1200KM / sigma-rule
Suspicious Explorer Process with Whitespace Padding - ClickFix/FileFix — Sigma Rule
Sigma rule 3ae9974a-eb09-4044-8e70-8980a50c12c8. Suspicious Explorer Process with Whitespace Padding - ClickFix/FileFix — Sigma Rule. Detects process creation with suspicious whitespace padding followed by a '#' character, which may indicate ClickFix or FileFix techniques used to conceal malicious commands from visual inspection. ClickFix and FileFix are social engineering attack techniques where adversaries distribute phishing documents or malicious links that deceive users into opening the Windows Run dialog box or File Explorer search bar. The victims are then instructed to paste commands from their clipboard, which contain extensive whitespace padding using various Unicode space characters to push the actual malicious command far to the right, effectively hiding it from immediate view.
Rule metadata and linked tags
Author: Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: high. Source dates: 2025-11-04 / 2025-11-26.
{
"category": "process_creation",
"product": "windows"
}Pinned original Sigma rule · Detection Rule License 1.1
Source SHA-256: 3068737e7dafcd6278b24d47f99ae18c78b5f857bae82b2a7fe981bc7c71cdcb
Detection logic
Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.
title: Suspicious Explorer Process with Whitespace Padding - ClickFix/FileFix
id: 3ae9974a-eb09-4044-8e70-8980a50c12c8
related:
- id: 8f2a5c3d-9e4b-4a7c-8d1f-2e5a6b9c3d7e
type: similar
- id: 7a1b4c5e-8f3d-4b9a-7c2e-1f4a5b8c6d9e
type: similar
status: experimental
description: |
Detects process creation with suspicious whitespace padding followed by a '#' character, which may indicate ClickFix or FileFix techniques used to conceal malicious commands from visual inspection.
ClickFix and FileFix are social engineering attack techniques where adversaries distribute phishing documents or malicious links that deceive users into opening the Windows Run dialog box or File Explorer search bar.
The victims are then instructed to paste commands from their clipboard, which contain extensive whitespace padding using various Unicode space characters to push the actual malicious command far to the right, effectively hiding it from immediate view.
references:
- https://expel.com/blog/cache-smuggling-when-a-picture-isnt-a-thousand-words/
- https://mrd0x.com/filefix-clickfix-alternative/
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-11-04
modified: 2025-11-26
tags:
- attack.execution
- attack.stealth
- attack.t1204.004
- attack.t1027.010
logsource:
category: process_creation
product: windows
detection:
selection_explorer:
ParentImage|endswith: '\explorer.exe'
CommandLine|contains: '#'
selection_space_variation:
CommandLine|contains:
- ' ' # En Quad (U+2000)
- ' ' # Em Quad (U+2001)
- ' ' # En Space (U+2002)
- ' ' # Em Space (U+2003)
- ' ' # Three-Per-Em Space (U+2004)
- ' ' # Four-Per-Em Space (U+2005)
- ' ' # Six-Per-Em Space (U+2006)
- ' ' # Figure Space (U+2007)
- ' ' # Punctuation Space (U+2008)
- ' ' # Thin Space (U+2009)
- ' ' # Hair Space (U+200A)
- ' ' # No-Break Space (U+00A0)
- ' ' # Normal space (0x20)
condition: all of selection_*
falsepositives:
- Unknown
level: high
False positives
- Unknown
Source references
Connected ecosystem references
Exact source-tagged techniques
Telemetry review
Read the original logsource above, then inspect the linked detection workspaces for technique-level sensor context. No per-rule telemetry equivalence is inferred.
Pinned research references. No browser attack runner, live simulation result or validated detector is asserted. Source mappings and validation limits are preserved. ATT&CK / Atomic provenance · Detection provenance.