Linux: chattr Used to Remove Immutable File Attribute

Flags Linux process use of chattr with -i to remove the immutable file attribute.

FreeReviewedSigma · Medium · v3

Product: linux
Category: process_creation
Author: Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-09-15
Updated: 2026-07-31

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1222.002Linux and Mac Permissions
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags process executions where the command invokes the chattr utility with the immutable-attribute removal option ("-i"), indicating an attempt to alter file protection. Removing immutability can help attackers modify or delete files that were intended to resist tampering, supporting defense-impairment and persistence activities. It relies on Linux process creation telemetry, matching the chattr executable path and the presence of the " -i " argument in the command line.

Reporting behind it

Related detections7 linkedT1222.002 — drag to rearrange

Suspicious Making a File Executable in a Temp Directory (via process_creation)

Suspicious File Immutability Manipulation via chattr

Suspicious Download to tmp Followed by chmod Execution on Linux

Malicious Immutable Flag on SSH authorized_keys via chattr

Linux chmod Process Commandlines Targeting Sensitive Directory Paths

Linux auditd: chmod/chown process execution indicating file or folder permission changes

Linux auditd: Detect chattr -i removing immutable file attribute

Linux: chattr Used to Remove Immutable File Attribute

Pivot detection · T1222.002 · 7 related

Changelog

v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

linux-chattr-i-used-to-remove-immutable-file-attribute-34979410

title: "Linux: chattr Used to Remove Immutable File Attribute"
id: f207b146-5627-421a-ab82-7d439ba4d935
related:
  - id: a5b977d6-8a81-4475-91b9-49dbfcd941f7
    type: derived
  - id: 34979410-e4b5-4e5d-8cfb-389fdff05c12
    type: derived
status: test
description: This rule flags process executions where the command invokes the chattr utility with the immutable-attribute removal option ("-i"), indicating an attempt to alter file protection. Removing immutability can help attackers modify or delete files that were intended to resist tampering, supporting defense-impairment and persistence activities. It relies on Linux process creation telemetry, matching the chattr executable path and the presence of the " -i " argument in the command line.
references:
  - https://www.trendmicro.com/en_us/research/22/i/how-malicious-actors-abuse-native-linux-tools-in-their-attacks.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules/linux/process_creation/proc_creation_lnx_chattr_immutable_removal.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-09-15
tags:
  - attack.defense-impairment
  - attack.t1222.002
logsource:
  product: linux
  category: process_creation
detection:
  selection:
    Image|endswith: /chattr
    CommandLine|contains: " -i "
  condition: selection
falsepositives:
  - Administrator interacting with immutable files (e.g. for instance backups).
level: medium
license: DRL-1.1

Convert

This rule as a query you can run. Uses no unlock credit.

SplunkSPL