The Federal Bureau of Investigation (FBI) has determined that more than 100 U.S. businesses suffered Ryuk ransomware infections between August 2018 and mid-May 2019.

According to LexBlog, the FBI published a Flash update in which it revealed that the vast majority of these Ryuk ransomware attacks targeted logistics organizations, technology firms and small municipalities. The FBI explained how it was impossible to identify the infection vector in many of these attacks because of Ryuk’s ability to delete all files related to the intrusion.

However, the update did note how digital attackers had equipped the threat with the ability to steal credentials and abuse the Remote Desktop Protocol (RDP) for the sake of infecting a machine, establishing persistence and downloading additional network exploitation controls.

Additionally, the FBI explained in its Flash that it had found a new version of Ryuk. Samples of this variant used ransom notes that did not identify the exact ransom amount but instead instructed users to contact one of several email addresses. Only when the victim complied with these instructions did the attackers specify the ransom amount, identify a bitcoin wallet for payment and provide a sample decryption of an affected file or two.

Putting Ryuk Into Context

Ryuk has had a busy year. In August 2018, Check Point identified an attack campaign that targeted enterprises located around the world and encrypted hundreds of PCs and data centers in the process. Several months later, a Ryuk campaign disrupted the publication schedules of the Chicago Tribune and other Tribune Publishing newspapers around the U.S., as reported by CSO Online. It wasn’t long thereafter that news from Krebs on Security emerged about how the ransomware had affected systems owned by cloud hosting provider Dataresolution.net.

What makes Ryuk stand out among other crypto-malware strains is that it relies on TrickBot and Emotet for delivery, as Cybereason and CrowdStrike learned separately. Both of these families are significant threats on their own. Illustrating this fact, the United States Computer Emergency Readiness Team (US-CERT) said Emotet was “among the most costly and destructive malware affecting state, local, tribal, and territorial (SLTT) governments, and the private and public sectors.”

How to Defend Against Ransomware

Security professionals can help defend their organizations against ransomware by using artificial intelligence and automation to discover attack campaigns that employ sophisticated tactics as a means of evading detection. Organizations should also employ an endpoint management solution to maintain visibility into all their endpoints in the fight against ransomware.