How were hackers able to make refrigerators blow 50°C air across French supermarkets. Refrigerators at French supermarkets have been hit by a cyberattack, causing them to blow 50°C hot air, sparking fires and spoiling food. Hackers targeted the central supermarket refrigeration systems, which "were running outdated firmware" as per Dutch supplier. The systems can be accessed remotely, allowing maintenance companies to monitor and adjust them without being physically present.