A new technique called “visual spoofing” provides a way for Internet phishing scams to convincingly mimick the web sites of banks and credit card companies. The technique alters the user interface of the web browser, substituting images for parts of the browser interface that would normally help users detect the fraud.

Visual spoofing, as outlined by Don Park, uses javascript links to launch a new browser window without scrollbars, menubars, toolbars and the status bar. This coding trick is commonly used to launch pop-up ads. In visual spoofing, these GUI elements are replaced by images, allowing the site creator to substitute a fake status bar containing the URL for a legitimate site, along with an image of a “lock” indicating a secure SSL site. Park has posted a demo of the technique, which works in multiple browsers. End users have the ability to configure their browser to prevent this behavior.

Phishing attacks seek to trick account holders into divulging sensitive account information through the use of e-mails which appear to come from trusted financial institutions and retailers. Such scams have multiplied in recent months, with many taking advantage of a bug in Internet Explorer that made it easier for fraudsters to simulate the URLs of target financial institution.

Microsoft issued a patch to repair that problem on Feb. 2. Visual spoofing does not rely on the URL spoofing, relying instead on the fake images to accomplish the deceipt.