In the wake of the posting in online forums of stolen account and password information for thousands of Hotmail, Gmail and Yahoo e-mail accounts, there's evidence of yet more abuse that entails attackers exploiting that information to hack into compromised accounts over the last few days to send spam aimed at stealing credit cards.
According to Patrik Runald, senior manager security research at Websense, the security firm has noticed about a 40% surge in spam related to Yahoo, Gmail and Hotmail accounts in the past few days, with some of the spam being a phishing scam related to a fake Chinese electronics shopping site. Attackers have been taking advantage of the exposed account information for Hotmail, Gmail and Yahoo to break into the victim's e-mail accounts and send out deceptive messages to the victim's contacts to promote the scam.
Websense has noticed this phishing scam since the beginning of the year.
"We have talked with people who received these messages," Runald says. "It's coming from people they know and it correlates with the Gmail, Yahoo and Hotmail account compromises."
The goal of the fake Chinese electronics wholesaler scam, of course, is to get the victim's credit card. But the attackers in this Chinese electronics wholesaler phishing scam are probably not the individuals — or group of individuals — that have posted the thousands of compromised Gmail, Hotmail and Yahoo account data online during the past week.
Researchers say they are puzzling over the reason the stolen Webmail account data was posted and questioning the explanation most frequently heard that it's due to a large-scale phishing scheme.
"Given the number of disparate webmail services involved, it's more likely the result of malware on those victims' computers," says ScanSafe researcher Mary Landesman, who adds there appear to be about 20,000 compromised Gmail, Yahoo, Hotmail and now also EarthLink and AOL accounts for which passwords and names have been posted online this past week.
Password-stealing Trojans are on the rise, and if victims don't manage to get rid of them, the Trojans will steal any new password and send it off to attackers again, she points out.
Runald at Websense points out that the storing of a large cache of user credentials such as passwords for e-mail accounts is a commonplace occurrence in the cybercrime underworld. What's different this week is that someone decided to advertise some of these stolen credentials publicly online, producing an "A" and "B" list of names for stolen Hotmail names and passwords, implying the rest of the alphabet is being held somewhere.
"It’s a teaser," says Runald, noting the effect, based on the public uproar when Microsoft and other service providers verify the account data is stolen, shows that someone is holding authentic stolen data, probably for sale. The idea is to be able to charge a certain amount for it by showing it’s for real.
Although phishing is being offered as the way that cybercriminals amassed this stolen e-mail data, Runald, like Landesman, says Websense researchers are not entirely at ease with that as an explanation. "But no one really knows," he says, adding even just anger by someone who had the information could be a cause.