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Detection rules › Sigma

Suspicious Child Process of Notepad++ Updater - GUP.Exe

Status
experimental
Severity
high
Log source
product windows, category process_creation
Author
Swachchhanda Shrawan Poudel (Nextron Systems)
Source
github.com/SigmaHQ/sigma

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.

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1195.002 Supply Chain Compromise: Compromise Software Supply Chain
Credential AccessT1557 Adversary-in-the-Middle
CollectionT1557 Adversary-in-the-Middle

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

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

Stages and Predicates

Stage 0: condition

selection_parent and 1 of selection_child_*

Stage 1: selection_parent

selection_parent:
    ParentImage|endswith: '\gup.exe'

Stage 2: selection_child_img

selection_child_img:
    Image|endswith:
        - '\cmd.exe'
        - '\powershell.exe'
        - '\pwsh.exe'
        - '\cscript.exe'
        - '\wscript.exe'
        - '\mshta.exe'

Stage 3: selection_child_cli

selection_child_cli:
    CommandLine|contains:
        - 'bitsadmin'
        - 'certutil'
        - 'curl'
        - 'finger'
        - 'forfiles'
        - 'regsvr32'
        - 'rundll32'
        - 'wget'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • bitsadmin corpus 10 (sigma 10)
  • certutil corpus 12 (sigma 10, kusto 2)
  • curl corpus 17 (sigma 14, elastic 2, splunk 1)
  • finger corpus 2 (sigma 2)
  • forfiles corpus 2 (sigma 2)
  • regsvr32 corpus 15 (sigma 15)
  • rundll32 corpus 26 (sigma 23, chronicle 2, kusto 1)
  • wget corpus 11 (sigma 8, elastic 1, splunk 1, kusto 1)
Imageends_with
  • \cmd.exe corpus 130 (sigma 130)
  • \cscript.exe corpus 73 (sigma 73)
  • \mshta.exe corpus 67 (sigma 67)
  • \powershell.exe corpus 182 (sigma 182)
  • \pwsh.exe corpus 168 (sigma 168)
  • \wscript.exe corpus 75 (sigma 75)
ParentImageends_with
  • \gup.exe corpus 2 (sigma 2)