malware does in linux or router machines.
  This detection can be a good pivot to check what process and user tries to delete
  this type of files which is not so common and need further investigation.
data_source:
- Sysmon for Linux EventID 11
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
  as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.action=deleted AND
  Filesystem.file_path IN ("/etc/ssh/*", "~/.ssh/*") by _time span=1h Filesystem.file_name
  Filesystem.file_path Filesystem.dest Filesystem.process_guid Filesystem.action |
  `drop_dm_object_name(Filesystem)` 
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)`| `linux_account_manipulation_of_ssh_config_and_keys_filter`'
how_to_implement: To successfully implement this search, you need to be ingesting
  logs with the process name, parent process, and command-line executions from your
  endpoints. If you are using Sysmon, you can use the Add-on for Linux Sysmon from
  Splunkbase.
known_false_positives: Administrator or network operator can execute this command.
  Please update the filter macros to remove false positives.
references:
- https://www.sentinelone.com/labs/acidrain-a-modem-wiper-rains-down-on-europe/
tags:
  analytic_story:
  - AcidRain
  asset_type: Endpoint
  confidence: 70
  impact: 70
  message: SSH Config and keys are deleted on $dest$ by Process GUID - $process_guid$
  mitre_attack_id:
  - T1485
  - T1070.004
  - T1070
  observable:
  - name: dest
    type: Hostname
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - Filesystem.dest
  - Filesystem.file_create_time
  - Filesystem.file_name
  - Filesystem.process_guid
  - Filesystem.file_path
  - Filesystem.action
  risk_score: 49
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/acidrain/sysmon_linux.log
    source: Syslog:Linux-Sysmon/Operational
    sourcetype: sysmon_linux