An Android Trojan program originally designed to steal mobile banking credentials from Russian users was recently retrofitted with ransomware functionality and has started infecting users in the U.S., using photos of its victims to intimidate them into paying a fictitious FBI fine.
Known as Svpeng, the Trojan program was first detected almost a year ago targeting customers of Russia's three largest banks, according to security researchers from antivirus vendor Kaspersky Lab. Its initial variants detected when users opened the targeted mobile banking apps and displayed a fake login screen to capture log-in credentials. A similar technique was used to collect credit card details when users opened Google Play.
"At the beginning of 2014, we detected a new modification of Svpeng with ransomware capabilities," said Roman Unuchek, a senior malware analyst at Kaspersky Lab, in a blog post Wednesday. "When instructed by its server, the malware attempted to block the user's phone and display a message demanding payment of a US$500 'fee' for alleged criminal activity."
That ransomware function was further improved and at the beginning of June a new variant of Svpeng was identified on mobile phones outside of Russia. Ninety-one percent of users affected by the new version were based in the U.S., but the malware also infected devices in the U.K., Switzerland, Germany, India and Russia, Unuchek said.
Upon installation, the new Svpeng modification claims to perform a device scan and displays a fake notification from the FBI warning the user that the device was used to visit porn websites and has downloaded "prohibited content."
The malware then blocks access to the device's usual functions and asks the owner to pay a fine of US$200 through a payment service called MoneyPak. The rogue warning includes a photo of the phone owner taken automatically with the device's camera -- an obvious attempt at intimidation.
"When it comes to ransomware Trojans, the new modification of Svpeng stands out for its wholly new implementation of standard features -- it completely blocks the mobile device, even making it impossible to invoke the menu to switch off or reload the device," Unuchek said. "The victim can turn off the device by pressing the on/off button for a few seconds, but the Trojan immediately starts working as soon as the device is switched on again."
The malware's code includes references to a Java class called Cryptor, suggesting that Svpeng might start encrypting files in the future, a technique increasingly used by ransomware threats for both Windows and Android.
An Android Trojan program called Android/Simplocker.A, found recently by security researchers from ESET, encrypts files stored on an infected phone's SD memory card and asks for money to restore them.
The new Svpeng variant doesn't steal mobile banking credentials, but there are indications that this feature is being planned. The malware checks to see whether mobile banking apps from several U.S. financial institutions including American Express, Citibank, Chase Bank, Wells Fargo, Bank of America, TD Bank and BB&T are installed on the affected devices and uploads the scan results to its command-and-control server.
"The cybercriminals are probably just gathering statistics about the use of these apps on infected devices," Unuchek said. "Considering that Svpeng is, first and foremost, a banking Trojan, we can expect to see attacks on the clients of these banks who use mobile apps to manage their accounts."