Cybercriminals took remote control of digital thermostats on fridge display cases in supermarkets in Belgium, Luxembourg and Sweden. They turned the cases into makeshift ovens by setting them to defrost non-stop. Temperatures inside rose to unsafe levels, the affected chains said.
Hypermarkets in France were hit first, and there was damage there too.
See also: Hackers thaw freezer displays in up to 700 shops in France
EU commissioner Christophe Hansen called the attacks a deliberate attempt to shake food supplies in the EU. Damage in Europe runs to tens of millions of euros, and losses from closed shops come on top.
In Belgium, hackers hit dozens of shops run by Delhaize, Carrefour, Spar and Intermarché. Spokespeople for the chains said an IT incident switched on warming in the cooling systems, according to the Belgian news site 7sur7. Store managers pulled fresh goods from sale, and the federal prosecutor's office opened a criminal investigation into sabotage.
Technicians in Belgium and Luxembourg are racing against the clock, the German paper Bild reported. It says similar incidents have hit shops in both countries. Refrigeration technicians at Sabcobel say a software update is not enough and the control units have to be replaced physically.
In Sweden, the ICA and Coop chains reported widespread failures overnight. Temperatures in their display cases jumped from below zero to more than 38 or 50 degrees. The paper Sweden Herald reported that a local shop in Sjöbo closed and the spoiled goods were thrown out.
The attack also hit IKEA restaurants and butcher shop chains, where alarms went off at dawn.
Experts say many of the shops had protection. Even so, the hackers exploited basic weaknesses in equipment that retailers connect to the internet. An analysis by Le Figaro says the breach is part of a wider series of attacks, including earlier ones in France, where the damage was catastrophic.