search menu icon-carat-right cmu-wordmark

CERT Coordination Center

CGI.pm vulnerable to Cross-site Scripting

Vulnerability Note VU#246409

Original Release Date: 2003-10-07 | Last Revised: 2004-02-23

Overview

A vulnerability in the Common Gateway Interface (CGI) Perl module may allow an attacker to mount a cross-site scripting attack against a vulnerable system.

Description

The Common Gateway Interface, or CGI, is a standard for external gateway programs to interface with information servers such as HTTP servers. The standard Perl distribution and many vendor's repackaged Perl systems include a CGI library known as CGI.pm. This module offers a set of functions for creating fill-out forms, among other things.

Some versions of the CGI.pm module contain a vulnerability in handling of the action in the start_form() and start_multipart_form() functions. When the action for the form is not specified, a default based on the user-supplied URL is used. Because the value of this expression is not sanitized by the module before processing and contains user-supplied data or data received from untrustworthy sources, a remote attacker may be able to inject HTML or malicious script. A user of the vulnerable site or web application may then be tricked into interpreting the HTML or executing the script in a situation where they normally might not.

Impact

The victim will be presented with information that the vulnerable site did not wish their visitors to be subjected to. This could be used to "sniff" sensitive data from within the web page, including passwords, credit card numbers, and any arbitrary information the user inputs. This exploitation vector is commonly referred to as a cross-site scripting attack.

Solution

Apply a patch from the vendor

Versions 2.94 and later of the CGI.pm module contain a fix for this vulnerability. Please see the vendor section of this document for further details.

Vendor Information

246409
 

CVSS Metrics

Group Score Vector
Base
Temporal
Environmental

References

Acknowledgements

Thanks to Obscure for reporting this vulnerability.

This document was written by Chad R Dougherty with feedback from Sean Levy.

Other Information

CVE IDs: CVE-2003-0615
Severity Metric: 15.00
Date Public: 2003-07-19
Date First Published: 2003-10-07
Date Last Updated: 2004-02-23 22:11 UTC
Document Revision: 12

Sponsored by CISA.