U.S. federal law enforcement and computer security agencies recently released a rare security alert, citing that a North Korean hacking group is actively targeting media, aerospace, financial, and critical infrastructure sectors in the United States and around the world. The hackers are believed to have used a botnet creation malware called DeltaCharlie to launch DDoS attacks.

http://www.corero.com/blog/825-ddos-botnets-north-korea-and-the-threat-of-cyber-war.html