Vulnerability Note VU#795720

Microsoft Internet Explorer does not properly handle cached HTTPS contents

Overview

Microsoft Internet Explorer fails to properly validate cached HTTPS contents, allowing an attacker to obtain information or spoof information on a secure web site.

I. Description

The HTTPS protocol is used to provide authentication, encryption, integrity, and non-repudiation services to web applications. Microsoft Internet Explorer (IE) does not properly validate cached HTTPS content. An attacker could exploit this vulnerability by creating a web site with the same host name as the legitimate HTTPS protected web site. When the attacker's web site is viewed, the contents are cached. If the attacker redirects the victim's browser to the legitimate web site, the attacker's cached contents are then displayed within the context of that web site. The cached content could include script code, images, or other locally cached items.

II. Impact

An attacker may be able to spoof information on a secure web site. Using script, an attacker may be able to retrieve cookies or other information from a secure web session.

III. Solution

Apply a patch

Apply the patch referenced in MS04-038.

Do not save encrypted pages to disk

To prevent this vulnerability from being exploited, change the IE settings to not save encrypted contents to disk. To make this change, follow these steps (provided by MS04-038):

In Internet Explorer, click Internet Options on the Tools menu.
Click the Advanced tab.
Under Settings, scroll to Security.
Under Settings, in the Security section, click Do not save encrypted pages to disk.
Click OK two times to return to Internet Explorer.

Systems Affected

Vendor	Status	Date Updated
Microsoft Corporation	Vulnerable	15-Oct-2004

References

http://www.acrossecurity.com/aspr/ASPR-2004-10-13-1-PUB.txt
http://www.microsoft.com/technet/security/bulletin/MS04-038.mspx
http://securitytracker.com/alerts/2004/Oct/1011642.html
http://xforce.iss.net/xforce/xfdb/17654

Credit

Thanks to Microsoft for reporting this vulnerability. Microsoft credits Mitja Kolsek from ACROS Security for reporting the vulnerability.

This document was written by Will Dormann.

Other Information

Date Public	10/12/2004
Date First Published	10/19/2004 02:20:03 PM
Date Last Updated	10/21/2004
CERT Advisory
CVE-ID(s)	CAN-2004-0845
NVD-ID(s)	CAN-2004-0845
US-CERT Technical Alerts
Metric	9.72
Document Revision	8

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