Windows DLL Search Order Hijack via Space in System Directory Paths

Alerts on .dll events targeting Windows system paths with an extra space, indicative of DLL search order hijacking.

FreeReviewedSigma · High · v2

Product: windows
Category: file_event
Author: frack113, Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-07-30
Updated: 2026-07-31

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1574.001DLL
Persistence
- T1574.001DLL
Priv Esc
- T1574.001DLL
Defense Evasion
- T1574.001DLL
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies Windows file events where a target DLL filename ends with .dll and starts with a system-like directory path containing an extra space (e.g., C:\Windows , C:\Program Files , or C:\Program Files (x86) ). Attackers can use this technique to influence DLL search order by placing a malicious DLL in a deceptively named folder that resembles legitimate Windows directories. Telemetry relies on file event data with the full TargetFilename value, including both the directory prefix and the DLL extension.

Reporting behind it

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Windows DLL Search Order Hijack via Space in System Directory Paths

Pivot detection · T1574.001 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-dll-search-order-hijacking-via-additional-space-in-dll-path-b6f91281

title: Windows DLL Search Order Hijack via Space in System Directory Paths
id: 4a424941-afe1-4d2e-8d1a-6456e2d4a1aa
status: test
description: This rule identifies Windows file events where a target DLL filename ends with .dll and starts with a system-like directory path containing an extra space (e.g., C:\Windows , C:\Program Files , or C:\Program Files (x86) ). Attackers can use this technique to influence DLL search order by placing a malicious DLL in a deceptively named folder that resembles legitimate Windows directories. Telemetry relies on file event data with the full TargetFilename value, including both the directory prefix and the DLL extension.
references:
  - https://twitter.com/cyb3rops/status/1552932770464292864
  - https://www.wietzebeukema.nl/blog/hijacking-dlls-in-windows
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_dll_sideloading_space_path.yml
author: frack113, Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-07-30
tags:
  - attack.persistence
  - attack.privilege-escalation
  - attack.execution
  - attack.stealth
  - attack.t1574.001
logsource:
  category: file_event
  product: windows
detection:
  selection:
    TargetFilename|startswith:
      - C:\Windows \
      - C:\Program Files \
      - C:\Program Files (x86) \
    TargetFilename|endswith: .dll
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: b6f91281-20aa-446a-b986-38a92813a18f
    type: derived

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