wimgapi.dll
There are executables that allowwimgapi.dll to be DLL hijacked.Expected Locations
The filewimgapi.dll is normally found in the following paths:
%SYSTEM32%%SYSWOW64%%PROGRAMFILES%\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools\arm64\DISM
Vulnerable Executables
DLL Sideloading (3 EXEs)
By copying (and optionally renaming) any of the following vulnerable applications to a user-writeable folder, alongside a malicious
wimgapi.dll, arbitrary code can be executed through it.
Phantom DLL Hijacking (1 EXE)
By copying a malicious
wimgapi.dll to a specific location, the following vulnerable applications will execute the malicious DLL's code upon normal execution.
Detection
Below a sample Sigma rule that will find processes that loadedwimgapi.dll located in a folder that is not one of the expected locations (see above).
title: Possible DLL Hijacking of wimgapi.dll
id: 1854941b-9395-48a3-4833-5b9ff8418066
status: experimental
description: Detects possible DLL hijacking of wimgapi.dll by looking for suspicious image loads, loading this DLL from unexpected locations.
references:
- https://hijacklibs.net/entries/microsoft/built-in/wimgapi.html
author: "Wietze Beukema"
date: 2021-02-27
tags:
- attack.defense_evasion
- attack.T1574.001
- attack.T1574.001
logsource:
product: windows
category: image_load
detection:
selection:
ImageLoaded: '*\wimgapi.dll'
filter:
ImageLoaded:
- 'c:\windows\system32\\*'
- 'c:\windows\syswow64\\*'
- 'c:\program files\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools\arm64\DISM\\*'
- 'c:\program files (x86)\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools\arm64\DISM\\*'
condition: selection and not filter
falsepositives:
- False positives are likely. This rule is more suitable for hunting than for generating detections.title: Possible preparation for wimgapi.dll DLL Hijacking
id: 1854942b-9395-48a3-4833-5b9ff8418066
status: experimental
description: Detects possible DLL hijacking of wimgapi.dll by looking for suspicious file writes of this DLL, to unexpected locations.
references:
- https://hijacklibs.net/entries/microsoft/built-in/wimgapi.html
author: "Wietze Beukema"
date: 2021-02-27
tags:
- attack.defense_evasion
- attack.T1574.001
- attack.T1574.001
logsource:
product: windows
category: file_event
detection:
selection:
TargetFileName: '*\wimgapi.dll'
filter:
TargetFileName:
- 'c:\windows\system32\\*'
- 'c:\windows\syswow64\\*'
- 'c:\program files\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools\arm64\DISM\\*'
- 'c:\program files (x86)\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools\arm64\DISM\\*'
- 'c:\windows\winsxs\*'
- 'c:\$windows.~bt\*'
- 'c:\windows\softwaredistribution\*'
condition: selection and not filter
falsepositives:
- False positives are likely. This rule is more suitable for hunting than for generating detections.title: Possibly malicious versions of wimgapi.dll
id: 1854943b-9395-48a3-4833-5b9ff8418066
status: experimental
description: Detects possible DLL hijacking of wimgapi.dll by looking for versions not meeting the known signature data.
references:
- https://hijacklibs.net/entries/microsoft/built-in/wimgapi.html
author: "Wietze Beukema"
date: 2021-02-27
tags:
- attack.defense_evasion
- attack.T1574.001
- attack.T1574.001
logsource:
product: windows
category: image_load
detection:
selection:
ImageLoaded: '*\wimgapi.dll'
filter:
ImageLoaded:
- Signed: 'true'
- SignatureStatus: 'signed'
- Signature|contains:
- 'CN=Microsoft Windows, O=Microsoft Corporation, L=Redmond, S=Washington, C=US'
condition: selection and not filter
falsepositives:
- False positives are likely. This rule is more suitable for hunting than for generating detections.Note that this rule is also included in the Detection Content Feeds that comprise all DLL Hijacking entries part of HijackLibs.
FAQs
Why should I care about this?
DLL Hijacking enables the execution of malicious code through a signed and/or trusted executable. Defensive measures such as AV and EDR solutions may not pick up on this activity out of the box, and allow-list applications such as AppLocker may not block the execution of the untrusted code. There are numerous examples of threat actors that have been observed to leaverage DLL Hijacking to achieve their objectives. As such, this project wants to encourage you to monitor for unusual activity involvingwimgapi.dll.
How do I abuse this vulnerability?
As a red teamer, you will have to compile your own version ofwimgapi.dll. There are various guides on how this can be achieved.