WannaCry Lives On in 145K Infected Devices

Two years after the WannaCry ransomware attack blitzed through major organizations and shut down manufacturing and operations, the malware still exists on an estimated 145,000 devices, continuing to attempt to spread to unpatched versions of Microsoft Windows.

Internet of Things security vendor Armis over a six-month period collected data from honeypots and DNS cache servers and found that number of devices remain infected with the WannaCry ransomware. And nearly 60% of manufacturing and 40% of healthcare organizations have had at least one device compromised by WannaCry, the company found.

The continued success of WannaCry is mainly due to unpatched versions of Microsoft Windows that are embedded in hard-to-update industrial and enterprise devices, says Ben Seri, vice president of research at Armis.

"Often these systems are set up when the device—whether manufacturing, a healthcare, or retail—is delivered and the company does not want to update it, because they are concerned that doing so can lead to business disruption," says Seri, whose company today published its WannaCry data.

WannaCry has successfully attacked an average of 3,500 systems per hour worldwide over the past six months.

WannaCry first started spreading on May 12, 2017, infecting Microsoft Windows systems using an exploit stolen from the National Security Agency—known as EternalBlue—that targeted a vulnerability that had been patched by Microsoft two months before. The ransomware attack propagated on its own, placing it in the class of programs known as a worm, and quickly spread to 74 countries in the early hours of the attack.

The attack hit healthcare systems and manufacturers the hardest, as they had Microsoft Windows embedded in critical operations and information technology that the organizations needed to continue to operate. The attack disrupted the U.K.'s National Health Service, causing surgery delays and cancelled appointments. FedEx service faced disruptions and auto manufacturers such as Nissan and Renault suffered from the attack.

"In industrial networks, much of the security of the organization relies on segmentation of the network—which is good and you should do that—but once WannaCry gets in, the infection spreads quickly," Seri says.

Armis took a census of the current WannaCry population by using a network of honeypot servers to register the source of attack traffic. More than 145,000 devices appeared to be compromised with WannaCry at some point during the past six months. The company attempted to take into account systems behind routers that can sometimes appear as multiple systems due to the dynamic assignation of IP addresses.  

In addition, the company studied DNS traffic for signs of any requests to thee kill switch—a domain that WannaCry attempts to contact following an infection, and whose existence will be a signal to the program to stop its attempts at infection. The company examined more than 10,000 DNS servers in 120 countries to determine how many requests were made to the kill switch. The data suggests that vulnerable systems are still being infected with the original version of WannaCry - which checks for the kill switch - at a rate of roughly one compromise per second.

Companies and organizations that have systems with embedded versions of Microsoft Windows are at greater risk of WannaCry because those systems are often not regularly updated, Armis' Seri says. In many cases, the manufacturers of that equipment don't provide regular updates. In other cases, the organization does not have specific patch windows to apply software updates.

To make matters worse, the companies often also lack additional security, he says. "These reasons are also the reason many of them don't run any endpoint security, and thus are even more likely to be compromised by WannaCry, or similar malware," he wrote in an analysis posted to Armis' site.

An interesting anomaly in the data is that a relatively small country, Vietnam, accounts for more than 10% of the attacks, according to Armis. The issue for companies in the country is that Internet service providers block attempts to connect to the kill-switch domain, removing that safety net and leading to a higher number of infections. 

Armis found that healthcare organizations, manufacturers, and retail companies have high rates of older versions of Windows, with at least 60% of computers in each industry running Windows 7 or older.

The first step for companies is to gain continuous and consistent visibility into their networks and what devices are connected and operation systems are running, Seri says.

"This is not something that you do once in a while," he says. "You need to continuously know what is running and what is vulnerable."

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