Washington Warns Hackers Are Turning Up the Heat on the World's Freezers

The U.S. government says someone is quietly messing with the world's freezers — and it wants the industry to lock the doors. CISA, the FBI and three other federal departments issued a joint warning Thursday about an "ongoing cyber threat" aimed at internet-connected refrigeration and cold chain monitoring gear in supermarkets, cold storage facilities and beyond.

The agencies say the intrusions reach into critical infrastructure: food, agriculture, transportation and the shipping of medicine. If hackers get in, they could flip the temperature and trigger real-world damage — fire hazards, ruined inventory, even a shortened service life for the equipment itself. A separate fact sheet warns attackers may push units into relentless heating and defrost cycles.

The alert follows weeks of attacks across the UK and Europe. Two separate waves let hackers crank up the thermostat on freezers and chilling units in at least a dozen countries, defrosting food and wiping out produce. Some of the hit systems were remote-controlled refrigeration units made by Danish manufacturer Danfoss, which had already stopped shipping security updates to customers' freezers.

One attack reached a blood bank in France, where hackers raised temperatures in cold units holding donated blood — though the intrusion was stopped before blood supplies were compromised, according to TechCrunch. The U.S. Department of Defense is investigating a string of hacks targeting military freezers, Reuters reported. Signal and Silence first reported the attacks.

No group or government has been formally blamed, but security researchers have broadly pointed at Iran, and U.S. officials reportedly suspect the same. The federal agencies told affected industries to pull remote controls off the internet, strengthen passwords, patch what they can and retire gear vendors no longer support. "Every organization that depends on refrigeration and monitoring systems should assume it could be a target," said CISA acting cybersecurity chief Chris Butera.