Notepad++ Updater DNS Query to Uncommon Domains

experimentalmedium

log source: windows · dns_queryauthor Swachchhanda Shrawan Poudel (Nextron Systems)date 2026-02-02

description

What this is, in brief.

Detects when the Notepad++ updater (gup.exe) makes DNS queries to domains that are not part of the known legitimate update infrastructure. This could indicate potential exploitation of the updater mechanism or suspicious network activity that warrants further investigation.

rule source (YAML)

title: Notepad++ Updater DNS Query to Uncommon Domains
id: 2074e137-1b73-4e2d-88ba-5a3407dbdce0
status: experimental
description: |
    Detects when the Notepad++ updater (gup.exe) makes DNS queries to domains that are not part of the known legitimate update infrastructure.
    This could indicate potential exploitation of the updater mechanism or suspicious network activity that warrants further investigation.
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: 2026-02-02
modified: 2026-03-16
tags:
    - attack.collection
    - attack.credential-access
    - attack.t1195.002
    - attack.initial-access
    - attack.t1557
logsource:
    category: dns_query
    product: windows
detection:
    selection:
        Image|endswith: '\gup.exe'
    filter_main_notepad_legit_domain:
        QueryName: 'notepad-plus-plus.org'
    filter_optional_sourceforge_legit_domain:
        QueryName|endswith: '.sourceforge.net'
    filter_optional_github_legit_domain:
        - QueryName|endswith: '.githubusercontent.com'
        - QueryName: 'github.com'
    filter_optional_google_storage_legit_domain:
        QueryName|endswith: '.googleapis.com'
    filter_optional_uncommon_domains:
        QueryName|endswith:
            - '.azurewebsites.net'
            - 'block.opendns.com'
            - 'gateway.zscalerthree.net'
    # Add other known legitimate domains if any
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Some legitimate network misconfigurations or proxy issues causing unexpected DNS queries.
    - Other legitimate query to official domains not listed in the filter, needing tuning.
level: medium # can be upgraded to high after tuning with known legitimate DNS queries

detects techniques (2)

ATT&CK techniques this enables or maps to.

references

External citations — patches, advisories, analysis.