Suspicious ClickFix/FileFix Execution Pattern

Severity: high
Author: montysecurity, Swachchhanda Shrawan Poudel (Nextron Systems)
Source: upstream

Detects suspicious execution patterns where users are tricked into running malicious commands via clipboard manipulation, either through the Windows Run dialog (ClickFix) or File Explorer address bar (FileFix). Attackers leverage social engineering campaigns—such as fake CAPTCHA challenges or urgent alerts—encouraging victims to paste clipboard contents, often executing mshta.exe, powershell.exe, or similar commands to infect systems.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1204.001` User Execution: Malicious Link, `T1204.004` User Execution: Malicious Copy and Paste

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `all of selection_parent`

CommandLine|contains: '#'
ParentImage|endswith: '\explorer.exe'

Stage 2: `all of selection_cli_captcha`

or:
CommandLine|contains: account
CommandLine|contains: anti-bot
CommandLine|contains: botcheck
CommandLine|contains: captcha
CommandLine|contains: challenge
CommandLine|contains: confirmation
CommandLine|contains: fraud
CommandLine|contains: human
CommandLine|contains: identification
CommandLine|contains: identificator
CommandLine|contains: identity
CommandLine|contains: robot
CommandLine|contains: validation
CommandLine|contains: verification
CommandLine|contains: verify

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	`#` corpus 3 (sigma 3) `account` corpus 2 (sigma 2) `anti-bot` corpus 2 (sigma 2) `botcheck` corpus 2 (sigma 2) `captcha` corpus 2 (sigma 2) `challenge` corpus 2 (sigma 2) `confirmation` corpus 2 (sigma 2) `fraud` corpus 2 (sigma 2) `human` corpus 2 (sigma 2) `identification` corpus 2 (sigma 2) `identificator` corpus 2 (sigma 2) `identity` corpus 2 (sigma 2) `robot` corpus 2 (sigma 2) `validation` corpus 2 (sigma 2) `verification` corpus 2 (sigma 2) `verify` corpus 2 (sigma 2)
`ParentImage`	ends_with	`\explorer.exe` corpus 11 (sigma 11)