France investigates cyberattack that overheated supermarket refrigeration systems

French authorities are investigating a cyberattack that remotely altered refrigeration systems at hundreds of supermarkets, raising temperatures, triggering defrost cycles and forcing retailers to discard spoiled food.

French minister Roland Lescure told parliament on Tuesday that 700 of the country’s 10,000 supermarket sites had been affected and had disconnected the compromised platform. Earlier estimates varied as retailers inspected their stores. Chains reporting disruptions included Carrefour, Monoprix, Intermarché, Netto and Coopérative U.

Temperatures in some refrigerators and freezers reportedly reached 50 degrees Celsius (122 Fahrenheit). Some locations also reported fires, damaged equipment or activated sprinkler systems. Retailers said food losses ran into millions of euros, though a definitive total was not available.

The attack targeted internet-connected refrigeration controls, including equipment made by Danish company Danfoss. Danfoss said many affected controllers were older products that no longer received security updates or were running outdated firmware. Cybersecurity experts cited by Reuters said exposed internet interfaces and failures to install available updates appeared to have made the systems vulnerable, although investigators have not publicly identified the exact method used.

France’s cybersecurity authorities advised operators to disconnect affected equipment, reset unauthorized changes, install updates and restore remote access only through secured networks. They warned that attacks could still be continuing.

No group has claimed responsibility, and investigators had received no public ransom demand as of Tuesday. The Paris prosecutor’s office has opened a cybercrime investigation to identify those responsible and assess links between the intrusion, food losses and reported fires.