Since the coronavirus pandemic forced companies to enact sweeping work-from-home policies, the number of organizations whose devices have been compromised and forced to engage in malicious activity have at least doubled, according to new research released today.

The researchers behind the study – conducted jointly by Arctic Security and Team Cymru – believe many of the affected organizational devices may have been compromised with malware prior to the COVID-19 crisis, but were blocked from connecting to the internet for malicious command-and-control purposes by corporate firewalls. Home-based VPN connections, however, do not afford the same protections, and so now these devices are being activated, the researchers explain in a report (available here and here).

"Now those [botnet device] zombies are outside firewalls, connected to their corporate networks via VPNs, which were not designed to prevent malicious communications," said Lari Huttunen. senior analyst with Arctic Security, in a press release. The research report described corporate firewalls as functioning like dams obstructing malicious connections. But "when you rely on a VPN, it’s like digging a ditch to the side of that dam," Huttunen added in the report.

The activity most often observed in compromised organizations was scanning activity intended to find vulnerabilities to exploit in additional internet-connected devices.

The study looked at nine European countries and the U.S. According to the press release, the number of potentially compromised organizations in the U.S. doubled between January and March, and more than 50,000 organizations in the U.S. were infected prior to the work-from-home and social distancing edicts in mid-March.

In a typical week, Arctic Security would detect malicious signs of compromise in roughly 200 organizations in its own home country of Finland. But during the week of March 16, the company observed approximately 800 potentially compromised companie – about quadruple the normal amount. It was this observation that prompted the researchers to commence a study to see if other nations were experiencing similar trends under COVID-19 conditions.

Great Britain and Italy in particular experienced major increases in the number of organizations showing compromised device activity between January (over 3,000 orgs in the U.K., around 4,500 in Italy) and March (more than 12,000 orgs in the U.K., over 10,000 in Italy).