A new variant of the Zeus trojan tricks users into exposing their debit card details by displaying rogue offers when they visit Facebook, Gmail, Yahoo and Hotmail, according to researchers from security firm Trusteer.
"We've recently discovered a series of attacks being carried out by a P2P [peer-to-peer] variant of the Zeus platform against some of the Internet's leading online services and websites," Trusteer CTO Amit Klein said in a blog post Tuesday. "The attacks are targeting users of Facebook, Google Mail, Hotmail and Yahoo -- offering rebates and new security measures."
Like most financial malware, Zeus has the ability to inject malicious content into browsing sessions. This functionality is commonly used to display rogue Web forms when users visit online banking websites.
In a similar fashion, the new Zeus variant analyzed by Trusteer exploits the trust relationship between users and well-known service providers to achieve its goals, Klein said.
When victims visit Facebook, the malware displays a fake offer for getting 20 percent cash back when buying Facebook Credits with a MasterCard or Visa debit card. The users are asked to link their cards with their Facebook accounts, a process that involves exposing their card's details.
On Gmail and Yahoo, the malware offers free enrollment into a new secure payment processing system allegedly supported by 3,000 online shops and developed in partnership with Visa and MasterCard.
On Hotmail, the malware preys on fears of credit card fraud by offering users to sign up for a free debit card protection service similar to 3D Secure, that requires a password to authorize online transactions in addition to the card's security code.
"This attack is a clever example of how fraudsters are using trusted brands -- social network/email service providers and debit card providers -- to get victims to put down their guard and surrender their debit card information," Klein said. "These webinjects are well-crafted both from a visual and content perspective, making it difficult to identify them as a fraud."