Hackers turned Europe's supermarket freezers into ovens

Overnight into Monday, someone got into the refrigeration systems of supermarkets in several European countries at once and cranked freezer temperatures up to 50 degrees Celsius. Staff opened the stores in the morning to find warm cabinets full of spoiled food.

Belgium and Luxembourg took the worst of it: around 40 Delhaize stores, roughly 15 Belgian Carrefour locations and five Spar shops. In Sweden, ICA and Coop stores were hit, seven of Coop's 800 shops among them. Similar failures are reported from Ireland, where 13 SuperValu stores were affected, and from Estonia.

The method is simple and nasty. The head of Sabcobel, the Belgian company that runs Delhaize's refrigeration, called it a cyberattack: the evaporators were remotely switched into defrost mode. At one Stockholm store the attack started at 2 a.m. and nobody noticed until 5:30. One Delhaize branch near Brussels put its losses at 100,000 euros in produce alone, not counting the days it stays closed.

This is the second hit of its kind. In October, hundreds of French supermarkets were attacked the same way, and some stores caught fire. Nobody knows who is behind it, nobody has claimed it, and no official link between the two waves has been confirmed. Belgium's and Sweden's national cybersecurity centres say they are watching closely.

A freezer that talks to the internet turned out to be as weak a spot as a forgotten router. Someone figured that out before the supermarket chains did.