Sigma rule: NTLMv1 Logon Between Client and Server

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-404267ab70e9, updated 2023-06-06T00:00:00.000Z.

Rule

Title: NTLMv1 Logon Between Client and Server
Status: test
Level: medium
Author: Tim Shelton, Nasreddine Bencherchali (Nextron Systems)
Date: 2022-04-26
Modified: 2023-06-06
File: rules/windows/builtin/system/lsasrv/win_system_lsasrv_ntlmv1.yml
Commit: ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the reporting of NTLMv1 being used between a client and server. NTLMv1 is insecure as the underlying encryption algorithms can be brute-forced by modern hardware.

Log source

product: windows
service: system

Detection

selection:
    Provider_Name: "LsaSrv"
    EventID:
        - 6038
        - 6039
condition: selection

False positives (as the rule lists them)

Environments that use NTLMv1

MITRE ATT&CK ids this rule names

T1550.002

References

https://github.com/nasbench/EVTX-ETW-Resources/blob/f1b010ce0ee1b71e3024180de1a3e67f99701fe4/ETWProvidersManifests/Windows10/22H2/W10_22H2_Pro_20230321_19045.2728/WEPExplorer/LsaSrv.xml

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/system/lsasrv/win_system_lsasrv_ntlmv1.yml

Sources and licences

SigmaHQ
"NTLMv1 Logon Between Client and Server" by Tim Shelton, Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/builtin/system/lsasrv/win_system_lsasrv_ntlmv1.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: NTLMv1 Logon Between Client and Server",
entity page, dataset version ref-404267ab70e9, updated 2023-06-06T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/e9d4ab66-a532-4ef7-a502-66a9e4a34f5d (accessed 2026-11-03).
Underlying source: SigmaHQ rule e9d4ab66-a532-4ef7-a502-66a9e4a34f5d, 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.