East European botnet targets Russian banks

Cybercriminals based in Russia and Eastern Europe typically avoid targets in their home countries, but a botnet called Tinba is proving to be an exception, according to a new report from the Dell SecureWorks’ Counter Threat Unit.

The Tinba Banking Trojan, also known as Tiny Banker because of its small file size, is targeting the biggest banks and payment service providers in Russia, said Brett Stone-Gross, senior security researcher at Dell SecureWorks.

It is believed to be controlled by a group operating out of Eastern Europe.

A total of 34.5 percent of the victims of the botnet were located in Russia, and another 22 percent of victims were in Poland.

“Traditionally what you see with these banking Trojans, the majority of infections are in the US or Western Europe,” he said.

But in this case, the US was in 12th place, with just 1.6 percent of the victims.

This is very unusual, said Stone-Gross. Typically, malware writers bend over backwards to ensure they’re not hitting local targets, including checking computer languages and keyboard layouts.

“The criminals have always gone where the money is, and at the least risk of being prosecuted for their crimes,” he said.

Russian authorities may be less willing to collaborate with Western law enforcement authorities and less likely to arrest cybercriminals who target other banks, he explained.

By comparison, when criminals target local institutions, reaction can be swift.

For example, the Carberp banking Trojan that reportedly stole $250 million from Ukraininan and Russian banks in 2013 was taken down by local authorities and its leaders arrested.

“They feel much safer if they don’t target their own,” he said.

Tinba is different, Stone-Gross said, in that it’s a kit sold on an affiliate basis through online forums and partners.

“We see, as a result of that, different criminals groups are running their own Tinba botnets,” he said.

It is possible and even likely, he added, that a Ukrainian group is running this particular Tinba botnet.

“The Ukraine and Russia are not on the best of speaking terms right now, and law enforcement might not collaborate with each other,” he said.

Stone-Gross declined to provide the names of the Russian banks and payment systems targeted by Tinba, other than to say that they included the largest such institutions in the country.

The current version of Tinba, Tinba 2.0, was first released a year ago and is now responsible for tens of thousands of active infections.

It is small, just 25 kilobytes, about a tenth the size of other banking Trojans. But it still packs in a fair bit of functionality.

According to the researchers, it comes with a domain generation algorithm, and RSA signature verification to confirm that it is communicating with the real command and control server, not a security researcher’s sinkhole. It also comes with a variety of features that allow it to steal account credentials and one-time passwords.