Sigma rule: User Added To Root/Sudoers Group Using Usermod

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-0041f1fe35c9, updated 2022-12-21T00:00:00.000Z.

Rule

Title: User Added To Root/Sudoers Group Using Usermod
Status: test
Level: medium
Author: TuanLe (GTSC)
Date: 2022-12-21
File: rules/linux/process_creation/proc_creation_lnx_usermod_susp_group.yml
Commit: ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects usage of the "usermod" binary to add users add users to the root or suoders groups

Log source

product: linux
category: process_creation

Detection

selection:
    Image|endswith: '/usermod'
    CommandLine|contains:
        - '-aG root'
        - '-aG sudoers'
condition: selection

False positives (as the rule lists them)

Legitimate administrator activities

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/linux/process_creation/proc_creation_lnx_usermod_susp_group.yml

Sources and licences

SigmaHQ
"User Added To Root/Sudoers Group Using Usermod" by TuanLe (GTSC) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/linux/process_creation/proc_creation_lnx_usermod_susp_group.yml.
Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License
Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: User Added To Root/Sudoers Group Using Usermod",
entity page, dataset version ref-0041f1fe35c9, updated 2022-12-21T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/6a50f16c-3b7b-42d1-b081-0fdd3ba70a73 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 6a50f16c-3b7b-42d1-b081-0fdd3ba70a73, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.