Rafe Pilling, a senior director at Sophos, a cybersecurity firm, said the relatively unsophisticated nature of the attack on French supermarket freezers — hackers used default passwords to access fridge controls — was in line with Iranian capabilities. “The attacks themselves were not particularly complex,” he said.

Pilling said there was now a presumption “the French attacks and a wave of rogue defrosting hacks across Europe last week were linked.” The Guardian’s analysis, written by its global technology editor Dan Milmo, described the incident in its standfirst as a defrosting hack attributed to Iran that was not particularly complex, with a presumption that it is linked to others across Europe.

France has attributed the attack on supermarket fridges to hackers operating under the Islamic Revolutionary Guard Corps, a key branch of Iran’s military establishment. France’s foreign minister described it as an act of “unprecedented scale and unprecedented aggression” and promised “Europe-wide sanctions” would be imposed against those responsible. Some refrigerators had their temperature turned up so high they caught fire, and in the hours after the hack, supermarket employees dumped piles of perished meat and melted ice-cream into rubbish containers. Photographs credited to Lucien Libert/Reuters showed empty refrigerators at an Intermarche supermarket in Paris the day after the cyber-attack and an employee filling boxes of perished goods outside the store.

The French announcement follows attacks on industrial freezers at an Israeli food production plant in May and a wave of freezer malfunctions that spoiled food at US military bases in August that are now reportedly being treated as a suspected hack. Those attacks have not been officially attributed to Iran, but the French announcement is the first to implicate the state in this type of hack.

The fridge hacks came as the UK’s national cybersecurity centre warned that the country was in the “foothills” of a new level of cyber threat and should expect a “huge rise” in the volume of incidents. Within that warning, the centre said: “The main concern is AI, a technology now capable of highlighting previously unforeseen flaws in IT systems and helping attackers plan and carry out attacks.”

Milmo wrote in the outlet’s cybercrime analysis that “the underlying context of the fridge attacks is not AI but geopolitics.” He noted that “the refrigeration system vulnerabilities were relatively easy to find and exploit,” and concluded that “a combination of groundbreaking technology and tense global relations makes for an alarming landscape.”

The Guardian’s analysis opened with the line “Iranian hackers like to send a message.” In 2023 a state-backed group interrupted TV streaming services in the United Arab Emirates to broadcast a deepfake report on the war in Gaza. In the same year, hackers affiliated with Iran displayed the slogan “down with Israel” on the screens of water-control equipment made by an Israeli firm. The analysis said: “There was no message this time, but the disruption made headlines around the world.”

The Guardian’s analysis said hostile cyber operations against the west “tend to come from a vexatious quartet of China, Russia, Iran and North Korea.” The analysis said China “has focused on industrial espionage and mass data gathering,” Russia “on disrupting enemy infrastructure and spreading disinformation,” and North Korea “on hacking crypto exchanges because it needs money.” Iran, according to Pilling, wants to put “a shot across the bow” of its enemies. “In general Iran uses cyber-attacks to project power internationally and to signal their political displeasure with regional and international adversaries,” Pilling said.

The Guardian separately asked in a linked headline: “Hot fridges, a fake nuclear alert and a $6bn heist: are we in the foothills of a hacking epidemic?”