IE 7, released last week, allows a Web site to display a pop-up that can contain a spoofed Web address, security monitoring company Secunia said Wednesday. An attacker could exploit this weakness to trick people into believing they are on a trusted Web site when in fact they are viewing a malicious page, Secunia said in an alert.

"This makes it possible to only display a part of the address bar, which may trick users into performing certain unintended actions," Secunia said. The company has created a demonstration that shows a Microsoft Web address in the pop up window, but displays content from Secunia.

The problem lies in the way Web addresses are displayed in the IE 7 address bar, a Microsoft representative said in an e-mailed statement. An attacker could exploit the issue by tricking a user to click on a specially formatted link, the representative said.

The pop-up will block the left part of the Web address, Microsoft said. "Clicking in the browser window or in the address bar and scrolling within it will display the full URL, however," the company said. In case of the Secunia example, the true Secunia URL is revealed.