huntrule

FortiGate: Administrator Account Added via system.admin Events

Alerts on FortiGate events that add a new administrator account in system.admin.

FreeReviewedSigma · Medium · v2
Product
fortigate
Service
event
Author
Marco Pedrinazzi (@pedrinazziM) (InTheCyber) (SigmaHQ), DRL 1.1
Published
2025-11-01
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 flags FortiGate event logs indicating an administrator account was added under the system.admin configuration path. Creating or modifying admin accounts is a common persistence technique, allowing an attacker to regain access after initial compromise. The detection relies on FortiGate event telemetry containing the account-creation action and the cfgpath value for system.admin.

Reporting behind it

Related detections9 linkedT1136.001 — drag to rearrange
Suspicious Local Administrator Account Creation via Net Command via Process Creation (via process_creation)
Suspicious Rogue Machine Account Creation via Powermad New-MachineAccount
Malicious Local Administrator Account Added via net localgroup (via process_creation)
Malicious Switch User to Rogue Root-Equivalent Account troot (via process_creation)
Malicious Rogue F5 BIG-IP Administrator Account Creation via tmsh (via process_creation)
Suspicious Hidden Local Account Creation SqlDbAdmin via Process Creation
PowerShell Local Account Creation With Self-Deleting Script
Suspicious Creation of ctxsvc Local Account via net Command
Suspicious Local Administrator Account Addition via net localgroup
FortiGate: Administrator Account Added via system.admin Events
Pivot detection · T1136.001 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. 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.