Apple QuickTime Vulnerability Threatens Firefox, iTunesApple QuickTime Vulnerability Threatens Firefox, iTunes

Over the weekend, Polish security researcher Krystian Kloskowski discovered vulnerability in Apple's QuickTime media player that could allow an attacker to execute malicious code on affected systems.

"Apple QuickTime contains a stack buffer overflow vulnerability in the way QuickTime handles the RTSP Content-Type header," warns U.S. CERT in a security advisory published on Saturday. "This vulnerability may be exploited by convincing a user to connect to a specially crafted RTSP stream. Note that QuickTime is a component of Apple iTunes, therefore iTunes installations are also affected by this vulnerability."

Symantec security researcher Elia Florio reports that proof of concept exploit code has been made available and that no patch exists for the flaw at this time. He recommends that network administrators restrict outbound connections on TCP 554 using their firewalls and to urge users not to follow links to untrusted Web sites.

U.S. CERT cautions that "RTSP...may use a variety of port numbers, so blocking the protocol based on a particular port may not be sufficient."

Secunia rates the exploit "extremely critical."

The exploit has been tested on Windows Vista and Windows Pro XP 2 using QuickTime 7.2 and 7.3. Mac OS X users are also vulnerable, according to a Symantec spokesperson.

The exploit requires that the victim is duped into clicking on a Web link in an e-mail message or on a Web page that points to what appears to be a media file. In fact, the file is an XML file that makes the QuickTime player open an RTSP connection on port 554 to the malicious server hosting the exploit file. In so doing, the QuickTime player receives a malformed RTSP message that creates a buffer overflow error and allows malicious code to execute.

Florio says that the attack doesn't appear to work on Internet Explorer 6/7 and Safari 3 Beta users, but points out that Firefox users are vulnerable.

"Firefox users are more susceptible to this attack because Firefox farms off the request directly to the QuickTime Player as a separate process outside of its control," says Florio. "As a result, the current version of the exploit works perfectly against Firefox if users have chosen QuickTime as the default player for multimedia formats."

Florio also warns that this attack may work with other media file formats such as mpeg, .avi, and other MIME types that may be associated with the QuickTime player.