Sigma rule: Invalid Users Failing To Authenticate From Source Using Kerberos

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-91d2b494261d, updated 2023-03-13T00:00:00.000Z.

Rule

Title
Invalid Users Failing To Authenticate From Source Using Kerberos
Status
unsupported
Level
medium
Author
Mauricio Velazco, frack113
Date
2021/06/01
Modified
2023/03/13
File
unsupported/windows/win_security_susp_failed_logons_single_source_kerberos3.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects failed logins with multiple invalid domain accounts from a single source system using the Kerberos protocol.

Log source

product
windows
service
security

Detection

selection:
    EventID: 4768
    Status: '0x6'
filter_computer:
    TargetUserName|endswith: '$'
timeframe: 24h
condition: selection and not filter_computer | count(TargetUserName) by IpAddress > 10

False positives (as the rule lists them)

  • Vulnerability scanners
  • Misconfigured systems
  • Remote administration tools
  • VPN terminators
  • Multiuser systems like Citrix server farms

Tags

  • attack.t1110.003
  • attack.initial_access
  • attack.privilege_escalation

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/unsupported/windows/win_security_susp_failed_logons_single_source_kerberos3.yml

Sources and licences

  • SigmaHQ

    "Invalid Users Failing To Authenticate From Source Using Kerberos" by Mauricio Velazco, frack113 (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/unsupported/windows/win_security_susp_failed_logons_single_source_kerberos3.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: Invalid Users Failing To Authenticate From Source Using Kerberos",
entity page, dataset version ref-91d2b494261d, updated 2023-03-13T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/bc93dfe6-8242-411e-a2dd-d16fa0cc8564 (accessed 2026-11-03).
Underlying source: SigmaHQ rule bc93dfe6-8242-411e-a2dd-d16fa0cc8564, 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.