Rufus 3.17.1846 DLL Hijacking

`Hi all,  
  
I would like to disclose a vulnerability that I just found today.  
  
Details below:  
  
Vulnerable Software and Version:  
  
1. Rufus 3.17.1846 executable  
2. Rufus 3.17.1846 portable executable  
  
Vulnerable software download link:  
https://rufus.ie/en/  
  
https://github.com/pbatard/rufus/releases/tag/v3.17  
  
Date discovered and reported:  
25 Feb 2022  
  
Description:  
Both Rufus 3.17.1846 executable AND portable executable are suffering from DLL  
Hijacking by placing x86 MSASN1.dll or VERSION.dll in the same directory as  
the executables, which could cause arbitrary code execution and privilege  
escalation.  
  
Taking MSASN1.dll as an example, craft a malicious x86 DLL with an entry  
point with DllMain and place in the same directory, once double click the  
executable, an x86 admin shell could be obtained as the executable requires  
admin right to run by design.  
  
Attack vector:  
Taking MSASN1.dll as an example PoC code of dll can be found in my  
repository  
  
Attack steps:  
  
1.  
  
Craft and drop a malicious DLL named as "MSASN1.dll" with entry point  
DllMain [image: image]  
<https://user-images.githubusercontent.com/21979646/155570972-1ca622d7-f75e-42ba-b9e5-45eace8fd8d3.png>  
2.  
  
Double click the executable "Rufus", administrator privilege is required  
to run  
3.  
  
Malicious DLL has been called and an admin shell can be obtained as  
PoC [image:  
image]  
<https://user-images.githubusercontent.com/21979646/155571105-aabc503a-47e9-4489-b6f8-df1aad548b70.png>  
  
  
This issue has been submitted to github as well and is acknowledged by the  
owner,  
https://github.com/pbatard/rufus/issues/1877  
  
Thanks and regards,  
James Tsz Ko Yeung  
  
  
`