Robert Silvers. Photo credit: Handout

In December, the Department of Justice (DOJ) charged three males in New Jersey, Pennsylvania and Louisiana with creating and executing the Mirai botnet, which crippled a host of popular websites across the United States in October.

Though the attack became one of the largest distributed denial of service attacks (DDoS) and most prominent hack into internet of things (IoT) consumer devices ever, finding the perpetrators was no easy feat.

As Rob Silvers, partner in Paul Hastings' privacy and cybersecurity practice, and former assistant secretary for cyber policy at the U.S. Department of Homeland Security (DHS) under the Obama administration knows, cybercrimes can be difficult to track, especially when dealing with botnets.

Silvers spoke with Legaltech News about the efforts that go into catching botnet creators, what he accomplished at the DHS, and what last year's DDoS attack means for the future of IoT devices.

Legaltech News: Can you speak to your work investigating the Mirai botnet?

Rob Silvers: Until January 2017, I was the assistant secretary for cyber policy at DHS. I was in office when the most high-profile use of the Mirai botnet took place, which was in October of 2016.

We quickly were able to determine that the Mirai botnet was the weapon that had been used to cause all that damage. But we weren't sure at that time was who was behind it, who had written Mirai, who had directed Mirai to comprise all of these poorly secure internet devices and directed them to push all their traffic towards this one internet utility.

When I left DHS at the turn of the Obama to Trump administration in January 2017, we still didn't know who the attackers were. Obviously a criminal investigation ensued and the government was able to determine that these three individuals wrote the program, actively sought vulnerabilities in internet connect devices that they could exploit to grow the size off their botnet.

They also used that botnet in various ways to make money, including through launching denial of service attacks and demanding payment in bitcoin to stop the attacks.

How difficult can it be to identify the perpetrators behind botnets attacks?

It can be quite difficult to find a perpetrators in a case like Mirai, it takes careful investigative work. Sometimes the perpetrators are assisted by the fact that they are using anonymizing web browsers, which makes it difficult to track their search website history. They're also transacting in bitcoin or other cryptocurrencies, which are very difficult, though not impossible, to trace.

Sometimes you are really relying on human error and various clues that people leave, so it really becomes a digital forensics investigation, and that can take months or years.

What were you tasked with as assistant secretary for cyber policy at DHS?

I was responsible for developing and implementing the department's cybersecurity policies and strategies. One of the key priorities we had was the security of the IoT devices, and we were working on best security practices guidance for IoT manufactures when the Mirai attack in October occurred.

What we did shortly after was accelerate the development of our guidance, which we released in November 2016. Those guidelines really create an organizational framework for IoT manufacturers when it comes to managing cyber risk in IoT products.

How does a botnet grow to such a size?

The indictment made clear that they were always actively looking for additional vulnerabilities that they could exploit to grow the size of their botnet. Trial and error is one way of doing that, targeting widely circulated devices and seeing if they could find a way in. That's what hackers do all the time, they try and they try and they try until they succeed in breaking into something.

This is a really important lesson for the manufactures of internet connected products; the need to design their products bearing in mind that there are going to be very sophisticated bad guys who from day one are trying to break into them.

All three Mirai botnet perpetrators were in their early 20s. Were you surprised they were so young?

They may have been young and they may not have the appearance of what you think of a classic grizzled criminal, but that's the face of hacking.

These actors as alleged in the indictments were quite sophisticated. They knew what they were doing. They weren't just writing code for the fun of it, they were writing malicious code, deploying it and demanding money through extortion to stop the damage they were causing to innocent parties. And then they were renting out their tools to others to do the same thing. So this was a real criminal enterprise.