A British security researcher has figured out a way to <A HREF="http://www.eweek.com/article2/0,1759,2016606,00.asp?kc=EWRSS03119TX1K0000594">manipulate legitimate features in Adobe PDF files</A> to open back doors for computer attacks. David Kierznowski, a penetration testing expert specializing in Web application testing, has released proof-of-concept code and rigged PDF files to demonstrate how the Adobe Reader program could be used to launch attacks without any user action.