SSH Authorized Keys File Modification

The Secure Shell (SSH) authorized_keys file specifies which users are allowed to log into a server using public key authentication. Adversaries may modify it to maintain persistence on a victim host by adding their own public key(s).

Rule type: new_terms

Rule indices:

auditbeat-*
logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

Domain: Endpoint
OS: Linux
OS: macOS
Use Case: Threat Detection
Tactic: Lateral Movement
Tactic: Persistence
Data Source: Elastic Defend

Version: 206

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

edit

event.category:file and event.type:(change or creation) and
 file.name:("authorized_keys" or "authorized_keys2" or "/etc/ssh/sshd_config" or "/root/.ssh") and
 not process.executable:
             (/Library/Developer/CommandLineTools/usr/bin/git or
              /usr/local/Cellar/maven/*/libexec/bin/mvn or
              /Library/Java/JavaVirtualMachines/jdk*.jdk/Contents/Home/bin/java or
              /usr/bin/vim or
              /usr/local/Cellar/coreutils/*/bin/gcat or
              /usr/bin/bsdtar or
              /usr/bin/nautilus or
              /usr/bin/scp or
              /usr/bin/touch or
              /var/lib/docker/* or
              /usr/bin/google_guest_agent or
              /opt/jc/bin/jumpcloud-agent or
              /opt/puppetlabs/puppet/bin/puppet or
              /usr/bin/chef-client
)

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Account Manipulation
- ID: T1098
- Reference URL: https://attack.mitre.org/techniques/T1098/
Sub-technique:
- Name: SSH Authorized Keys
- ID: T1098.004
- Reference URL: https://attack.mitre.org/techniques/T1098/004/
Tactic:
- Name: Lateral Movement
- ID: TA0008
- Reference URL: https://attack.mitre.org/tactics/TA0008/
Technique:
- Name: Remote Services
- ID: T1021
- Reference URL: https://attack.mitre.org/techniques/T1021/
Sub-technique:
- Name: SSH
- ID: T1021.004
- Reference URL: https://attack.mitre.org/techniques/T1021/004/
Technique:
- Name: Remote Service Session Hijacking
- ID: T1563
- Reference URL: https://attack.mitre.org/techniques/T1563/
Sub-technique:
- Name: SSH Hijacking
- ID: T1563.001
- Reference URL: https://attack.mitre.org/techniques/T1563/001/

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