iOS 5.1 Mobile Safari security flaw allows spoofing of Address Bar

Earlier this week, a security found a nasty security bug in iOS, one that affects the iOS 5.1 version of Mobile Safari. The bug, which allows a web page to spoof a different URL in the address bar was discovered and detailed by MajorSecurity.net.

"The weakness is caused due to an error within the handling of URLs when using javascript's window.open() method. This can be exploited to potentially trick users into supplying sensitive information to a malicious web site, because information displayed in the address bar can be constructed in a certain way, which may lead users to believe that they're visiting another web site than the displayed web site."

In other words, your address bar may appear to point to a banking website, which may trick you into entering your banking credentials, when in reality it's being hosted on some site where all they want is to extract your username and password.

To test out the bug, you can go to a MajorSecurity web page. Click the "Demo" button and Mobile Safari will open a new window which shows "www.apple.com" in the address bar, even though it's actually loading a page from MajorSecurity.net.

Although announced just a few days ago, MajorSecurity said that Apple was informed of the bug about three weeks ago. It's expected that Apple will release a patch quickly, probably to iOS 5.1.1.