search menu icon-carat-right cmu-wordmark

CERT Coordination Center

Microsoft Windows URI protocol handling vulnerability

Vulnerability Note VU#403150

Original Release Date: 2007-07-27 | Last Revised: 2007-11-13

Overview

Microsoft Windows fails to properly handle protocols specified in a URI, which could allow a remote, unauthenticated attacker to execute arbitrary commands on a vulnerable system.

Description

A Uniform Resource Identifier (URI) is a string of characters that can be used to identify a location, resource, or protocol. Microsoft Windows will parse a URI to determine the appropriate application that is registered to handle the protocol. More information about how Windows accomplishes this is available in Microsoft Knowledge Base article 224816. Several types of Windows applications, such as web browsers and email clients, may rely on Microsoft Windows to determine the proper application to handle a specified URI.

Internet Explorer 7 has changed how Microsoft Windows parses URIs. This has introduced a flaw that can cause Windows to incorrectly determine the appropriate handler for the protocol specified in a URI. This flaw appears to rely on having a "%" character in the URI.

Publicly available exploit code uses Mozilla Firefox as an attack vector for this vulnerability. For more information, including workarounds, please see VU#783400.

Impact

Microsoft Windows may incorrectly determine the appropriate application to handle a protocol. For example, a "safe" protocol such as mailto: may be incorrectly handled with an "unsafe" application, such as the Windows command interpreter. This can allow unexpected execution of arbitrary commands.

Solution

Apply an update
This issue is addressed in Microsoft Security Bulletin MS07-061. This update provides a newer version of Shell32.dll, which performs additional validation of URIs.

Vendor Information

403150
 
Affected   Unknown   Unaffected

Adobe

Updated:  October 11, 2007

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.

Microsoft Corporation

Notified:  July 26, 2007 Updated:  November 13, 2007

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

This issue is addressed in Microsoft Security Bulletin MS07-061. This update provides a newer version of Shell32.dll.

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

Mozilla

Updated:  October 11, 2007

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.


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 Billy Rios.

This document was written by Will Dormann.

Other Information

CVE IDs: CVE-2007-3896
Severity Metric: 18.43
Date Public: 2007-07-25
Date First Published: 2007-07-27
Date Last Updated: 2007-11-13 21:21 UTC
Document Revision: 25

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