Technical Description

A vulnerability has been identified in Microsoft Internet Explorer, which could be exploited by attackers to gain unauthorized access to arbitrary files. This flaw is due to a design error where keystroke events are cancellable via JavaScript, which could be exploited by remote attackers to trick users into uploading arbitrary files from a vulnerable system to a malicious host by convincing them to visit a specially crafted Web page and perform certain actions (e.g. write a specific text in a text field) that will cause an arbitrary file to be inadvertently uploaded.

Note : A proof of concept exploit has been released.

Affected Products

Microsoft Internet Explorer 6
Microsoft Internet Explorer 7

Solution

VUPEN Security is not aware of any vendor-supplied patch.

Disable Active Scripting in the Internet and Local intranet security zones :

- In Internet Explorer, click Internet Options on the Tools menu
- Click the Security tab
- Click Internet, and then click Custom Level
- Under Settings, in the Scripting section, under Active Scripting, click Disable, and then click OK
- Click Local intranet, and then click Custom Level
- Under Settings, in the Scripting section, under Active Scripting, click Disable, and then click OK
- If you are prompted to confirm that you want to change these settings, click Yes
- Click OK to return to Internet Explorer

Note : Disabling Active Scripting may cause some Web sites to work incorrectly.

References

http://www.vupen.com/english/advisories/2006/2161

Credits

Vulnerability reported by Charles McAuley

ChangeLog

2006-06-06 : Initial release

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