Suspicious Child Process of Notepad++ Updater - GUP.Exe — Sigma Rule

Rule metadata and linked tags

Author: Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: high. Source dates: 2026-02-03 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 0d2b51abae9850b054d7a5e6a7a94ad7f3bbbec8e5e3ba35075c99a5a03ccfb8

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: Suspicious Child Process of Notepad++ Updater - GUP.Exe
id: bb0e87ce-c89f-4857-84fa-095e4483e9cb
status: experimental
description: |
    Detects suspicious child process creation by the Notepad++ updater process (gup.exe).
    This could indicate potential exploitation of the updater component to deliver unwanted malware.
references:
    - https://notepad-plus-plus.org/news/v889-released/
    - https://www.heise.de/en/news/Notepad-updater-installed-malware-11109726.html
    - https://www.rapid7.com/blog/post/tr-chrysalis-backdoor-dive-into-lotus-blossoms-toolkit/
    - https://www.validin.com/blog/exploring_notepad_plus_plus_network_indicators/
    - https://securelist.com/notepad-supply-chain-attack/118708/
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2026-02-03
tags:
    - attack.collection
    - attack.credential-access
    - attack.t1195.002
    - attack.initial-access
    - attack.t1557
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith: '\gup.exe'
    selection_child_img:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\cscript.exe'
            - '\wscript.exe'
            - '\mshta.exe'
    selection_child_cli:
        CommandLine|contains:
            - 'bitsadmin'
            - 'certutil'
            - 'curl'
            - 'finger'
            - 'forfiles'
            - 'regsvr32'
            - 'rundll32'
            - 'wget'
    condition: selection_parent and 1 of selection_child_*
falsepositives:
    - Unlikely
level: high

Original YAML and metadata in JSON

False positives

• Unlikely

Source references

• https://notepad-plus-plus.org/news/v889-released/
• https://www.heise.de/en/news/Notepad-updater-installed-malware-11109726.html
• https://www.rapid7.com/blog/post/tr-chrysalis-backdoor-dive-into-lotus-blossoms-toolkit/
• https://www.validin.com/blog/exploring_notepad_plus_plus_network_indicators/
• https://securelist.com/notepad-supply-chain-attack/118708/