June 30th, 2008

Exploit code released for unpatched IE 7 vulnerability

Posted by Ryan Naraine @ 11:59 am

Categories: Arbitrary Code Execution, Botnets, Browsers, Data theft, Exploit code, Malware, Microsoft, Responsible disclosure, Spyware and Adware, Vulnerability research, Zero-day attacks

Tags: Attacker, Vulnerability, Microsoft Internet Explorer 7, Domain, Exploit Code, Microsoft Internet Explorer, Web Browsers, Internet, Ryan Naraine

Another day, another gaping hole affecting fully patched versions of Microsoft’s Internet Explorer browser.

According to a warning from US-CERT, proof-of-concept exploit code has been published for a new zero-day bug that can be used for a variety of malicious attacks against Windows users running IE 6, IE 7, and IE 8 beta 1.

The code, published here by ’sirdarckat’,  shows how the vulnerability can be exploited to hijack an iFrame in a legitimate site and capture a target’s keystrokes. This occurs because  Internet Explorer fails to properly restrict access to a document’s frames, allowing an attacker to modify the contents of frames in a different domain.

[ SEE: Zero-day flaw haunts Internet Explorer ]

This screenshot (of a proof-of-concept created by researcher Aviv Raff) shows the Google home page in a frame hijacked from Microsoft’s Windows Update site.  The security implications are rather frightening:

Can you imagine if someone spoofs this page with their own rigged Microsoft Update download page?

From the US-CERT advisory:

Microsoft Internet Explorer fails to properly restrict access to a document’s frames. This can allow an attacker to replace the contents of a web page’s frame with arbitrary content. Internet Explorer still appears to enforce the cross-domain security model, which limits the actions that a malicious frame can take with the parent document. For example, a frame that exists in a different domain should not be able to access the parent document’s cookies or HTML content, or other domain-specific DOM components. However, components that are not tied to a specific domain, such as the onmousedown event. By monitoring this particular event, an IFRAME can capture keystrokes from the parent document. Other actions may be possible.

…By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message), an attacker may be able to access non-domain-specific elements from a web page that exists in a different domain. For example, the attacker may be able to capture keystrokes while a user is interacting with a web page in a different domain.

[ ALSO SEE: Internet Explorer ‘feature’ causing drive-by malware attacks ]