Ransomware crews now hit doors, HVAC and building systems

Ransomware is no longer only about encrypted files and stolen data. A report from The Register pulls together a run of recent cases where attackers went after the systems that run buildings: door locks, badge readers, heating and cooling, and refrigeration.

From fridges to front doors

The most recent example is the attack on remote-controlled refrigeration at French supermarkets, which we covered this week: temperatures were pushed up, food spoiled and, according to The Register, some units caught fire. In August, a ransomware attack on building management at a Canadian hospital disrupted door access controls, central HVAC monitoring and the issuing of staff badges.

Incident responder Tim Beasley of Semperis described a case where a victim refused to pay and the attacker answered by locking everyone out of the offices. Police had to break windows so staff could get back in. The customer still did not pay.

How exposed building systems are

Building automation systems (BAS) control lighting, HVAC, energy, water, door locks, cameras and fire panels. A Q3 2026 report from Armis Labs found that:

• 91% of these systems communicate over insecure protocols such as BACnet, KNX, Modbus and LonWorks, which were designed for closed networks;
• 73% of organisations have known exploited vulnerabilities in at least one BAS;
• 73% run types of BAS that have already been used in ransomware attacks.

ServiceNow's Michael Freeman told The Register that building systems are also a good place for intruders to hide and then move into IT networks, and that attackers now use AI to learn obscure controllers and operating systems. Industrial security firm Dragos says ransomware incidents against industrial organisations keep rising, from 1,020 in Q1 2026 to 1,140 in Q2, and estimates that fewer than 10% of operational networks have enough monitoring.

What it means at home

These are commercial systems, but the lesson carries over to smart homes: anything that controls locks, heating or cameras deserves the same care as a laptop.

Our explainer on Matter and Thread covers local control, and the smart thermostat buying guide lists what to check before you connect heating to an app.