Study Finds Spammers' Weak Spot

Instead of trying to stop the spray of spam as it comes out of the firehose, maybe we should be looking to shut it off at the hydrant, some university researchers are suggesting this week.

In a report issued yesterday, computer scientists at the University of California at San Diego said they have found "striking differences" between the infrastructure used to distribute spam and the infrastructure used to collect responses from its victims. The net result: Most spam responses are collected by a single, individual Web server.

Ninety-four percent of the scams advertised via embedded links are hosted on individual Web servers, according to a paper that will be presented at the USENIX Security 2007 conference in Boston tomorrow.

"A given spam campaign may use thousands of mail relay agents to deliver its millions of messages, but it may use only a single server to handle requests from recipients who respond. A single takedown of a scam server -- or a spammer redirect -- can curtail the earning potential of an entire spam campaign," the report says.

Using new Internet monitoring approaches developed at UCSD, the computer scientists studied a spam feed over the course of a week. They analyzed spam-advertised Web servers hosting online scams that either offer merchandise and services or use malicious means to defraud users. The researchers followed the URLs embedded in spam back to the hosting servers, probed the servers, and analyzed the Web pages advertised in the spam.

"Our findings suggest that the current scam infrastructure is particularly vulnerable to common blocking techniques, such as blacklisting," says Geoff Voelker, a computer science and engineering professor at the UCSD Jacobs School.

The research was enabled by UCSD's "spamscatter" approach, which allowed the computer scientists to study more than a million spam messages from a live feed. Spamscatter allows researchers to mine emails, identify URLs in real time, and follow these links through any redirection mechanisms and onto the Web page of the destination server.

"Spamscatter provides a mechanism for studying global Internet behavior from a single vantage point," says Voelker.

— Tim Wilson, Site Editor, Dark Reading