Enable LM Hash Storage — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2023-12-15 / not supplied.

{
  "product": "windows",
  "category": "registry_set"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 523c6e0cde1c6b8bad44be0c366f723573b387644c859c4c8b296a085f733308

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Enable LM Hash Storage
id: c420410f-c2d8-4010-856b-dffe21866437
related:
    - id: 98dedfdd-8333-49d4-9f23-d7018cccae53 # process_creation
      type: similar
status: test
description: |
    Detects changes to the "NoLMHash" registry value in order to allow Windows to store LM Hashes.
    By setting this registry value to "0" (DWORD), Windows will be allowed to store a LAN manager hash of your password in Active Directory and local SAM databases.
references:
    - https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-347a
    - https://learn.microsoft.com/en-us/troubleshoot/windows-server/windows-security/prevent-windows-store-lm-hash-password
    - https://www.sans.org/blog/protecting-privileged-domain-accounts-lm-hashes-the-good-the-bad-and-the-ugly/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-12-15
tags:
    - attack.persistence
    - attack.defense-impairment
    - attack.t1112
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        TargetObject|endswith: 'System\CurrentControlSet\Control\Lsa\NoLMHash'
        Details: 'DWORD (0x00000000)'
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-347a
• https://learn.microsoft.com/en-us/troubleshoot/windows-server/windows-security/prevent-windows-store-lm-hash-password
• https://www.sans.org/blog/protecting-privileged-domain-accounts-lm-hashes-the-good-the-bad-and-the-ugly/