Apple QuickTime RTSP buffer overflow

Categoria: Alertas

terça, 27 novembro 2007 12:09

Sistemas Operativos Implicados:	Windows XP/NT/2K/Me/98/95
Aplicações Implicadas:	Indefinido

Apple QuickTime contém uma vulnerabilidade stack buffer overflow que poderá permitir que um atacante remoto não autenticado execute código arbitrário ou cause uma condição de negação de serviço. O Real Time Streaming Protocol (RTSP) é um protocolo utilizado para streaming de sistemas media. O Apple QuickTime Streaming Server e QuickTime player ambos têm como suporte o RTSP.

Overview

Apple QuickTime contains a stack buffer overflow vulnerability that may allow a remote, unauthenticated attacker to execute arbitrary code or cause a denial of service condition.

I. Description

Real Time Streaming Protocol (RTSP) is a protocol that is used by streaming media systems. The Apple QuickTime Streaming Server and QuickTime player both support for RTSP.

Apple QuickTime contains a stack buffer overflow vulnerability in the way QuickTime handles the RTSP Content-Type header. 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. We are aware of publicly available exploit code for this vulnerability.

Limited testing has shown that QuickTime versions 4.0 through 7.3 are vulnerable on all supported Mac and Windows platforms.

II. Impact

By convincing a user to connect to a specially crafted RTSP stream, a remote, unauthenticated attacker may be able to execute arbitrary code on a vulnerable system. An attacker can use various types of web page content, including a QuickTime Media Link file, to cause a user to load an RTSP stream.

III. Solution

We are currently unaware of a practical solution to this problem. Please consider the following workarounds. Note that these workarounds will not address the vulnerability, but they may help block certain attack vectors for the vulnerability.

Block the rtsp:// protocol

Blocking the RTSP protocol with proxy or firewall rules may help mitigate this vulnerability. Note that RTSP (default 554/tcp and 6970-6999/udp) may use a variety of port numbers, so blocking the protocol based on a particular port may not be sufficient.

Disable the QuickTime ActiveX controls in Internet Explorer

The QuickTime ActiveX controls can be disabled in Internet Explorer by setting the kill bit for the following CLSIDs:

{02BF25D5-8C17-4B23-BC80-D3488ABDDC6B}
{4063BE15-3B08-470D-A0D5-B37161CFFD69}

More information about how to set the kill bit is available in Microsoft Support Document 240797. Alternatively, the following text can be saved as a .REG file and imported to set the kill bit for these controls:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINESOFTWAREMicrosoftInternet ExplorerActiveX Compatibility{02BF25D5-8C17-4B23-BC80-D3488ABDDC6B}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINESOFTWAREMicrosoftInternet ExplorerActiveX Compatibility{4063BE15-3B08-470D-A0D5-B37161CFFD69}]
"Compatibility Flags"=dword:00000400

Disable the QuickTime plug-in for Mozilla-based browsers

Users of Mozilla-based browsers, such as Firefox can disable the QuickTime plugin, as specified in the PluginDoc article Uninstalling Plugins.

Disable file association for QuickTime files

Disable the file association for QuickTime file types to help prevent windows applications from using Apple QuickTime to open QuickTime files. This can be accomplished by deleting the following registry keys:

HKEY_CLASSES_ROOTQuickTime.*

This will remove the association for approximately 32 file types that are configured to open with the QuickTime Player software.

Disable JavaScript

For instructions on how to disable JavaScript, please refer to the Securing Your Web Browser document. This can help prevent some attack techniques that use the QuickTime plug-in or ActiveX control.

Do not access QuickTime files from untrusted sources

Attackers may host malicious QuickTime files on web sites. In order to convince users to visit their sites, those attackers often use a variety of techniques to create misleading links including URL encoding, IP address variations, long URLs, and intentional misspellings. Do not click on unsolicited links received in email, instant messages, web forums, or internet relay chat (IRC) channels. Type URLs directly into the browser to avoid these misleading links. While these are generally good security practices, following these behaviors will not prevent exploitation of this vulnerability in all cases, particularly if a trusted site has been compromised or allows cross-site scripting.

Systems Affected

Vendor	Status	Date Updated
Apple Computer, Inc.	Vulnerable	25-Nov-2007

References

http://www.cert.org/tech_tips/securing_browser/
http://www.beskerming.com/security/2007/11/25/74/QuickTime_-_Remote_hacker_automatic_control
http://www.milw0rm.com/exploits/4648
http://tools.ietf.org/html/rfc2326
http://tools.ietf.org/html/rfc2326#section-12.16
http://www.apple.com/quicktime/technologies/streaming/
http://www.gnucitizen.org/blog/backdooring-mp3-files/
http://developer.apple.com/quicktime/icefloe/dispatch028.html
http://www.apple.com/quicktime/resources/qt/us/proxy/

Credit

This vulnerability was publicly disclosed by Krystian Kloskowski.

This document was written by Ryan Giobbi and Will Dormann.