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Apple Safari automatically executes arbitrary shell commands or code

Vulnerability Note VU#999708

Original Release Date: 2006-02-21 | Last Revised: 2006-12-07

Overview

Apple Safari fails to properly determine file safety, allowing a remote unauthenticated attacker to execute arbitrary commands or code.

Description

Safari

Apple Safari is a web browser that comes with the Mac OS X operating system.

Explicit binding

Mac OS X supports a feature called explicit binding, which LaunchServices examines to determine which application is used to open a file. If explicit binding is specified for a file, this setting will override the application association for the file type. Explicit binding information is stored in the resource fork for a file.

"Safe" files

By default, Safari will automatically open "safe" file types, such as pictures, movies, and archive files, including ZIP files. If the contents of an archive file are also considered safe, then Safari will automatically open the contents after the archive is extracted.

The problem

A data file with explicit binding can allow an attacker to execute arbitrary commands or code on systems running Safari. Limited testing shows that Safari apparently fails to check for the presence of explicit binding data when determining if a file is "safe" or not.

Impact

By convincing a user to view a specially crafted HTML document (for example, a web page), an attacker may be able to execute arbitrary commands or code with the privileges of the user.
Proof of concept code is publicly available.

Solution

Install an update
Install Apple Security Update 2006-001 and Apple Security Update 2006-002, which provide updates to Safari, LaunchServices, and CoreTypes. These updates improve the method that Safari uses to determine if a file is safe.


Disable "Open 'safe' files after downloading"

Disable the option "Open 'safe' files after downloading," as specified in the Securing Your Web Browser document. This will help prevent automatic exploitation of this and other vulnerabilities.

Vendor Information

999708
 
Affected   Unknown   Unaffected

Apple Computer, Inc.

Notified:  March 02, 2006 Updated:  December 05, 2006

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Please see Apple Security Update 2006-001 and Apple Security Update 2006-002.

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


CVSS Metrics

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A

References

Credit

This vulnerability was publicly disclosed by Michael Lehn.

This document was written by Will Dormann.

Other Information

CVE IDs: CVE-2006-0848
Severity Metric: 35.44
Date Public: 2006-02-19
Date First Published: 2006-02-21
Date Last Updated: 2006-12-07 16:22 UTC
Document Revision: 37

Sponsored by the Department of Homeland Security Office of Cybersecurity and Communications.