December 14, 2012, 11:58 AM — Several malicious Android apps designed to steal mobile transaction authentication numbers (mTANs) sent by banks to their customers over SMS (Short Message Service) were found on Google Play by researchers from antivirus vendor Kaspersky Lab.
The apps were created by a gang that uses a variant of the Carberp banking malware to target the customers of several Russian banks, Denis Maslennikov, a senior malware analyst at Kaspersky, said Friday in a blog post.
Many banks use mTANs as a security mechanism to prevent cybercriminals from transferring money from compromised online banking accounts. When a transaction is initiated from an online banking account, the bank sends an unique code called an mTAN via SMS to the account owner's phone number. The account owner has to input that code back into the online banking website in order for the transaction to be authorized.
In order to defeat this type of defense, cybercriminals created malicious mobile apps that automatically hide SMS messages received from numbers associated with the targeted banks and silently upload the messages back to their servers. Victims are tricked into downloading and installing these apps on their phones via rogue messages displayed when visiting their bank's website from an infected computer.
SMS stealing apps have previously been used together with the Zeus and SpyEye banking Trojan programs and are known as Zeus-in-the-Mobile (ZitMo) and SpyEye-in-the-Mobile (SpitMo) components. However, this is the first time a rogue mobile component designed specifically for the Carberp malware has been found, Maslennikov said.
Unlike Zeus and SpyEye, the Carberp Trojan program is primarily used to target online banking customers from Russia and other Russian-speaking countries like Ukraine, Belarus or Kazakhstan.
According to a report in July from antivirus vendor ESET, Russian authorities arrested the people behind the three largest Carberp operations. However, the malware continues to be used by other gangs and is being sold on the underground market for prices between US$5,000 and $40,000, depending on the version and its features.
"This is the first time we've seen mobile malicious components from a Carberp gang," Aleksandr Matrosov, senior malware researcher at antivirus vendor ESET, said Friday via email. "Mobile components are used only by one Carberp group, but we can't disclose more details at the present."