Vulnerability Note VU#808921

eBay contains a cross-site scripting vulnerability

Overview

The eBay web site contains a cross-site scripting vulnerability.

I. Description

eBay is a popular auction web site. When an eBay user posts an auction, eBay allows SCRIPT tags to be included in the auction description. This creates a cross-site scripting vulnerability in the eBay website. More information about cross-site scripting is available in CERT Advisory CA-2000-02.

II. Impact

An attacker may be able to obtain sensitive data from the eBay web site. As of the publication of this document, attackers are using this vulnerability to redirect auction viewers to phishing sites and to modify the eBay auction page to steal credentials. A wide range of impacts may be possible, including disclosure of passwords, credit card numbers, or other personal information. Likewise, information stored in cookies could be stolen or corrupted. An attacker could also exploit web browser vulnerabilities that require scripting support.

III. Solution

We are currently unaware of a practical solution to this problem, however the following workarounds may help mitigate the vulnerability:

Disable scripting

Disable scripting in your web browser, as specified in the Securing Your Web Browser document and the Malicious Web Scripts FAQ. This can also be accomplished by adding "ebay.com" to the Restricted Sites zone in Internet Explorer. Users of Mozilla-based browsers can use Configurable Security Policies (CAPS) to disable scripting for the "ebay.com" web site.

Validate web site addresses

When interacting with web sites, pay close attention to the web site address displayed by the browser. Especially when providing login information, make sure the web browser is displaying the proper URL, as described in the eBay Spoof Email Tutorial and US-CERT Cyber Security Tip ST04-014.

Validate web site certificates

Web sites may require sensitive information such as passwords or credit card information. In these cases, make sure the web site is using an encrypted (HTTPS) connection. Validate the web site certificate, as described in US-CERT Cyber Security Tip ST05-010.

Systems Affected

Vendor	Status	Date Updated
eBay	Vulnerable	2-Apr-2006

References

http://www.cert.org/advisories/CA-2000-02.html
http://www.cert.org/tech_tips/malicious_code_FAQ.html
http://www.us-cert.gov/cas/tips/ST04-014.html
http://www.us-cert.gov/cas/tips/ST05-010.html
http://pages.ebay.com/education/spooftutorial/spoof_3.html
http://pages.ebay.com/help/policies/listing-javascript.html
http://pages.ebay.com/securitycenter/
http://news.com.com/2100-7349_3-6056687.html
http://news.com.com/2100-1017-224622.html

Credit

Thanks to Dan Plakosh of CERT/CC for reporting this vulnerability.

This document was written by Will Dormann.

Other Information

Date Public	04/19/99
Date First Published	04/03/2006 02:04:06 PM
Date Last Updated	05/02/2006
CERT Advisory	CA-2000-02
CVE Name
US-CERT Technical Alerts
Metric	9.58
Document Revision	18

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Produced 2006 by US-CERT, a government organization
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