A new encryptor – Jaff ransomware – could be heading your way via email. Jaff ransomware is being distributed by the individuals responsible for distributing the Dridex banking Trojan and Locky ransomware. The gang has also previously used Bart ransomware to encrypt files in an attempt to extort money from businesses.
In contrast to Locky and many other ransomware variants, the individuals behind Jaff ransomware are seeking a huge ransom payment to unlock files, suggesting the new variant will be used to target businesses rather than individuals. The ransom demand per infected machine is 1.79 Bitcoin – around $3,300. The WannaCry ransomware variant only required a payment of $300 per infected machine.
The distributors have used exploit kits in the past to spread infections, although spam email is used for the latest campaign. Whether that will remain the only distribution mechanism remains to be seen. Millions of spam email messages have already sent via the Necurs botnet, according to Proofpoint researchers who identified the new encryptor.
The emails have a PDF file attachment rather than a Word document. Those PDF files contain embedded Word documents with macros that will download the malicious payload. This method of distribution has been seen with Locky ransomware in recent weeks.
The change in file attachment is believed to be an attempt to get users to open the attachments. There has been a lot of publicity about malicious Word documents attached to emails from unknown senders. The change could see more end users open the attachments and infect their devices.
Opening the PDF file will present the user with a screen advising them that the contents of the document are protected. They are prompted to ‘enable editing’ by ignoring the security warning and enabling macros. Enabling macros will result in infection. Jaff ransomware will then search for and encrypt a wide range of file types including images and multimedia files, databases, office documents and backups.
There is no known decryptor for Jaff ransomware. Recovery will depend on a viable backup existing that has not been encrypted by the ransomware. The alternatives are to pay the sizable ransom payment or permanently lose files.
To protect against the threat, an advanced spam filtering solution should be implemented to prevent the emails from reaching end users’ inboxes. As a failsafe, employees should be warned about the threat of ransomware and instructed not to open any file attachments from unknown senders. They should also be alerted to the threat from PDF files containing embedded word documents.