Sigma rule: HackTool - Defendnot Installation via PowerShell One-Liner

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-d3fa4ccbd88f, updated 2026-10-18T00:00:00.000Z.

Rule

Title
HackTool - Defendnot Installation via PowerShell One-Liner
Status
experimental
Level
high
Author
Swachchhanda Shrawan Poudel (Nextron Systems)
Date
2026-10-18
File
rules/windows/powershell/powershell_script/posh_ps_hktl_defendnot_installation.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects execution of Defendnot installation via PowerShell one-liner that downloads and executes the Defendnot script from a remote URL.
Defendnot is a hacktool that abuses Microsoft's undocumented WSC API to disable Windows Defender by registering itself as a fake antivirus product.

Log source

product
windows
category
ps_script

Detection

selection:
    - ScriptBlockText|contains: 'https://dnot.sh/'
    - ScriptBlockText|contains|all:
          - '/defendnot'
          - 'github' # covers both api.github.com and raw.githubusercontent.com
condition: selection

False positives (as the rule lists them)

  • Unlikely

Tags

  • attack.defense-impairment
  • attack.t1685

MITRE ATT&CK ids this rule names

Related rules

References

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/powershell/powershell_script/posh_ps_hktl_defendnot_installation.yml

Sources and licences

  • SigmaHQ

    "HackTool - Defendnot Installation via PowerShell One-Liner" by Swachchhanda Shrawan Poudel (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/powershell/powershell_script/posh_ps_hktl_defendnot_installation.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: HackTool - Defendnot Installation via PowerShell One-Liner",
entity page, dataset version ref-d3fa4ccbd88f, updated 2026-10-18T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/50b159ba-a147-40f7-9d11-561e724b8a2e (accessed 2026-11-03).
Underlying source: SigmaHQ rule 50b159ba-a147-40f7-9d11-561e724b8a2e, 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.