Sigma rule: Fortinet CVE-2021-22123 Exploitation

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-3104d233831b, updated 2023-01-02T00:00:00.000Z.

Rule

Title
Fortinet CVE-2021-22123 Exploitation
Status
test
Level
critical
Author
Bhabesh Raj, Florian Roth
Date
2021-08-19
Modified
2023-01-02
File
rules-emerging-threats/2021/Exploits/CVE-2021-22123/web_cve_2021_22123_fortinet_exploit.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects CVE-2021-22123 exploitation attempt against Fortinet WAFs

Log source

category
webserver

Detection

selection:
    cs-uri-query|contains: '/api/v2.0/user/remoteserver.saml'
    cs-method: POST
filter1:
    cs-referer|contains: '/root/user/remote-user/saml-user/'
filter2:
    cs-referer: null
condition: selection and not filter1 and not filter2

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.initial-access
  • attack.t1190
  • cve.2021-22123
  • detection.emerging-threats

CVEs this rule names

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-22123/web_cve_2021_22123_fortinet_exploit.yml

Sources and licences

  • SigmaHQ

    "Fortinet CVE-2021-22123 Exploitation" by Bhabesh Raj, Florian Roth (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-22123/web_cve_2021_22123_fortinet_exploit.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Fortinet CVE-2021-22123 Exploitation",
entity page, dataset version ref-3104d233831b, updated 2023-01-02T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/f425637f-891c-4191-a6c4-3bb1b70513b4 (accessed 2026-11-03).
Underlying source: SigmaHQ rule f425637f-891c-4191-a6c4-3bb1b70513b4, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.