Unlike with previously revealed vulnerabilities, computers can be infected simply by visiting one of the Web sites or viewing an infected image in an e-mail through the preview pane in older versions of Microsoft Outlook, even if users did not click on anything or open any files.

...Dean Turner, a senior manager at anti-virus firm Symantec Corp. of Cupertino, Calif., said the company has seen the vulnerability exploited to install software that intercepts personal and financial information when users of infected computers enter the data at certain banking or e-commerce sites.