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IBM Net.Data db2www CGI interpreter fails to properly validate requested macro filenames

Vulnerability Note VU#197318

Original Release Date: 2004-03-08 | Last Revised: 2004-03-19

Overview

IBM Net.Data fails to properly validate user input passed to the db2www CGI interpreter, which could allow an attacker to mount a cross-site scripting attack against a vulnerable system.

Description

IBM Net.Data is a scripting language used to create web applications. Net.Data macros are supplied to a CGI interpreter (db2www) that generates HTML output. The db2www CGI interpreter fails to properly validate requested macro filenames before returning at least one type of error message (DTWP001E). It is possible to use a cross-site scripting technique to inject malicious script (JavaScript, VBScript, etc.) or HTML into the error message by using a specially crafted macro filename.

Impact

A remote attacker could access sensitive information related to the vulnerable web page (cookies, form values, URI data). The attacker could also attempt to mislead the user into providing sensitive information such as login credentials.

Solution

The CERT/CC is currently unaware of a practical solution to this problem.

Disable Scripting

To help defend against cross-site scripting attacks from the client's perspective, disable scripting in your web browser and HTML-enabled email client. Instructions for disabling scripting can be found in the CERT/CC Malicious Web Scripts FAQ.

Vendor Information

197318
 
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IBM Affected

Notified:  March 08, 2004 Updated: March 15, 2004

Status

Affected

Vendor Statement

IBM acknowledges that this vulnerability exists in the Net.Data product and has already responded to Secunia with the workaround listed below.

For more information see the Secunia advisory.

Workaround:

To block a Net.Data application from being exploited by the vulnerability, the administrator of the Net.Data application has to utilize the DTW_DEFAULT_ERROR_MESSAGE feature, available on all platforms.

Example: In the Net.Data configuration file 'db2www.ini', insert an entry such as

DTW_DEFAULT_ERROR_MESSAGE <PRE>This Web Site is experiencing problems. Check back later. </PRE>

With such an entry, Net.Data will not return the "DTWP001E" error message, thus blocking any security exposure.

Furthermore, Net.Data on zOS and iServer provide a very similar feature, DTW_DEFAULT_MACRO (see Net.Data documentation). Please note that the DTW_DEFAULT_ERROR_MESSAGE feature and the DTW_DEFAULT_MACRO feature are generally recommended to have a web site react in a predictable manner on any kind of problem.

Vendor Information

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

Addendum

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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References

Acknowledgements

Thanks to Secunia for the information contained in their security advisory.

This document was written by Damon Morda.

Other Information

CVE IDs: None
Severity Metric: 1.58
Date Public: 2004-01-26
Date First Published: 2004-03-08
Date Last Updated: 2004-03-19 16:53 UTC
Document Revision: 22

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