Notepad++ Updater DNS Query to Uncommon Domains

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

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.

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1195.002` Supply Chain Compromise: Compromise Software Supply Chain
Credential Access	`T1557` Adversary-in-the-Middle
Collection	`T1557` Adversary-in-the-Middle

Event coverage

Provider	Event	Title
Sysmon	Event ID 22	DNSEvent (DNS query)

Rule body 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

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: `selection`

selection:
    Image|endswith: '\gup.exe'

Stage 2: `not filter_main_notepad_legit_domain`

filter_main_notepad_legit_domain:
    QueryName: 'notepad-plus-plus.org'

Stage 3: `not filter_optional_*`

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'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`QueryName`	eq	`notepad-plus-plus.org`
`QueryName`	ends_with	`.azurewebsites.net`
`QueryName`	ends_with	`.githubusercontent.com`
`QueryName`	ends_with	`.googleapis.com`
`QueryName`	ends_with	`.sourceforge.net`
`QueryName`	ends_with	`block.opendns.com`
`QueryName`	ends_with	`gateway.zscalerthree.net`
`QueryName`	eq	`github.com`

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.

Field	Kind	Values
`Image`	ends_with	`\gup.exe` corpus 5 (sigma 5)

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Notepad++ Updater DNS Query to Uncommon Domains

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_notepad_legit_domain`

Stage 3: `not filter_optional_*`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Notepad++ Updater DNS Query to Uncommon Domains

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_main_notepad_legit_domain

Stage 3: not filter_optional_*

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_notepad_legit_domain`

Stage 3: `not filter_optional_*`