Code Red was a computer worm designed to exploit major flaws in Microsoft’s Internet Information Services web server. In July 2001, Code Red reportedly
attacked over 350,000 web servers, defacing web pages with messages like “Hacked by Chinese.” This widespread attack was possible because worms self-replicate and spread themselves to other machines in the same network. The cost of recovery and damages from this attack was estimated to be $2.75 billion.