00:00Did you know one of the most dangerous virus writers in history signed his work and still nobody can prove
00:05who he was?
00:05He called himself Dark Avenger.
00:07In the late 1980s, a virus began spreading across personal computers.
00:12Hidden inside its code was a message.
00:14This program was written in the city of Sofia.
00:17Sofia is the capital of Bulgaria.
00:19It was a signature.
00:20He wanted people to know it was his.
00:22And it was nasty.
00:23The virus spread fast.
00:24Then, after a number of infections, it quietly overwrote parts of the disk.
00:30Backups got infected too, so people didn't notice until it was too late.
00:34But his biggest move came in 1991.
00:36He released the mutation engine.
00:38It let a virus rewrite its own appearance every time it copied itself.
00:42Antivirus scanners of the time looked for fixed patterns.
00:45Now the pattern kept changing.
00:46Bulgarian researcher Veselin Bonchev studied his work, and the two reportedly communicated.
00:51Even so, Bonchev has said he never knew for sure who Dark Avenger really was.
00:56Then the message is stopped.
00:58No public arrest.
00:59No confirmed name.
01:01Just code, taunts, and a gap where a person should be.
01:04Today, Defenders still study attackers the same way.
01:07Through what they leave behind.
