FortiGate SSO Login Followed by Administrator Account Creation

[metadata]
creation_date = "2026/01/28"
integration = ["fortinet_fortigate"]
maturity = "production"
updated_date = "2026/04/10"

[rule]
author = ["Elastic"]
description = """
This rule detects a FortiCloud SSO login followed by administrator account creation on the same FortiGate device
within 15 minutes. This sequence is a high-confidence indicator of the FG-IR-26-060 attack pattern, where threat
actors authenticate via SAML-based SSO bypass and immediately create local administrator accounts for persistence.
"""
from = "now-30m"
index = ["logs-fortinet_fortigate.*"]
interval = "10m"
language = "eql"
license = "Elastic License v2"
name = "FortiGate SSO Login Followed by Administrator Account Creation"
note = """## Triage and analysis

### Investigating FortiGate SSO Login Followed by Administrator Account Creation

This alert indicates that a FortiCloud SSO login was followed by an administrator account creation event on the same FortiGate device within 15 minutes. This two-event sequence is the core attack pattern observed in the FG-IR-26-060 campaign.

The attack flow is: authenticate via FortiCloud SSO using a crafted SAML assertion, then immediately create local administrator accounts to maintain access even after the SSO vulnerability is patched.

### Possible investigation steps

- Review the SSO login event for the FortiCloud account used and the source IP. Determine whether the SSO account belongs to the organization.
- Check the admin creation event for the names of accounts created and the access profiles assigned (especially super_admin).
- Assess the timing between events. In the observed campaign, admin creation occurs within seconds of SSO login. A tight time correlation is a strong indicator of compromise.
- Review `observer.name` to identify the targeted device and verify whether FortiCloud SSO is intentionally enabled. Run `get system admin` to list all current administrator accounts.
- Check whether the same SSO account or source IP targeted other devices. Look for configuration exports, firewall policy changes, or VPN modifications following the admin creation.

### False positive analysis

- An authorized administrator logging in via FortiCloud SSO and creating a new admin account as part of normal operations.
- Initial device onboarding where SSO login and account setup occur in the same session.

### Response and remediation

- If unauthorized, delete all administrator accounts created during the session and disable FortiCloud SSO immediately.
- Restore configuration from a known-clean backup and rotate all credentials including LDAP/AD accounts connected to the device.
- Upgrade FortiOS to a patched version and engage incident response for the affected device and any downstream systems.
- If the activity is expected, document the administrative session and verify it was authorized. Consider creating accounts through a separate session to avoid triggering this correlation."""
references = [
    "https://www.fortiguard.com/psirt/FG-IR-26-060",
    "https://www.fortinet.com/blog/psirt-blogs/analysis-of-sso-abuse-on-fortios",
    "https://www.elastic.co/docs/reference/integrations/fortinet_fortigate",
    "https://www.cisa.gov/news-events/alerts/2026/01/28/fortinet-releases-guidance-address-ongoing-exploitation-authentication-bypass-vulnerability-cve-2026",
]
risk_score = 73
rule_id = "e3a7b1c2-5d9f-4e8a-b6c3-2f1d4e5a6b7c"
severity = "high"
tags = [
    "Use Case: Threat Detection",
    "Tactic: Persistence",
    "Tactic: Initial Access",
    "Resources: Investigation Guide",
    "Domain: Network",
    "Domain: Identity",
    "Data Source: Fortinet",
    "Data Source: Fortinet FortiGate",
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
sequence by observer.name with maxspan=15m
  [authentication where data_stream.dataset == "fortinet_fortigate.log" and
    event.action == "login" and event.outcome == "success" and
    (fortinet.firewall.method == "sso" or fortinet.firewall.ui like~ "sso*")]
  [any where data_stream.dataset == "fortinet_fortigate.log" and
    event.code == "0100044547" and
    fortinet.firewall.cfgpath == "system.admin" and
    fortinet.firewall.action == "Add"]
'''


[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1136"
name = "Create Account"
reference = "https://attack.mitre.org/techniques/T1136/"

[[rule.threat.technique.subtechnique]]
id = "T1136.001"
name = "Local Account"
reference = "https://attack.mitre.org/techniques/T1136/001/"

[rule.threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"

[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1190"
name = "Exploit Public-Facing Application"
reference = "https://attack.mitre.org/techniques/T1190/"

[rule.threat.tactic]
id = "TA0001"
name = "Initial Access"
reference = "https://attack.mitre.org/tactics/TA0001/"