Sigma rule: Potential Ransomware Activity Using LegalNotice Message

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-9bc59908b1bd, updated 2023-08-17T00:00:00.000Z.

Rule

Title: Potential Ransomware Activity Using LegalNotice Message
Status: test
Level: high
Author: frack113
Date: 2022-12-11
Modified: 2023-08-17
File: rules/windows/registry/registry_set/registry_set_legalnotice_susp_message.yml
Commit: ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detect changes to the "LegalNoticeCaption" or "LegalNoticeText" registry values where the message set contains keywords often used in ransomware ransom messages

Log source

product: windows
category: registry_set

Detection

selection:
    TargetObject|contains:
        - '\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\LegalNoticeCaption'
        - '\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\LegalNoticeText'
    Details|contains:
        - 'encrypted'
        - 'Unlock-Password'
        - 'paying'
condition: selection

False positives (as the rule lists them)

Unknown

MITRE ATT&CK ids this rule names

T1491.001

References

https://github.com/redcanaryco/atomic-red-team/blob/5c1e6f1b4fafd01c8d1ece85f510160fc1275fbf/atomics/T1491.001/T1491.001.md

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/registry/registry_set/registry_set_legalnotice_susp_message.yml

Sources and licences

SigmaHQ
"Potential Ransomware Activity Using LegalNotice Message" by frack113 (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/registry/registry_set/registry_set_legalnotice_susp_message.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: Potential Ransomware Activity Using LegalNotice Message",
entity page, dataset version ref-9bc59908b1bd, updated 2023-08-17T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/8b9606c9-28be-4a38-b146-0e313cc232c1 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 8b9606c9-28be-4a38-b146-0e313cc232c1, 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.