Sigma rule: Potential CVE-2021-42287 Exploitation Attempt

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-8674eca48f57, updated 2023-04-14T00:00:00.000Z.

Rule

Title
Potential CVE-2021-42287 Exploitation Attempt
Status
test
Level
medium
Author
frack113
Date
2021-12-15
Modified
2023-04-14
File
rules-emerging-threats/2021/Exploits/CVE-2021-42287/win_system_exploit_cve_2021_42287.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

The attacker creates a computer object using those permissions with a password known to her.
After that she clears the attribute ServicePrincipalName on the computer object.
Because she created the object (CREATOR OWNER), she gets granted additional permissions and can do many changes to the object.

Log source

product
windows
service
system

Detection

selection:
    Provider_Name: Microsoft-Windows-Directory-Services-SAM  # Active Directory
    EventID:
        - 16990 # Object class and UserAccountControl validation failure
        - 16991 # SAM Account Name validation failure
condition: selection

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.credential-access
  • attack.t1558.003
  • detection.emerging-threats
  • cve.2021-42287

CVEs this rule names

MITRE ATT&CK ids this rule names

Related rules

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-2021-42287/win_system_exploit_cve_2021_42287.yml

Sources and licences

  • SigmaHQ

    "Potential CVE-2021-42287 Exploitation Attempt" by frack113 (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-42287/win_system_exploit_cve_2021_42287.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: Potential CVE-2021-42287 Exploitation Attempt",
entity page, dataset version ref-8674eca48f57, updated 2023-04-14T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/e80a0fee-1a62-4419-b31e-0d0db6e6013a (accessed 2026-11-03).
Underlying source: SigmaHQ rule e80a0fee-1a62-4419-b31e-0d0db6e6013a, 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.