Viasat officials have confirmed the report by SentinelOne researchers that the malware, known as “AcidRain,” was used in a cyberattack that crippled thousands of Viasat customers’ modems.

AcidRain, a modern malware attributed to Russian state threat actors was discovered under the name “ukrop” for one of AcidRain’s source binaries.

According to SentinelOne researchers Juan Andres Guerrero-Saade and Max van Amerongen, the malware is an executable file for MIPS, the hardware architecture for the modems used by Viasat customers.

The researchers also discovered similarities between AcidRain and a “dstr,” the name of a wiper module for VPNFilter.

On Wednesday, Viasat confirmed the researchers’ investigation. According to Viasat, the attackers gained unauthorized access to a trust management segment of the company’s KA SAT network.

The attackers gained access by exploiting a misconfigured VPN after which they expanded their reach to other segments.

“The attacker moved sideways through this trusted management network to a specific network segment used to manage and operate the network, and then used this network access to execute legitimate, targeted management commands on a large number of residential modems simultaneously,” Viasat explained.