About yesterday's Twitter attack

http://ping.fm/qX3Pe

In the distributed denial of service (DDOS) attack on the sites, computers that have been compromised by viruses or other malware are instructed by the attacker's computer to visit the specific Web sites all at the same time and repeatedly. The barrage of connection requests overwhelms the target sites, making it so that legitimate Web traffic can't get through.

Such coordinated attacks require the efforts of tens of thousands or more of hijacked computers, which together form a botnet. Spammers send e-mails with malicious attachments or URLs to millions of people to create botnets. Criminals also can lease existing botnets for specific campaigns for as little as 5 cents to 10 cents per bot.