Sigma rule: CVE-2021-31979 CVE-2021-33771 Exploits

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-438c361ff348, updated 2023-08-17T00:00:00.000Z.

Rule

Title
CVE-2021-31979 CVE-2021-33771 Exploits
Status
test
Level
critical
Author
Sittikorn S, frack113
Date
2021-07-16
Modified
2023-08-17
File
rules-emerging-threats/2021/Exploits/CVE-2021-33771/registry_set_cve_2021_31979_cve_2021_33771_exploits.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects patterns as noticed in exploitation of Windows CVE-2021-31979 CVE-2021-33771 vulnerability and DevilsTongue malware by threat group Sourgum

Log source

product
windows
category
registry_set

Detection

selection:
    TargetObject|endswith:
        - CLSID\{CF4CC405-E2C5-4DDD-B3CE-5E7582D8C9FA}\InprocServer32\(Default)
        - CLSID\{7C857801-7381-11CF-884D-00AA004B2E24}\InProcServer32\(Default)
filter:
    Details|endswith:
        - system32\wbem\wmiutils.dll
        - system32\wbem\wbemsvc.dll
condition: selection and not filter

False positives (as the rule lists them)

  • Unlikely

Tags

  • attack.initial-access
  • attack.execution
  • attack.credential-access
  • attack.t1566
  • attack.t1203
  • cve.2021-33771
  • cve.2021-31979
  • 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-2021-33771/registry_set_cve_2021_31979_cve_2021_33771_exploits.yml

Sources and licences

  • SigmaHQ

    "CVE-2021-31979 CVE-2021-33771 Exploits" by Sittikorn S, frack113 (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-33771/registry_set_cve_2021_31979_cve_2021_33771_exploits.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: CVE-2021-31979 CVE-2021-33771 Exploits",
entity page, dataset version ref-438c361ff348, updated 2023-08-17T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/32b5db62-cb5f-4266-9639-0fa48376ac00 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 32b5db62-cb5f-4266-9639-0fa48376ac00, 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.