European supermarkets were hit by a hack targeting fridges and freezers on Monday, raising temperatures and causing mass spoilage in the second such attack in as many months.

The attack targeted dozens of supermarkets across seven European countries, affecting supermarket groups Ahold Delhaize and Colruyt in Belgium and Luxemburg as well as Swedish chains ICA and Coop. At least one Ikea store was also hit, according to Reuters.

The geographic scope of the attack was notably larger than October’s, which only hit supermarkets in France, though the total number of stores affected is believed to be lower.

The attack is believed to have used a similar technique to the previous one, remotely switching fridges and freezers to defrost mode, causing them to warm to as high as 50C (122F).

A sales manager at an ICA franchise store in Stockholm told Reuters on Monday that the attack occurred at around 2AM, but was not noticed until hours later.

At least some of the units affected used temperature control technology from Danish firm Danfoss, the news outlet added, which was the attack vector for the October attack.

Stephan Moelans, chief executive of Sabcobel, which operates Delhaize’s systems, told Belgium’s Belga news network Monday that the company had been “working all night and morning to disconnect the affected units from the network”.

Since the French attack, he added, the company had been working to protect customers’ fridges against the vulnerability, but that the units needed physical modifications, not just software updates.

“The simplest solution is to manage the fridges over a secure internet connection. Most of our customers switched to that after the attack in France,” Moelans added.

The attacks have raised fears that this could be the beginning of a new front in cyber warfare. EU agriculture and food commissioner Christophe Hansen told Politico that the attacks would be discussed at the next meeting of its security college.

“Europe’s food supply chain must be prepared for new and evolving threats,” he added. “The repeated cyberattacks on supermarkets are deeply concerning, causing economic losses for retailers and empty shelves for consumers.”

It is unclear who is behind the latest attack, and no concrete suspects have been found to be behind the attack in October.

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