In 1984 computer pioneer Ken Thompson wrote one of the seminal works of computer security, Reflections on Trusting Trust [PDF]. In it he postulated putting a trojan horse inside a compiler as a means of infecting software compiled by it. 25 years later somebody has finally done just that. Researchers at anti-virus house Sophos have discovered a virus that places a backdoor into applications compiled with the Delphi language. They've identified at least 3000 separate Delphi applications that have had this backdoor compiled into them so far, including banking programs and programs used for cellphone programming.