To be fair, legal liability and economic realities sometimes make it hard for ISPs to respond to the threat in a meaningful way. But in light of the surging malware problem, their frequent inaction looks more and more like complicity.
Although some ISPs are more active than others in policing their networks, absentee abuse departments and a lack of enforcement seems to be the rule. The Register spent several weeks calling ISPs large and small, including Comcast, OpimumOnline, Verizon, Earthlink and Road Runner. Many didn't bother to return our repeated calls. And all declined our requests for an interview with a member of their security team to discuss what steps they take to ensure their networks are not used as a launch pad for computer attacks.
The Worst of the Lot
The criticisms go well beyond abuse handlers who don't answer their email. According to this list from antispam organization Spamhaus, Deutsche Telekom users accounted for an estimated 2.2 percent of all compromised systems on the internet. The dubious distinction ranks the German ISP as the 11th most bot-infested provider, just narrowly edging out Verizon, which accounted for an estimated 1.97 percent. (Spamhaus Figures, which change frequently, were current as of time of writing).
Other European and US-based providers with unfavorable ratings include Telecom Italia, Comcast, Arcor, France Telecom and Road Runner, which together provided net access for an estimated 4.2 percent of the world's infected hosts.
Take a gander at other lists that track spam origins and you'll find many of the same names. According to the Trend Micro's Network reputation ranking, subscribers from Verizon, Telecom Italia, France Telecom, BT, Road Runner, Telefonica Data Espana and Tiscoli, AT&T, Cableinet Telewest Broadband and Comcast are some of the most prodigious senders of spam.
Because almost all spam is generated by bot-infected PCs, the rankings are a strong indication that those networks are home to a large number of zombies under the control of criminal gangs. Comcast and Road Runner declined to comment. Verizon turned down requests for an interview with a security engineer, but a spokeswoman said officials are aware of the rankings and are working to put new measures in place by the end of the year to curb the spam flowing out of its network. "We are concerned about it," the spokeswoman, Bobbi Hensen, said. "We don't like spam. We are aggressively working on that."