Overview

A vulnerability has been reported in the default URI protocol handler in Apple’s Mac OS X help system. Exploitation of this vulnerability may permit a remote attacker to execute arbitrary scripts on the local system.

Description

A vulnerability has been reported in Apple’s Mac OS X runscript function of the Help.app application. Using the “help://” URI handler, a remote attacker may be able to create an HTML file that will execute local scripts on the target user’s system. If exploited conjunction with VU#210606, a remote attacker may be able to execute arbitrary code of the attacker’s choosing. Browsers or other applications supporting this help system URI handler enabled by default on Mac OS X have been reported to be vulnerable.

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Impact

A remote attacker may be able to run arbitrary files with interpretable script on a vulnerable system.

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Solution

Download updated software per Apple’s Security Update notice:

• Apple’s Software Downloads web site:

For Mac OS X 10.3.3 “Panther” and Mac OS X 10.3.3 Server

http://www.apple.com/support/downloads/securityupdate__2004-05-24_(10_3_3).html
The download file is named: “SecUpd2004-05-24Pan.dmg”
Its SHA-1 digest is: 8e505ac4e36393f44e9d1b27ac0bd9a9e9f5b6a2

For Mac OS X 10.2.8 “Jaguar” and Mac OS X 10.2.8 Server

http://www.apple.com/support/downloads/securityupdate_2004-05-24_(10_2_8).html
The download file is named: “SecUpd2004-05-24Jag.dmg”
Its SHA-1 digest is: 8c084551505fb4e7131afbf8bce14475bdc5f946

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According to a posting on Secunia, users may be able to mitigate the potential impact of this reported vulnerability by changing the protocol helpers (applications) for URI handlers which are not required, (e.g., disable “help://” execution).

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Vendor Information

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Apple Computer Inc. __ Affected

Notified: May 21, 2004 Updated: May 24, 2004

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

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

Addendum

Please see APPLE-SA-2004-05-21 Security Update 2004-05-24:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

APPLE-SA-2004-05-21 Security Update 2004-05-24

Security Update 2004-05-24 is now available and contains security
enhancements for the following:

HelpViewer: Fixes CAN-2004-0486 to ensure that HelpViewer will only
process scripts that it initiated. Credit to lixlpixel
<[email protected]> for reporting this issue. This issue has been
widely reported as a problem with the Safari web browser, but can
affect other web browsers. This update will fix the issue for Safari
and other web browsers.

Terminal: Fixes CAN-2004-0485 to improve URL processing within
Terminal. Credit to Reni Puls <[email protected]> for reporting this
issue.

================================================

Security Update 2004-05-24 may be obtained from:

• Software Update pane in System Preferences

• Apple’s Software Downloads web site:

For Mac OS X 10.3.3 “Panther” and Mac OS X 10.3.3 Server

_<http://www.apple.com/support/downloads/securityupdate__2004-05-24_&gt;_(
10_3_3).html
The download file is named: “SecUpd2004-05-24Pan.dmg”
Its SHA-1 digest is: 8e505ac4e36393f44e9d1b27ac0bd9a9e9f5b6a2

For Mac OS X 10.2.8 “Jaguar” and Mac OS X 10.2.8 Server

_<http://www.apple.com/support/downloads/securityupdate_2004-05-24_&gt;_(
10_2_8).html
The download file is named: “SecUpd2004-05-24Jag.dmg”
Its SHA-1 digest is: 8c084551505fb4e7131afbf8bce14475bdc5f946

Information will also be posted to the Apple Product Security web
site:
_<http://www.apple.com/support/security/security_updates.html&gt;_

This message is signed with Apple’s Product Security PGP key, and
details are available at:
_<http://www.apple.com/support/security/security_pgp.html&gt;_

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If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23578798 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://docs.info.apple.com/article.html?artnum=61798&gt;
• <http://secunia.com/advisories/11622/&gt;
• <http://www.securitytracker.com/alerts/2004/May/1010167.html&gt;
• <http://www.apple.com/support/security/security_updates.html&gt;

Acknowledgements

Thanks to Kang for reporting this vulnerability.

This document was written by Jason A Rafail and is based on information from Secunia.com and SecurityTracker.com.

Other Information

CVE IDs:	CVE-2004-0486
Severity Metric:	19.89 Date Public: