As Russia has tested every form of attack on Ukraine's civilians over the past decade, both digital and physical, it's often used winter as one of its weapons—launching cyberattacks on electric utilities to trigger December blackouts and ruthlessly bombing heating infrastructure. Now it appears Russia-based hackers last January tried yet another approach to leave Ukrainians in the cold: a specimen of malicious software that, for the first time, allowed hackers to reach directly into a Ukrainian heating utility, switching off heat and hot water to hundreds of buildings in the midst of a winter freeze.
Industrial cybersecurity firm Dragos on Tuesday revealed a newly discovered sample of Russia-linked malware that it believes was used in a cyberattack in late January to target a heating utility in Lviv, Ukraine, disabling service to 600 buildings for around 48 hours. The attack, in which the malware altered temperature readings to trick control systems into cooling the hot water running through buildings' pipes, marks the first confirmed case in which hackers have directly sabotaged a heating utility. 
Dragos' report on the malware notes that the attack occurred at a moment when Lviv was experiencing its typical January freeze, close to the coldest time of the year in the region, and that “the civilian population had to endure sub-zero [Celsius] temperatures.” As Dragos analyst Kyle O'Meara puts it more bluntly: “It's a shitty thing for someone to turn off your heat in the middle of winter.”
The malware, which Dragos is calling FrostyGoop, represents one of less than 10 specimens of code ever discovered in the wild that's designed to interact directly with industrial control-system software with the aim of having physical effects. It's also the first malware ever discovered that attempts to carry out those effects by sending commands via Modbus, a commonly used and relatively insecure protocol designed for communicating with industrial technology.
Dragos first discovered the FrostyGoop malware in April after it was uploaded in several forms to an online malware scanning service—most likely the Google-owned scanning service and malware repository VirusTotal, though Dragos declined to confirm which service—perhaps by the malware's creators, in an attempt to test whether it was detected by antivirus systems. Working with Ukraine's Cyber Security Situation Center, a part of the country's SBU cybersecurity and intelligence agency, Dragos says it then learned that the malware had been used in the cyberattack that targeted a heating utility starting on January 22 in Lviv, the largest city in western Ukraine.
Dragos declined to name the victim utility, and in fact says it hasn't independently confirmed the utility's name, since it only became aware of the targeting from the Ukrainian government. Dragos' description of the attack, however, closely matches reports of a heating outage at the Lvivteploenergo utility around the same time, which, according to local media, led to a loss of heating and hot water for close to 100,000 people.
Lviv mayor Andriy Sadovyi at the time called the event a “malfunction" in a post to the messaging service Telegram, but added, “there is a suspicion of external interference in the company's work system, this information is currently being checked.” A Lvivteploenergo statement on January 23 described the outage more conclusively as the “result of a hacker attack.”
Lvivteploenergo didn't respond to WIRED's request for comment, nor did the SBU. Ukraine's cybersecurity agency, the State Services for Special Communication and Information Protection, declined to comment.
