The SSL protocol as used in certain configurations in Microsoft Windows and Microsoft Internet Explorer Mozilla Firefox Google Chrome Opera and other products encrypts data by using CBC mode with chained initialization vectors which allows man-in-the-middle attackers to obtain plaintext HTTP headers via a blockwise chosen-boundary attack (BCBA) on an HTTPS session in conjunction with JavaScript code that uses (1) the HTML5 WebSocket API (2) the Java URLConnection API or (3) the Silverlight WebClient API aka a \BEAST\ attack.