Network World - A Web hack that can endanger online banking transactions is ranked the No. 1 new Web hacking technique for 2010 in a top 10 list selected by a panel of experts and open voting. Called the Padding Oracle Crypto Attack, the hack takes advantage of how Microsoft 's Web framework ASP.NET protects AES encryption cookies. FROM THE SECURITY WORLD: Quirky moments at Black Hat DC 2011 If encryption data in the cookie has been changed, the way ASP.NET handles it results in the application leaking some information about how to decrypt the traffic. With enough repeated changes and leaked information, the hacker can deduce which possible bytes can be eliminated from the encryption key.