Sigma rule: Failed NTLM Logins with Different Accounts from Single Source System

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-24319f6c634e, updated 2023-02-24T00:00:00.000Z.

Rule

Title
Failed NTLM Logins with Different Accounts from Single Source System
Status
unsupported
Level
medium
Author
Florian Roth (Nextron Systems)
Date
2017/01/10
Modified
2023/02/24
File
unsupported/windows/win_security_susp_failed_logons_single_source2.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious failed logins with different user accounts from a single source system

Log source

product
windows
service
security

Detection

selection2:
    EventID: 4776
    TargetUserName: '*'
    Workstation: '*'
timeframe: 24h
condition: selection2 | count(TargetUserName) by Workstation > 3

False positives (as the rule lists them)

  • Terminal servers
  • Jump servers
  • Other multiuser systems like Citrix server farms
  • Workstations with frequently changing users

Tags

  • attack.persistence
  • attack.privilege_escalation
  • attack.t1078

MITRE ATT&CK ids this rule names

Related rules

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_source2.yml

Sources and licences

  • SigmaHQ

    "Failed NTLM Logins with Different Accounts from Single Source System" by Florian Roth (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/unsupported/windows/win_security_susp_failed_logons_single_source2.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: Failed NTLM Logins with Different Accounts from Single Source System",
entity page, dataset version ref-24319f6c634e, updated 2023-02-24T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/6309ffc4-8fa2-47cf-96b8-a2f72e58e538 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 6309ffc4-8fa2-47cf-96b8-a2f72e58e538, 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.