Vulnerability Note VU#998369

Apple Web Kit-based browsers may allow remote access to local filesystem contents

Overview

Web browsers based on AppleWebKit may allow remote web sites to reference content on the local filesystem. This may allow an attacker to execute script within the security context of the local machine.

I. Description

Web browsers that allow remote web sites to reference content that resides on the local filesystem may be vulnerable to cross-domain security violations. In a typical attack scenario, an attacker must first place content in a known or predictable location on a computer. If a web browser allows a remote web site to reference that content, this may allow attacker-supplied script to run within the security context of the local machine.

Web browsers based on AppleWebKit, such as Safari, fail to restrict web sites from accessing content on the local filesystem. OmniWeb, which is based on Apple WebCore, also contains the same vulnerability. Current proof-of-concept exploit code uses the XMLHttpRequest object to read files from the local filesystem.

II. Impact

A remote, unauthenticated attacker may be able to execute script within the security context of the local machine. Script that executes within this context may be able to perform privileged actions, such as reading files from the local filesystem. These actions would not be possible by using script that executes within the security context of the remote web site.

III. Solution

Upgrade or patch

Please see the Systems Affected section of this document for update availability.

Workarounds

Users who are unable to upgrade to a fixed version of the software are encouraged to disable JavaScript in their browsers.

Systems Affected

Vendor	Status	Date Updated
Apple Computer Inc.	Vulnerable	21-Apr-2005
KDE Desktop Environment Project	Not Vulnerable	11-May-2005
OmniGroup	Vulnerable	6-Jul-2005

References

http://remahl.se/david/vuln/001/
http://docs.info.apple.com/article.html?artnum=301327
http://www.osvdb.org/15637
http://xforce.iss.net/xforce/xfdb/20124
http://secunia.com/advisories/14974
http://www.securityfocus.com/bid/13202
http://packetstormsecurity.org/0504-advisories/apple_webkit_filedisclosure.txt
http://www.omnigroup.com/applications/omniweb/releasenotes/

Credit

Thanks to David Remahl for reporting this vulnerability.

This document was written by Will Dormann.

Other Information

Date Public	04/16/2005
Date First Published	07/06/2005 02:39:28 PM
Date Last Updated	07/06/2005
CERT Advisory
CVE Name	CAN-2005-0976
Metric	4.78
Document Revision	13

If you have feedback, comments, or additional information about this vulnerability, please send us email.