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New Jaff Ransomware Variant Emerges

Although it dominated headlines over the past couple of weeks, WannaCry wasn’t the only ransomware family running rampant. Another active threat was Jaff, a ransomware family that emerged just days before the WannaCry outbreak.

Although it dominated headlines over the past couple of weeks, WannaCry wasn’t the only ransomware family running rampant. Another active threat was Jaff, a ransomware family that emerged just days before the WannaCry outbreak.

Right from the start, Jaff stood out because it was being distributed by the Necurs botnet and was using a similar ransom page design as Locky. Thus, it didn’t take long for security researchers to associate the new threat with the actors behind Locky and Dridex, who also launched the Bart ransomware last year.

The ransomware was appending the .jaff extension to the encrypted files and demanding a huge ransom, at around 2 Bitcoin. The infection vector was .PDF files sent as attachments in spam emails.

A newly observed Jaff variant continues to use Necurs and PDF files for infection, but moved away from the .jaff extension and the Locky-like ransom note, Brad Duncan, Palo Alto Networks threat intelligence analyst and handler at the SANS Internet Storm Center, says.

The ransomware now appends the .wlu extension to the encrypted files and uses a ransom note featuring green fonts on a dark background. The security researcher also noticed that the ransomware authors ask for a 0.35630347 Bitcoin ransom now.

First observed on Tuesday, May 23, the spam emails distributing the new Jaff variant use a fake invoice theme. These messages feature a PDF attachment that contains an embedded Word document with malicious macros designed to infect the machine with rasomware.

“The Word macros generate an initial URL to download an encoded Jaff binary, then we see one other URL for post-infection callback from an infected host. The initial HTTP request for Jaff returns an encoded binary that’s been XORed with the ASCII string I6cqcYo7wQ,” Duncan reveals.

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The same as the initial Jaff variant, the new version targets over 400 file types. After completing the encryption process, it drops a ransom note to inform the victim on what happened and to provide information on how they can pay the ransom.

Because of its alleged connection with a large crime group, Jaff has the potential of becoming a major threat fast. WannaCry might have stolen the headlines for the past days, but Jaff is slowly growing to become a prevalent threat.

Related: New Jaff Ransomware Distributed via Necurs Botnet

Related: Windows 7 Most Hit by WannaCry Ransomware

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

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