File Download Using Notepad++ GUP Utility

Severity: high
Author: Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Detects execution of the Notepad++ updater (gup) from a process other than Notepad++ to download files.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1105` Ingress Tool Transfer

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_img`

or:
Image|endswith: '\GUP.exe'
OriginalFileName: gup.exe

Stage 2: `all of selection_cli`

CommandLine|contains: ' -unzipTo '
CommandLine|contains: http

Stage 3: `not filter`

ParentImage|endswith: '\notepad++.exe'

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
`CommandLine`	match	`-unzipTo` `http` corpus 31 (sigma 31)
`Image`	ends_with	`\GUP.exe` corpus 2 (sigma 2)
`OriginalFileName`	eq	`gup.exe`
`ParentImage`	ends_with	`\notepad++.exe`