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Microsoft Internet Explorer allows arbitrary local file reading via "showHelp()" function

Vulnerability Note VU#400577

Original Release Date: 2003-02-06 | Last Revised: 2003-02-13


A vulnerability in Microsoft Internet Explorer (IE) allows remote attackers to read arbitrary files on a vulnerable system.


A vulnerability in the showHelp Method contained within IE may allow a remote attacker to read arbitrary files. For further details, please see the following documents:

Although a patch is available, it is important to note that it *disables* the showHelp method, but does not "fix" it. In order to restore the functionality showHelp provides, you must install the latest version of HTML Help. Additionally, the latest version of HTML Help contains some limitations. Quoting from Microsoft Security Bulletin MS03-004:
    • Only supported protocols can be used with showHelp to open a web page or help (chm) file.
    • The shortcut function supported by HTML Help will be disabled when the help file is opened with showHelp This change will not affect the shortcut function if the user opens the same CHM file manually by double-clicking on it, or by invoking an application on the local system that uses the HTMLHELP( ) API.
Microsoft recommends using to obtain the latest version of HTML Help.


A remote attacker may be able to read arbitrary files on a vulnerable system, which may allow them to gain access to sensitive information such as user credentials. In the worst case, a remote attacker may be able to execute programs with certain parameters leading to a total system compromise if IE is running as administrator.


Apply a patch. More information about patches can be found in MS03-004.

Vendor Information


Microsoft Corporation Affected

Updated:  February 06, 2003



Vendor Statement


Vendor Information

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


The CERT/CC has no additional comments at this time.

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

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This vulnerability was discovered by Andreas Sandblad. The CERT/CC thanks Andreas for helping us to understand this vulnerability.

This document was written by Ian A Finlay.

Other Information

CVE IDs: CVE-2003-1328
Severity Metric: 28.69
Date Public: 2003-02-05
Date First Published: 2003-02-06
Date Last Updated: 2003-02-13 19:31 UTC
Document Revision: 21

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