Full Disclosure mailing list archives
Re: Defense in depth -- the Microsoft way (part 64): Windows Defender loads and exeutes arbitrary DLLs
From: "Stefan Kanthak" <stefan.kanthak () nexgo de>
Date: Sat, 28 Mar 2020 00:48:54 +0100
"Paul Szabo" <paul.szabo () sydney edu au> wrote:
Does this mean that unprivileged users can defeat WindowsDefender, even when that is "enforced" by managers? Surely that would be a vulnerability! I am not knowledgeable about Windows management, but the pages https://docs.microsoft.com/en-us/configmgr/protect/deploy-use/endpoint-protection
https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-antivirus/configuration-management-reference-windows-defender-antivirus
suggest that enforcement of WindowsDefender is a supported feature.
Yes, partially: this vulnerability allows unprivileged users a) to bypass "on-demand" scans of files downloaded from the internet or other computers (which are initiated by the attachment manager), b) to load an arbitrary DLL whenever a program calls the attachment manager or the IOfficeAntiVirus interface to initiate an "on-demand" scan; "realtime" scans initiated via the file system filter driver of the anti-malware platform are NOT affected. regards Stefan
On 2020-03-27 15:27, Stefan Kanthak wrote:in September 2017, Microsoft relocated many executable files of Windows Defender from the directory "%ProgramFiles%\Windows Defender\" to "%ProgramData%\Microsoft\Windows Defender\platform\<version>\" ... Of special interest here is the IOfficeAntiVirus implementation ... This interface is called by the attachment manager ... "Thanks" to the environment variable specified in the registered path "%ProgramData%\Microsoft\Windows Defender\platform\<version>\MpOav.dll", an unprivileged user/attacker can provide an arbitrary DLL which is then loaded and executed ... ... Vendor statement: The MSRC assigned case 57439 to the above report, and replied with the following statements: | After investigation, our engineers have determine this this behavior | is by-design and does not constitute as a vulnerability as reported. ...
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Current thread:
- Defense in depth -- the Microsoft way (part 64): Windows Defender loads and exeutes arbitrary DLLs Stefan Kanthak (Mar 27)
- Re: Defense in depth -- the Microsoft way (part 64): Windows Defender loads and exeutes arbitrary DLLs Paul Szabo (Mar 31)
- Re: Defense in depth -- the Microsoft way (part 64): Windows Defender loads and exeutes arbitrary DLLs Stefan Kanthak (Mar 31)
- Re: Defense in depth -- the Microsoft way (part 64): Windows Defender loads and exeutes arbitrary DLLs Paul Szabo (Mar 31)