Vulnerability Note VU#820427

Microsoft Hyperlink Object Library buffer overflow

Overview

A buffer overflow exists in the Microsoft Windows system library used when handling hyperlinks. All currently supported versions of Microsoft Windows are affected.

I. Description

An unchecked buffer in the Microsoft Object Library is vulnerable to attack when malformed hyperlinks are handled. Such handling occurs most often when a user clicks on a hyperlink in a browser or in HTML-rendered email.

The Object Library is a dynamic application interface library used by Windows programs to manage hyperlink objects. Hyperlink objects are any COM objects (including ActiveX) that implement the IHlink interface.

II. Impact

An attacker could execute arbitrary code of their choosing on the system running the vulnerable version of Windows. Upon successful exploitation, the malicious code would be executed with the privileges of the user being attacked.

III. Solution

Apply a patch from the vendor

Microsoft has published Microsoft Security Bulletin MS05-015 in response to this issue. Users are encouraged to review this bulletin and apply the patches it refers to.

Workarounds

As noted in Microsoft Security Bulletin MS05-015:

Read e-mail messages in plain text format if you are using Outlook 2002 or a later version, or Outlook Express 6 SP1 or a later version, to help protect yourself from the HTML e-mail attack vector.

Note that an email-borne attack vector requires a click event on a hyperlink to occur.

Systems Affected

Vendor	Status	Date Updated
Microsoft Corporation	Vulnerable	8-Feb-2005

References

http://www.us-cert.gov/cas/techalerts/TA05-039A.html
http://www.microsoft.com/technet/security/bulletin/ms05-015.mspx
http://msdn.microsoft.com/workshop/misc/hlink/overview/overview.asp
http://msdn.microsoft.com/workshop/misc/hlink/reference/ifaces/ihlink/ihlink.asp

Credit

Microsoft has acknowledged Anna Hollingzworth as the discoverer of this vulnerability.

This document was written by Jeffrey S Havrilla.

Other Information

Date Public	02/08/2005
Date First Published	02/08/2005 05:34:23 PM
Date Last Updated	02/08/2005
CERT Advisory
CVE Name	CAN-2005-0057
US-CERT Technical Alerts
Metric	55.28
Document Revision	10

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