Arizona-based security firm InfoArmor has been looking quite closely at the Radamant RDM v2 ramsomware variant. In its official report on the malware, InfoArmor stated that Radamant is one of the most popular commercial ransomware kits available. It has been up for sale on the black market since December 2015 and is currently offered in two versions.

Softpedia was even able to get a price on it. The source reported that the malware retailed on underground hacking forums for about $1,000 a month. Users could even pay $100 for a 48-hour test.

The Keys to Ransomware

Radamant uses a unique AES-256 key for each file it encrypts. The generated AES-256 key is then encrypted with an RSA-2048 master key, which is embedded into the header of the target file.

The master key is sent to the command-and-control (C&C) server, where it is stuffed in a MySQL database identified with the cybercriminal. When victims pay the ransom, Radamant sends them a decryption tool along with the master key necessary to unlock all files. There is even a Web-based dashboard for the cybercriminal to watch the nefarious activities unfold, which eventually led to the malware’s downfall.

InfoArmor realized that the C&C center functioned as the true brains of this particular version of ransomware. Bots did the work, but if users could fool the C&C somehow, they would beat the malware. A security researcher from Emsisoft had previously found a crypto vulnerability in RDM v1 that eventually led to the creation of a tool that would unlock the ransomed files, Softpedia reported.

How RDM v2 Is Different

But InfoArmor discovered a different method for the RDM v2 variant, which was created by cybercriminals in response to the decoding tool. The security firm found a SQL injection vulnerability in how the ransomware’s Web dashboard talks with the database in the C&C server.

It managed to exploit this flaw, and researchers were then able to modify the payment status of infected victims to paid. Once they were marked as paid in the database, the minion bots would then go off and deliver a decryption tool to the user without need for payment.

Researchers may have discovered a workaround for this Radamant ransomware, but there are still many variants of the malware without a harmless solution. The only way to avoid losing files — or paying up — is remaining alert for any possible schemes and backing up data.