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Tampering of Shell Command-Line History

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Tampering of Shell Command-Line History

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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:

logs-endpoint.events.*
endgame-*
auditbeat-*
logs-auditd_manager.auditd-*

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: Defense Evasion
Data Source: Elastic Defend
Data Source: Elastic Endgame
Data Source: Auditd Manager

Version: 105

Rule authors:

Elastic

Rule license: Elastic License v2

Setup

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Setup

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 version 8.2. Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate event.ingested to @timestamp. For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html

Rule query

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process where event.action in ("exec", "exec_event", "executed", "process_started") and event.type == "start" and
 (
  ((process.args : ("rm", "echo") or
    (process.args : "ln" and process.args : "-sf" and process.args : "/dev/null") or
    (process.args : "truncate" and process.args : "-s0"))
    and process.args : (".bash_history", "/root/.bash_history", "/home/*/.bash_history","/Users/.bash_history", "/Users/*/.bash_history",
                        ".zsh_history", "/root/.zsh_history", "/home/*/.zsh_history", "/Users/.zsh_history", "/Users/*/.zsh_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&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Indicator Removal
- 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/

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