LinkedIn Attack Spreads Zeus Financial Malware

On Monday, online attackers unleashed a flood of emails targeting the LinkedIn social network. According to Cisco, at the attack's peak on Monday, the related emails accounted for nearly 25% of all spam globally.

The emails arrive with an innocuous-looking -- but fake -- request to become a LinkedIn contact of the sender. Clicking on the provided link launches a website where a screen asks the viewer to wait for four seconds, before redirecting to Google.

Cisco said that "during those four seconds, the victim's PC is infected with the Zeus data theft malware by a drive-by download."

Zeus -- aka Zbot -- is a sophisticated financial malware toolkit that helps criminals automatically create online attacks, supported by botnets, aimed at stealing people's finance-related credentials, such as bank account login information. In other words, rather than directly attacking bank systems, attackers simply try to fool bank users.

"Targeting social network users for distributing financial malware is a smart move for the criminals," said Mickey Boodaei, CEO of security firm Trusteer, in a statement. "These attacks are much more likely to succeed than phishing attacks on banks. Once Zeus [is] installed on the user's computer then the criminals get access not only to login information but also to real-time transactions and other sensitive information."

The masterminds behind Zeus also keep the software updated, no doubt to keep their own customers happy. Recent upgrades have added -- sometimes for an extra price -- back-door connection modules to compromised PCs, as well as anti-piracy features aimed at competitors' malware toolkits.

Unfortunately, with its latest upgrade, Zeus now appears able to target smartphones too. "What's dangerous in this approach is that the same malware controls two communication channels -- the PC and the mobile device -- and as a result can launch extremely effective attacks against banks and organizations that rely on these two channels for authentication and transactions," says Boodaei.

For example, an attacker might infect both a person's PC and smartphone, steal money, and then reroute any security-check phone calls from the bank. "So when the bank detects a suspicious transaction and calls the customer for confirmation, the criminals can pick up the phone on the other side and do that on behalf of the customer," he said.