IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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File made Immutable by Chattr

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File made Immutable by Chattr

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Detects a file being made immutable using the chattr binary. Making a file immutable means it cannot be deleted or renamed, no link can be created to this file, most of the file’s metadata can not be modified, and the file can not be opened in write mode. Threat actors will commonly utilize this to prevent tampering or modification of their malicious files or any system files they have modified for purposes of persistence (e.g .ssh, /etc/passwd, etc.).

Rule type: eql

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: 33

References: None

Tags:

Elastic
Host
Linux
Threat Detection
Defense Evasion

Version: 101

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

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Rule query

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process where event.type == "start" and user.name == "root" and process.executable : "/usr/bin/chattr" and process.args : ("-*i*", "+*i*") and not process.parent.executable: "/lib/systemd/systemd"

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: File and Directory Permissions Modification
- ID: T1222
- Reference URL: https://attack.mitre.org/techniques/T1222/
Sub-technique:
- Name: Linux and Mac File and Directory Permissions Modification
- ID: T1222.002
- Reference URL: https://attack.mitre.org/techniques/T1222/002/

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