Networked digital video recorders have been harnessed for all sorts of ill intent over the past few months, including use in a botnet that disrupted large swaths of the Internet. But a different sort of malware hit the DVRs used by the District of Columbia’s closed-circuit television (CCTV) surveillance system just one week before Inauguration Day. The Washington Post reports that 70 percent of the DVR systems used by the surveillance network were infected with ransomware, rendering them inoperable for four days and crippling the city’s ability to monitor public spaces.

The CCTV system, operated by the District’s Metropolitan Police Department and supported by the DC Office of the Technology Officer (OCTO), began to be affected on January 12. Police noticed they could not access video from four DVRs. Washington DC Chief Technology Officer Archana Vemulapalli told the Post that two forms of malware were found on the four systems, and a system-wide sweep discovered additional DVR clusters that were infected.

The infections were limited to the local networks that the DVRs ran on, and this ransomware did not extend to the District’s internal networks. While the investigation is ongoing, the malware likely was able to take over the systems because each site was connected to the public Internet for remote access. Vemulapalli told the paper no ransom was paid and the system was restored to full functionality before Inauguration Day.

Ars attempted to contact DC OCTO for further details on the DVR systems and the networks they are connected to, but we have yet to receive a response. We’ll update this story as more details become available.