Sapphire/slammer (January 2003)

400 byte UDP payload to Microsoft SQL server.
(Code red was 4 kiloybytes and TCP.)
Sapphire didn't need to stop for a response!

Doubled in size every 8 seconds 
(code red doubled every 37 minutes)

It had 90% of vulnerable hosts (about 75000) in 10 minutes.

55 million scans per second after 3 minutes.