Sigma rule: NTLM Brute Force

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-9b4573b9d9db, updated 2022-02-02T00:00:00.000Z.

Rule

Title: NTLM Brute Force
Status: test
Level: medium
Author: Jerry Shockley '@jsh0x'
Date: 2022-02-02
File: rules/windows/builtin/ntlm/win_susp_ntlm_brute_force.yml
Commit: ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects common NTLM brute force device names

Log source

product: windows
service: ntlm
definition: Requires events from Microsoft-Windows-NTLM/Operational

Detection

selection:
    EventID: 8004
devicename:
    WorkstationName:
        - 'Rdesktop'
        - 'Remmina'
        - 'Freerdp'
        - 'Windows7'
        - 'Windows8'
        - 'Windows2012'
        - 'Windows2016'
        - 'Windows2019'
condition: selection and devicename

False positives (as the rule lists them)

Systems with names equal to the spoofed ones used by the brute force tools

MITRE ATT&CK ids this rule names

T1110

References

https://www.varonis.com/blog/investigate-ntlm-brute-force

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/builtin/ntlm/win_susp_ntlm_brute_force.yml

Sources and licences

SigmaHQ
"NTLM Brute Force" by Jerry Shockley '@jsh0x' (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/builtin/ntlm/win_susp_ntlm_brute_force.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: NTLM Brute Force",
entity page, dataset version ref-9b4573b9d9db, updated 2022-02-02T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/9c8acf1a-cbf9-4db6-b63c-74baabe03e59 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 9c8acf1a-cbf9-4db6-b63c-74baabe03e59, 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.