[+] Credits: John Page (aka hyp3rlinx)    
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/MICROSOFT-WINDOWS-CONTACT-FILE-INSUFFECIENT-UI-WARNING-WEBSITE-LINK-ARBITRARY-CODE-EXECUTION.txt
[+] ISR: ApparitionSec          


[Vendor]
www.microsoft.com


[Product]
Microsoft .CONTACT File

A file with the CONTACT file extension is a Windows Contact file. They're used in Windows 10, Windows 8, Windows 7, and Windows Vista.
This is the folder where CONTACT files are stored by default: C:\Users\[USERNAME]\Contacts\.


[Vulnerability Type]
Insufficient UI Warning Arbitrary Code Execution


[Security Issue]
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Microsoft Windows.
User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The flaw is due to the processing of ".contact" files <c:Url> node param which takes an expected website value, however if an attacker references an
executable file it will run that instead without warning instead of performing expected web navigation. This is dangerous and would be unexpected to an end user.

e.g.

<c:Url c:ElementID="xxxxxxxxxxxxxxxxxxxxxxxx"><c:Value>www.hyp3rlinx.altervista.com</c:Value> 

Executable files can live in a sub-directory so when the ".contact" website link is clicked it traverses directories towards the executable and runs.
Making matters worse is if the the files are compressed then downloaded "mark of the web" (MOTW) may potentially not work as expected with certain archive utilitys.

The ".\" chars allow directory traversal to occur in order to run the attackers supplied executable sitting unseen in the attackers directory.
This advisory is a duplicate issue that currently affects Windows .VCF files, and released for the sake of completeness as it affects Windows .contact files as well.


[Exploit/POC]
Rename any executable file extension from ".exe" to ".com" to be like a valid web domain name.
Create a directory to house the executable file
Modify the contact file website link like ---> http.\\www.<executable-name>.com
Contact website link now points at "dir .\ executable"  ---> http.\\www.<executable-name>.com
Compress the files using archive utility and place in webserver for download.


[POC Video URL]
https://vimeo.com/311759191


[Disclosure Timeline]
Reported to ZDI 2018-11-30
This exact same vulnerability exists and affects Microsoft Windows .VCF files sharing the same root cause and was publicly disclosed 2019-01-10.
https://www.zerodayinitiative.com/advisories/ZDI-19-013/
Public disclosure : January 16, 2019

   

[+] 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