Vulnerability Note VU#751808

Apple QuickTime remote command execution vulnerability

Overview

Apple QuickTime contains a vulnerability that may allow an attacker to pass arbitrary commands to other applications.

I. Description

Apple QuickTime is a media player that is available for Microsoft Windows and Apple OS X. Apple QuickTime includes browser plugins for Internet Explorer, Safari, and Netscape-compatible browsers.

QuickTime includes the ability for developers to control how QuickTime movies are launched, what controls are displayed to the user, and other actions. To specify these parameters, developers can create QuickTime link (.qtl) files. QuickTime link files can be embedded in web pages and launched automatically when a user visits a website.

The qtnext parameter can be used in QuickTime link files to specify the url of a multimedia file to load and play. The multimedia file may be hosted on a web page or stored locally.

Apple QuickTime incorrectly determines the command line used to launch the default web browser on Microsoft Windows systems. Rather than using the ShellExecute method, QuickTime determines the default handler for .HTM files and then crafts its own command line for the registered application. Any protective flags in the registered file handler are stripped out by QuickTime.

Current proof-of-concept code targets systems where Mozilla Firefox is the default handler for .HTM files. Other applications are also affected by this vulnerability, although the impact may vary based on what command line parameters the application accepts.

II. Impact

By convincing a user to open a specially crafted QuickTime file, a remote, unauthenticated attacker may be able execute arbitrary commands on a vulnerable system.

III. Solution

Apple has released an update to address this issue. Mozilla has released Firefox 2.0.0.7 which reduces the impact of this vulnerability.

Restrict access to QuickTime Movies

Until updates can be applied, the following workarounds may mitigate this vulnerability. Some web sites may allow anonymous users to upload QuickTime movies that exploit this vulnerability.

Workarounds for users

• Mozilla has released Firefox 2.0.0.7 which may prevent exploitation of this vulnerability by removing Firefox's ability to run arbitrary scripts which are provided by command line arguments. Users are encouraged to upgrade as soon as possible.
  
• Using the NoScript Firefox extension to whitelist web sites that can run scripts and access installed plugins will mitigate this vulnerability. See the NoScript FAQ for more information.
  
• Running Firefox with a limited user account may prevent an attacker from accessing or overwriting files that the limited user account does not have write access to.
  
  Workarounds for administrators
  
• Proxy servers or intrusion prevention systems may be able to filter QuickTime files and partially mitigate this vulnerability. Note that this workaround is not likely to mitigate or stop all attack vectors.

Systems Affected

Vendor	Status	Date Updated
Apple Computer, Inc.	Vulnerable	4-Oct-2007
Mozilla	Vulnerable	20-Sep-2007

References

http://docs.info.apple.com/article.html?artnum=306560
http://www.gnucitizen.org/blog/0day-quicktime-pwns-firefox
http://www.mozilla.org/security/announce/2007/mfsa2007-28.html
http://blog.mozilla.com/security/2007/09/18/firefox-2.0.0.7-now-available/
http://secunia.com/advisories/26881/
http://docs.info.apple.com/article.html?artnum=305149
http://developer.apple.com/quicktime/quicktimeintro/tools/embed2.html
http://noscript.net/features#contentblocking
http://noscript.net
http://msdn2.microsoft.com/en-us/library/ms647732.aspx
http://support.microsoft.com/kb/224816

Credit

This vulnerability was disclosed by pdp on the GNUCITIZEN website.

This document was written by Ryan Giobbi and Will Dormann.

Other Information

Date Public	09/12/2007
Date First Published	09/13/2007 05:00:24 PM
Date Last Updated	10/04/2007
CERT Advisory
CVE Name	CVE-2007-4673
Metric	35.11
Document Revision	51