Ransomware attacks are on the rise. SonicWall reported a 109% increase in ransomware the US during the first half of 2020. Due to relatively low execution costs, high rates of return, and minimal risk of discovery compared with other forms of malware, ransomware has quickly become a preferred method of attack for cybercriminals.

Although computer systems remain the most common source of ransomware infection, Internet of Things (IoT) devices are also prime targets for several reasons, including the fact that hackers know enterprises often have less visibility into these devices, and can therefore inflict devastating effects without detection. In addition, IoT devices are often not built with security in mind, leaving them vulnerable for exploits. IoT-based attacks can also spread across the network very quickly to maximize damage, and ransomware can render the physical functions of that device inaccessible until the ransom is paid. 

Unfortunately, there’s a lot of finger-pointing when it comes to who is responsible for bolstering IoT security. Often, it’s up to individual organizations to protect themselves from IoT-based attacks.

Of all the types of ransomware, one of the most damaging and infamous is WannaCry. It is estimated to have affected more than 200,000 computers across 150 countries, with total damages ranging from hundreds of millions to billions of dollars. WannaCry, as well as other forms of malware and ransomware, leverage a well-known exploit named EternalBlue. It exploits a vulnerability in the Window’s Server Message Block version 1 (SMB v1) protocol, which allows the malware to spread to all unpatched Windows systems from XP to 2016 on any network that has this protocol enabled. 

Although WannaCry was first detected in May 2017, according to Safety Detectives, it still represents nearly half of all reported ransomware incidents in the US today. All EternalBlue-based malware (including WannaCry) exploits the same Windows vulnerability. Since these attacks are still increasing three years later, it’s evident that there are plenty of unpatched Windows systems still out there.

And again, while WannaCry primarily targets computers, IoT devices were not — and are not — immune.

How One Hospital Stopped a WannaCry Attack
In 2019, a European hospital system discovered their ultrasound devices were infected with WannaCry. Several digital imaging and communications in medicine (DICOM) devices were also affected because they were running old versions of MS Windows operating systems. These devices couldn’t be patched without breaking the device manufacturer’s warranty and, due to the expense of these devices, couldn’t easily be replaced. 

Fortunately, the hospital acted fast and was able to stop this attack. Specifically, they:

• Confirmed the existence of the infection on the imaging machines.
  The hospital selected one of the suspicious DICOM devices, an ultrasound in the maternity section of the hospital. This was a particularly dangerous case because some of the images and reports could be stolen and held for ransom, or worse, the device could be taken control of and rendered unusable. They performed a traffic capture on the ultrasound device and found a significant number of flows from the ultrasound to the network, using SMB Over TCP (port 445). Since this was the preferred port and known exploit for EternalBlue/WannaCry, it confirmed that the machine was infected.

• Applied security profiles and isolated the affected devices.
  Since the ultrasound device couldn’t be patched or upgraded, they couldn’t eliminate the infection. However, the hospital was able to contain it and continue using infected medical devices without worrying about infecting the broader network or losing the ultrasound images and files. In order to do this, the hospital used a security solution that could segment and isolate certain devices on the network, so that the infection could be contained within the ultrasound device, preventing propagation through the network. The IT team then applied policies to the ultrasound device to ensure that no UDP/TCP ports were opened, except those explicitly allowed by the imaging staff and IT managers. 

• Monitored unattended devices and remained vigilant. 
  The action didn’t stop when the hospital isolated the known impacted devices. Hospitals and other organizations that have had their computer systems impacted by multiple rounds of WannaCry outbreaks need to confirm that any medical devices (especially those running old versions of MS Windows Operating Systems) haven’t also been infected. The European hospital verified other devices weren’t affected, and continued to closely monitor for any suspicious activity.

The Road Ahead
Cybersecurity experts all agree that ransomware attacks are only going to accelerate and could represent an increased threat to IoT devices in 2020 and beyond. In addition to protecting your computer systems and company data from the threat of a ransomware attack, it is critical to review and update your current IoT security practices, especially for mission critical endpoints such as medical devices and industrial control systems.

Ransomware isn’t going anywhere, but we can make sure we’re prepared for the next time it strikes.

This article was originally published to Dark Reading on September 25, 2020.