Two-Thirds Of All Phishing Attacks Generated By A Single Criminal Group, Researchers Say

Like convenience stores and fast-food restaurants, phishing is no longer a mom-and-pop operation, according to a study released today.

A single crime syndicate dubbed "Avalanche" was responsible for some 66 percent of the phishing traffic generated in the second half of 2009, according to a report (PDF) published by the Anti-Phishing Working Group (APWG).

"Avalanche" is the name given to the world's most prolific phishing gang and to the infrastructure it uses to host phishing sites, according to APWG. "This criminal enterprise perfected a system for deploying mass-produced phishing sites, and for distributing malware that gives the gang additional capabilities for theft," the study says.

Avalanche successfully targeted some 40 banks and online service providers, as well as vulnerable or nonresponsive domain name registrars and registries, in the second half of 2009, according to APWG.

Avalanche could be a successor to the "Rock Phish" criminal operation, which became notorious between 2006 and 2008, APWG says.

"The Rock was the first to bring significant scale and automation to phishing," the report states. "The Rock registered domain names regularly and in large numbers, used fast-flux hosting to support its phishing Web sites and extend their uptimes, and usually placed about six discrete phishing attacks on each domain name."

Avalanche was first seen in December 2008, and was responsible for 24 percent of the phishing attacks recorded in the first half of 2009, the study says. "Avalanche uses the Rock's techniques but improves upon them, introducing greater volume and sophistication," it says.

To speed its spread of attacks, Avalanche runs on a botnet and uses fast-flux hosting that makes mitigation efforts more difficult, APWG says. "There is no ISP or hosting provider who has control of the hosting and can take the phishing pages down, and the domain name itself must be suspended by the domain registrar or registry," the report notes.

An Avalanche attack campaign utilizes a set of domain names that appear almost identical to each other (such as 11f1iili.com, 11t1jtiil.com, 11t1kt1il.com, and 11t1kt1pl.com), the report says. These domain name sets are therefore distinctive and recognizable to those who are looking for them.

"When setting up an attack, Avalanche registered domains at one to three registrars or resellers," APWG reports. "The gang often targets a small number of other registrars, testing to see if those registrars notice. If one registrar starts to quickly suspend the domains or implements other security procedures, the criminals simply move on to other vulnerable registrars. One unresponsive or vulnerable registrar can become a gateway for ongoing abuse."

Although Avalanche snowballed in the second half of 2009, its impact has melted significantly this year, the report says.

"Because they were so damaging, prevalent, and recognizable, Avalanche attacks received concentrated attention from the response community," APWG says. "As a result, Avalanche attacks had a much shorter average uptime than non-Avalanche phishing attacks, and community efforts partially neutralized the advantage of the fast-flux hosting. Despite this, the attacks were obviously profitable, and they continued in volume.

"In mid-November 2009, members of the security community affected a temporary shut-down of the Avalanche botnet infrastructure," the report continues. "This lasted about a week before the criminals behind the attacks re-established their network. After this event, Avalanche’s activities changed significantly."

Avalanche domain registrations hit a high in December 2009, but by then Avalanche was hosting fewer and fewer attacks overall, the study says. "By March 2010, Avalanche was hosting only one phishing attack on each domain it registered, and attacks dwindled to just 59 in the month of April 2010."

While it appears that Avalanche might have hit the skids, the report leaves the door open for another, similar attack in the future.

"The old Rock Phish operation became quiescent in the summer of 2008, only to be re-born a few months later as the even worse Avalanche," the report states. "As of this writing, Avalanche has dwindled to a shadow of its former self. Will Avalanche fade for good, or will it too be reborn as something new?"

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