10:36 CET, 16th March 2007 By Ina Ragragio.
There's a new spoofingvulnerability in Internet Explorer 7, one that could again be exploited by web criminals to perform phishing attacks. This time, the vulnerability is in a local resource file, "navcancl.htm", which is caused by an input validation error when generating a "Refresh the page" link.
The "navcancl.htm" file is usually loaded whenever you navigate (using IE) and then cancel the page loading, or when the page you're trying to access cannot be found. You may havenoticed that when you're trying to load a web page that's currently inaccessible, Internet Explorer 7 displays a page with the heading "Navigation to theweb page was canceled", along with a link to "Refresh the page".
The "Refresh the page" link could be manipulated by an attacker so that if you click on it, you are led to a spoofed web page.
An attack scenario would require that a user perform these steps: load the attacker's web page; click onthe link that calls "navcancl.htm"; then click on the "Refresh the page" link. While some may argue that such an attack requires too many steps, if you think about it, anyone who surfs the Internet performs the same exact steps all the time: surf, fail to access the page, refresh.
Given that the attacker constructs web pages that are appealing enough, or spoofed enough to look legitimate, and that the average user is familiar with the "Navigation canceled"event, then an attacker could likely trick a user into visiting a spoofed web page.
While no attack has yet been reported, phishers can easily exploit this vulnerability to steal banking information, account information, or usernames and passwords.
The vulnerability remains unpatched, and Microsoft has yet to respond. In the meantime, make sure that you avoid browsing untrusted web sites. In the instance that you encounter the "Refresh the page" link, avoid clicking it.
For more information on this vulnerability, you can read the whole Secunia advisory here:
Subject: New Internet Explorer 7 Spoofing Vulnerability