Cybercriminals are using the Zeus online banking malware to target companies that use cloud-based payroll services, according to researchers from security firm Trusteer.
The researchers have come across a Zeus configuration that monitors the log-in web page of a Canadian provider of human resources and payroll services called Ceridian Canada, with the purpose of stealing authentication information from its customers.
The malware steals user IDs, passwords and company numbers when users authenticate on Ceridian's clients.powerpay.ca website from infected computers and automatically takes screenshots of their answers to the site's image-based verification system.
Trusteer expects payroll services to become increasingly targeted by cybercriminals who can more easily steal large amounts of money through them than from regular online banking accounts, the company's chief technology officer, Amit Klein, said.
In general, the authentication protection measures used by payroll services lag a few years behind those used by online banking websites, Klein said.
Also, because payroll services can be accessed from anywhere, it's not always necessary for attackers to break into a corporate network to perform fraud, he said. The authentication credentials can be stolen and abused through a laptop that's regularly removed from the enterprise premises.
Once in possession of the stolen authentication credentials, the cybercriminals can add fake employees in the payroll system and transfer considerable sums of money to accounts the criminals control.
Last year, a group of cybercriminals used this method to steal $217,000 from a nonprofit organisation called the Metropolitan Entertainment & Convention Authority (MECA) based in Omaha, Nebraska.
The attackers transferred money through MECA's payroll system to the bank accounts of US residents hired through work-at-home scams, who then wired the funds out of the country, Klein said.
Unfortunately, running an antivirus program is often not enough to prevent Zeus infections, because cybercriminals who use this Trojan horse perform reconnaissance before launching their attacks in order to learn what security products their targets use. They then alter the malware to evade detection by those applications.
Products like Trusteer's Rapport are designed to secure web browsing sessions so that malware can't tamper with them and steal credentials. However, security experts have advised organisations in the past to only perform sensitive financial activities from dedicated computers that aren't used for other tasks, or to do so by booting from a Linux live CD in order to decrease the chances of malware interference.