Mozilla Partially Vulnerable to Internet Explorer URL Spoofing Security Flaw
Thursday December 11th, 2003
koody wrote in to tell us that Mozilla is partially vulnerable to the recently announced URL spoofing security hole in Internet Explorer. The latest IE flaw allows an attacker to disguise the true domain of a URL in the browser's Address Bar, allowing a page located at evilscam.net to appear to be from microsoft.com. This exploit can be used to increase the effectiveness of the so-called 'phishing' scams that have recently been used to target customers of PayPal, eBay and several online banks.
The Address Bar URL spoofing flaw was originally reported by Sam "Zap The Dingbat" Greenhalgh, who provided details of the exploit and a demonstration. Security company Secunia issued an advisory about the vulnerability, with an update from Chris Hall reporting that the URL shown in the Status Bar while mousing over a link to a spoofed page is also affected. While Mozilla-based browsers such as the Mozilla Application Suite and Mozilla Firebird are immune to the more serious Address Bar spoofing, they appear to be vulnerable to the Status Bar variant.
The Secunia Internet Explorer Address Bar Spoofing Test page demonstrates both the full flaw in IE and the Status Bar aspect of it that affects Mozilla. The relevant Bugzilla report is bug 228176, which was filed today and already has a preliminary patch attached (please do not add unnecessary comments to the bug; the developers are already aware of its seriousness). Mozilla users are advised to not rely on the URL displayed in the Status Bar and to check the complete address of the destination page in the Location Bar upon arrival.
#29 More vulnerabilities
Friday December 12th, 2003 12:01 PM
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In your example page, the link actually does go to the Microsoft site (at least when I tried it in the Mozilla suite). Because you included the slash after microsoft.com, that ends the hostname portion and the remaining part is simply used as a path to send to that server.
Only URLs without the slash right after the "faked" hostname will "work" the way the exploiters wish. Hence, people sufficiently alert to notice the absence of the slash can possibly be clued into something being fishy, though many real site links also leave off the slash because webmasters are lazy about that sort of thing.