Despite McColo's takedown, observers say that major senders of spam and malware are returning -- and may be stronger than ever.
Just weeks after the shutdown of major spam host McColo led to a sharp drop in unwanted e-mails, spammers and malicious botnets are showing signs of returning.
McColo's takedown by its ISPs also hit botnets like Srizbi hard, since they had been hosted on McColo -- and their designs made them especially vulnerable to the loss of their host, according to Derek Manky, lead threat researcher for Fortinet.
"Srizbi, for example, was using hard-coded command-and-control servers hosted at McColo, and when these were taken offline, the botnet was rendered useless," Manky told
InternetNews.com in an e-mail.
However, Srizbi, Rustock, Asprox and other botnets are beginning to come back to life, if shakily, experts said. And they may have new allies in the form of cash-strapped ISPs.
