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FortiGate - VPN SSL Settings Modified — Sigma Rule

Sigma rule 8b5dacf2-aeb7-459d-b133-678eb696d410. FortiGate - VPN SSL Settings Modified — Sigma Rule. Detects the modification of VPN SSL Settings (for example, the modification of authentication rules). This behavior was observed in pair with the addition of a VPN SSL Web Portal.

Rule metadata and linked tags

experimentalmediumfortigateeventattack.persistenceattack.initial-accessattack.t1133

Author: Marco Pedrinazzi @pedrinazziM (InTheCyber). Source status: experimental; severity: medium. Source dates: 2025-11-01 / not supplied.

{
  "product": "fortigate",
  "service": "event"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 0c5df7b64121425869ffd9da1fbdf195725d08d307fe500f1f20749f1384db2e

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: FortiGate - VPN SSL Settings Modified
id: 8b5dacf2-aeb7-459d-b133-678eb696d410
status: experimental
description: |
    Detects the modification of VPN SSL Settings (for example, the modification of authentication rules).
    This behavior was observed in pair with the addition of a VPN SSL Web Portal.
references:
    - https://www.fortiguard.com/psirt/FG-IR-24-535
    - https://docs.fortinet.com/document/fortigate/7.6.4/fortios-log-message-reference/398/event
    - https://docs.fortinet.com/document/fortigate/7.6.4/cli-reference/114404382/config-vpn-ssl-settings
    - https://docs.fortinet.com/document/fortigate/7.6.4/fortios-log-message-reference/44546/44546-logid-event-config-attr
author: Marco Pedrinazzi @pedrinazziM (InTheCyber)
date: 2025-11-01
tags:
    - attack.persistence
    - attack.initial-access
    - attack.t1133
logsource:
    product: fortigate
    service: event
detection:
    selection:
        action: 'Edit'
        cfgpath: 'vpn.ssl.settings'
    condition: selection
falsepositives:
    - VPN SSL settings can be changed for legitimate purposes.
level: medium

Original YAML and metadata in JSON

False positives

  • VPN SSL settings can be changed for legitimate purposes.

Source references

Connected ecosystem references

Exact source-tagged techniques

Telemetry review

Read the original logsource above, then inspect the linked detection workspaces for technique-level sensor context. No per-rule telemetry equivalence is inferred.

Pinned research references. No browser attack runner, live simulation result or validated detector is asserted. Source mappings and validation limits are preserved. ATT&CK / Atomic provenance · Detection provenance.