Linux auditd: New user account creation via useradd (ADD_USER/SYSCALL)

Flags Linux auditd evidence of new local user accounts created using useradd.

FreeReviewedSigma · Medium · v3

Product: linux
Service: auditd
Author: Marie Euler, Pawel Mazur (SigmaHQ), DRL 1.1
Published: 2020-05-18
Updated: 2026-07-31

ATT&CK techniques

Persistence

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1136.001Local Account
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies creation of a new local user account by correlating auditd events where a useradd-related syscall is recorded and an ADD_USER record is present. Attackers may use newly created accounts for persistence without needing remote access tools. The detection relies on Linux auditd telemetry containing SYSCALL events whose executable path ends with /useradd and corresponding ADD_USER audit records.

Reporting behind it

Related detections9 linkedT1136.001 — drag to rearrange

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Suspicious Hidden Backdoor Account Creation Ending With Dollar Sign (via process_creation)

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Suspicious Local Account Creation and Privileged Group Addition via Net.EXE (via process_creation)

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Suspicious Local Account Creation on Linux (via process_creation)

Linux auditd: New user account creation via useradd (ADD_USER/SYSCALL)

Pivot detection · T1136.001 · 9 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-auditd-new-user-account-creation-via-useradd-syscall-or-add-user-audit-eve-759d0d51

title: "Linux auditd: New user account creation via useradd (ADD_USER/SYSCALL)"
id: d63e3ac1-2ff4-43f7-894f-3d7cb144bb43
status: test
description: This rule identifies creation of a new local user account by correlating auditd events where a useradd-related syscall is recorded and an ADD_USER record is present. Attackers may use newly created accounts for persistence without needing remote access tools. The detection relies on Linux auditd telemetry containing SYSCALL events whose executable path ends with /useradd and corresponding ADD_USER audit records.
references:
  - https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/security_guide/sec-understanding_audit_log_files
  - https://access.redhat.com/articles/4409591#audit-record-types-2
  - https://www.youtube.com/watch?v=VmvY5SQm5-Y&ab_channel=M45C07
  - https://github.com/SigmaHQ/sigma/blob/master/rules/linux/auditd/syscall/lnx_auditd_create_account.yml
author: Marie Euler, Pawel Mazur, Huntrule Team
date: 2020-05-18
modified: 2022-12-20
tags:
  - attack.t1136.001
  - attack.persistence
logsource:
  product: linux
  service: auditd
detection:
  selection_syscall_record_type:
    type: SYSCALL
    exe|endswith: /useradd
  selection_add_user_record_type:
    type: ADD_USER
  condition: 1 of selection_*
falsepositives:
  - Admin activity
level: medium
license: DRL-1.1
related:
  - id: 759d0d51-bc99-4b5e-9add-8f5b2c8e7512
    type: derived

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