How SonicWall Signature “Families” Block Emerging Ransomware Variants
When you look at the most damaging network security invasions over the last year, you see a recurring pattern: leaked government cyber tools being repurposed by cybercriminals. The compromised NSA toolset leaked by Shadow Brokers was devastating in many respects. These were highly targeted tools that many nation states wish they had the operational capacity to deploy.
But the tools developed by the NSA fell into criminal hands, who used them not for state-backed cyber espionage, but for capital gain. They repurposed these tools into WannaCry, Petya and, most recently, BadRabbit, as a means to install ransomware, encrypt information and keep it hostage until a targeted victim pays to release it, typically via Bitcoin.
Alas, sometimes victims pay and the data is still not released. Sometimes, other actors see an organization has been held hostage and sends their own ransom demands, even though they are not affiliated with the original ransomware creators. The victim organization pays for this misdirection but still cannot unlock their files. They are out of the money and damages are incurred. “There is no honor among thieves,” as they say.
WannaCry, Petya and BadRabbit form a “family” of ransomware variants developed from the same leaked NSA tools. It is when there are these multiple attacks using the same family of exploits that SonicWall can give you breathing room and help you sleep at night.
To explain, first let me discuss how signatures work in our next-generation firewalls (NGFWs). Individual signatures exactly match bit patterns from IP-based frame payloads to detect a specific variant of malware. Our award-winning Capture ATP technology, a multi-engine network sandbox, not only stops unknown and zero-day threats from entering networks, but also helps create new signatures for detecting emerging malware.
Few vendors look at both incoming and outgoing packets for malware, as it can be a large performance hit to do both. Most vendors are only concerned with traffic going from the internet to the trusted zones and only inspect this pattern. Yet SonicWall inspects every single packet in each direction.
Why? Well, if you own a network and somehow a device is compromised, the only way you will find out is by seeing what it sends out. Is it talking to a command-and-control server (C&C)? Is it sending malware out, as infected machines do? Without scanning every packet, you do not have visibility of your internal network. While it is important to block incoming malware, it’s also important to determine what machines may have been infected and are trying to send data outside your organization.
This brings us back to our “family” of signatures. Have you ever wondered why SonicWall uses a different naming convention than other well-known malware strands? It’s because we find them first, and give them their own names. Other vendors do this too, but we are vastly different. I am proud to say that SonicWall is extremely competent in creating a family of signatures to cover many individual signatures with one pass. SonicWall uses a fast memory-tree lookup as packets pass through the NGFW with our family of signatures, so only one lookup is needed. This is an extremely fast method of traffic processing.
Sometimes in sales, we have to quote statistics in answer to questions, such as “How many signatures do you store on the firewall?” And we dutifully respond, “Over 32,000 locally, with more in the cloud.” But this only tells part of the story. With our family of signatures, one family will catch 100 or more variation of one signature.
Going back to WannaCry, SonicWall created a family that caught WannaCry right after it was announced to the public. Since the NSA leak variants caused Petya and BadRabbit derivatives, the family signature in your SonicWall firewall blocked all these new attack vectors.
Even though these new variants were targeted delivery to networks, SonicWall blocked all these different bit patterns as part of our WannaCry signature family. The signature updates were performed in the background – as you enjoyed the holidays with your friends and family.