huntrule

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
AnalysisDetection

ATT&CK techniques

Persistence

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. 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
Suspicious Local Account Creation via Net User in Pre-Ransomware Phase
Suspicious Hidden Local Account Creation via Net User by UAT-8099
Malicious Local Account Creation of Support or Whiteninja via net.exe
Malicious Dynamicweb Unauthenticated Administrator Creation via Setup Default.aspx (via webserver)
Suspicious Hidden Backdoor Account Creation Ending With Dollar Sign (via process_creation)
Malicious User Creation via Commandline (via process_creation)
Suspicious Local Account Creation and Privileged Group Addition via Net.EXE (via process_creation)
Suspicious Hidden Local Account Creation via Dscl (via process_creation)
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
  1. v3
    Candidate ingested via manual entry.2026-07-31
  2. v2
    Candidate ingested via manual entry.2026-07-31
  3. 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.