Security researchers at DefCon demonstrated how an enterprising hacker could "tap" into a supposedly secure data stream to lift sensitive information.

There are major problems in the way browsers interact with Secure Sockets Layer (SSL) certificates, which is a common technology used on banking, e-commerce and other sites handling sensitive data.

Browser makers and the companies that sell SSL certificates are working on a fix. Microsoft Corp., whose Internet Explorer browser is the world's most popular, said it was investigating the issue. Mozilla Corp., which makes the No. 2 Firefox browser, said most of the problems being addressed were fixed in the latest version of its browser, and that the rest will be fixed in an update coming this week. VeriSign Inc., one of the biggest SSL certificate companies, maintains that its certificates aren't vulnerable.