name: Linux Possible Ssh Key File Creation
id: c04ef40c-72da-11ec-8eac-acde48001122
version: 1
date: '2022-01-11'
author: Teoderick Contreras, Splunk
type: Anomaly
datamodel:
- Endpoint
description: This analytic is to look for possible ssh key file creation on ~/.ssh/
  folder. This technique is commonly abused by threat actors and adversaries to gain
  persistence and privilege escalation to the targeted host. by creating ssh private
  and public key and passing the public key to the attacker server. threat actor can
  access remotely the machine using openssh daemon service.
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
  as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_path IN ("*/.ssh*")
  by Filesystem.dest Filesystem.file_name Filesystem.process_guid Filesystem.file_path
  | `drop_dm_object_name(Filesystem)` | `security_content_ctime(lastTime)` | `security_content_ctime(firstTime)`
  | `linux_possible_ssh_key_file_creation_filter`'
how_to_implement: To successfully implement this search, you need to be ingesting
  logs with the file name, file path, and process_guid 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 create file in ~/.ssh
  folders for automation purposes. Please update the filter macros to remove false
  positives.
references:
- https://www.hackingarticles.in/ssh-penetration-testing-port-22/
- https://attack.mitre.org/techniques/T1098/004/
tags:
  analytic_story:
  - Linux Privilege Escalation
  - Linux Persistence Techniques
  - Linux Living Off The Land
  automated_detection_testing: passed
  cis20:
  - CIS 3
  - CIS 5
  - CIS 16
  confidence: 60
  context:
  - Source:Endpoint
  - Stage:Privilege Escalation
  - Stage:Persistence
  dataset:
  - https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1098.004/ssh_authorized_keys/sysmon_linux.log
  impact: 60
  kill_chain_phases:
  - Exploitation
  message: A file $file_name$ is created in $file_path$ on $dest$
  mitre_attack_id:
  - T1098.004
  - T1098
  nist:
  - DE.CM
  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
  risk_score: 36
  security_domain: endpoint
  asset_type: Endpoint