Tampering of Bash Command-Line History

Elastic Stack Serverless Security

Adversaries may attempt to clear or disable the Bash command-line history in an attempt to evade detection or forensic investigations.

Rule type: eql

Rule indices:

• auditbeat-*
• logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

• Elastic
• Host
• Linux
• Threat Detection
• Defense Evasion

Version: 7

Rule authors:

• Elastic

Rule license: Elastic License v2

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define event.ingested and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate event.ingested to @timestamp for this rule to work.

process where event.type in ("start", "process_started") and
 (
  (process.args : ("rm", "echo") and process.args : (".bash_history", "/root/.bash_history", "/home/*/.bash_history")) or
  (process.name : "history" and process.args : "-c") or
  (process.args : "export" and process.args : ("HISTFILE=/dev/null", "HISTFILESIZE=0")) or
  (process.args : "unset" and process.args : "HISTFILE") or
  (process.args : "set" and process.args : "history" and process.args : "+o")
 )

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Defense Evasion
  • ID: TA0005
  • Reference URL: https://attack.mitre.org/tactics/TA0005/

• Technique:

  • Name: Indicator Removal on Host
  • ID: T1070
  • Reference URL: https://attack.mitre.org/techniques/T1070/

• Sub-technique:

  • Name: Clear Command History
  • ID: T1070.003
  • Reference URL: https://attack.mitre.org/techniques/T1070/003/