Brett Callow, a researcher from the security outfit Emsisoft, who informed iTWire about the fact that the company was offering to decrypt these files — which nobody else has been able to given the strength of encryption used — said the company's Facebook page indicated that Fast Data was the sister company of a computer repair business called PC Link Professionals.

It was Callow who focused attention on Fast Data Recovery, having sent the company a file that had been encrypted by Dharma and obtained quotes from the company which claimed that it would be able to decrypt the file in question.

As iTWire reported on Tuesday, there is no way that such files can be decrypted unless one has access to the private key with which they have been encrypted.

Commenting on the incident, Matt Bennett, vice-president of Asia Pacific and Japan for security firm Carbon Black, said: "From what we can see, the Dharma ransomware appears to have been well written. The encryption appears to be using public/private key encryption, which means without the private key it would be almost impossible to decrypt, unless you have discovered a vulnerability in the encryption routine.

"These kinds of data recovery businesses are becoming more and more common. It’s increasingly difficult for security industry professionals to know exactly how these businesses recover data but some theories are they:

• "simply pay the ransom and keep the difference. This is most likely done after they negotiate a better rate/price;
• "when possible, use free decryption tools but still charge the customer the fee;
• "may have a way of decrypting files (possibly via contacts in the 'dark web'); and/or
• "try to decrypt and when it fails return the fee minus any 'assessment/evaluation' fees."

Bennett pointed out that the Dharma ransomware used Windows Remote Desktop Protocol for “remoting” into systems and infecting them.

"To avoid infection, businesses should ensure that the RDP is never exposed to the Internet," he said. "However, if RDP is needed, you can take the necessary precautions to minimise an attack. This includes ensuring that your Network Level Authentication is enabled, making sure that you have a username and complex password to login, ideally use Multi-Factor Authentication for RDP and making sure that your system is patched.

"Ransomware attacks are becoming all too commonplace, but there are some good cyber hygiene practices to adopt including taking regular backups of your important files, storing them on a portable USB drive, disconnecting that USB drive when you’re not actively backing up files and consider using cloud based file storage solutions that offer automated backups/rollback of your files.”