A new Android mobile Trojan called SimpLocker has emerged from a rather shady Russian forum, encrypting files for ransom. AVAST detects the Trojan as Android:Simplocker, avast! Mobile Security and avast! Mobile Premium users can breathe a sigh of relief; we protect from it!

The Trojan was discovered on an underground Russian forum by security researchers at ESET. The Trojan is disguised as an app suitable for adults only. Once downloaded, the Trojan scans the device’s SD card for images, documents and videos, encrypting them using Advanced Encryption Standard (AES). The Trojan then displays a message in Russian, warning the victim that their phone has been locked, and accusing the victim of having viewed and downloaded child pornography. The Trojan demands a $21 ransom be paid in Ukrainian currency within 24 hours, claiming it will delete all the files it has encrypted if it does not receive the ransom. Nikolaos Chrysaidos, Android Malware Analyst at AVAST, found that the malware will not delete any of the encrypted files, because it doesn't have the functionality to do so. Targets cannot escape the message unless they deposit the ransom at a payment kiosk using MoneXy. If the ransom is paid the malware waits for a command from its command and control server (C&C) to decrypt the files.

What can we learn from this?

Although this Trojan only targets a specific region and is not available on the Google Play Store, it should not be taken lightly. This is just the beginning of mobile malware, and is thought to be a proof-of-concept. Mobile ransomware especially is predicted to become more and more popular. Once malware writers have more practice, see that they can get easy money from methods like this, they will become very greedy and sneaky.

We can only speculate about methods they will come up with to eventually get their malicious apps onto official markets, such as Google Play, or even take more advantage of alternative outlets such as mobile browsers and email attachments. It is therefore imperative that people download antivirus protection for their smartphones and tablets. Mobile devices contain massive amounts of valuable data and are therefore a major target.

Ransomware can be an effective method for criminals to exploit vulnerable mobile users, many of which don’t back up their data. Just as in ransomware targeting PCs, this makes the threat of losing sentimental data, such as photos of family and friends or official documents, immense.

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