Potential CVE-2023-27997 Exploitation Indicators

Description

Detects indicators of potential exploitation of CVE-2023-27997 in Frotigate weblogs. To avoid false positives it is best to look for successive requests to the endpoints mentioned as well as weird values of the "enc" parameter

Query · sigma

selection_uri:
  cs-method:
  - GET
  - POST
  cs-uri-query|contains:
  - /remote/hostcheck_validate
  - /remote/logincheck
selection_keywords:
- enc=
condition: all of selection_*

Known false positives

  • Unknown
Raw source Potential CVE-2023-27997 Exploitation Indicators · Sigma
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Published by SigmaHQ/sigma ↗, licensed under Detection Rule License 1.1 ↗. Reproduced here unmodified. 
title: Potential CVE-2023-27997 Exploitation Indicators
id: 31e4e649-7394-4fd2-9ae7-dbc61eebb550
status: test
description: |
    Detects indicators of potential exploitation of CVE-2023-27997 in Frotigate weblogs.
    To avoid false positives it is best to look for successive requests to the endpoints mentioned as well as weird values of the "enc" parameter
references:
    - https://blog.lexfo.fr/Forensics-xortigate-notice.html
    - https://blog.lexfo.fr/xortigate-cve-2023-27997.html
    - https://research.kudelskisecurity.com/2023/06/12/cve-2023-27997-fortigate-ssl-vpn/
    - https://labs.watchtowr.com/xortigate-or-cve-2023-27997/
author: Sergio Palacios Dominguez, Nasreddine Bencherchali (Nextron Systems)
date: 2023-07-28
tags:
    - attack.initial-access
    - attack.t1190
    - cve.2023-27997
    - detection.emerging-threats
logsource:
    category: webserver
detection:
    selection_uri:
        cs-method:
            - 'GET'
            - 'POST'
        cs-uri-query|contains:
            - '/remote/hostcheck_validate'
            - '/remote/logincheck'
    selection_keywords:
        - 'enc='
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium

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