FBI and CISA Warn Hackers Can Set Industrial Freezers on Fire

U.S. government agencies warned Thursday of an "ongoing cyber threat" to internet-connected industrial refrigeration, after hackers compromised freezers in supermarkets worldwide, on U.S. military bases, and at least one blood bank.

CISA, the FBI, and the Departments of Agriculture, Health and Human Services, and Transportation issued the joint warning. They said hackers are targeting and compromising refrigeration and cold chain monitoring systems in grocery stores and cold storage facilities — infrastructure that spans food, agriculture, transportation and medicine-shipping.

The stakes are physical, not just digital. "If successfully exploited, the actors could change the temperature and possibly cause physical impacts such as fire hazards, loss of inventory and changes to the service life of the system," the agencies warned.

What does this change for operators?

The practical question for anyone running cold storage: how exposed is your kit? The agencies' answer is blunt. They urged affected industries to:

• Remove remote control systems from the internet
• Change and strengthen passwords
• Apply patches where possible
• Retire equipment no longer supported by the vendor

In a separate fact sheet, the departments added that hackers may attempt to "force units into continuous heating and defrost cycles, which can cause widespread inventory loss and equipment hazards." An unsupported freezer isn't just a maintenance risk anymore — it's an attack surface.

How the attacks played out

The warning follows several waves of attacks on industrial refrigeration units across the United Kingdom and Europe in recent weeks. Two separate waves let hackers crank up temperatures on freezers and chilling units in at least a dozen countries, spoiling defrosted food and destroying produce.

Some affected systems used remote-controlled refrigeration units made by Danish company Danfoss — equipment whose vendor had stopped providing security updates to customers' freezers. That detail matters for procurement teams: end-of-support status now carries a quantifiable cyber risk, not just a warranty inconvenience.

Hackers also hit a blood bank in France, forcing its refrigerated units to raise temperatures in cold storage containing donated blood supplies. Staff stopped the attack before it compromised the blood stores. The U.S. Department of Defense is investigating a spate of hacks targeting military freezers, according to Reuters. Signal and Silence first reported the intrusions.

Who's behind it?

The U.S. government has not formally attributed the hacks to any group or state. But security researchers have broadly attributed the attacks to Iran, and U.S. officials also reportedly suspect Iran is the likely culprit.

CISA's acting cybersecurity chief Chris Butera put the guidance in one line: "Every organization that depends on refrigeration and monitoring systems should assume it could be a target." That includes small grocery chains and regional distributors, not just the marquee names — the attacks already documented span a dozen countries and multiple continents.

For operators, the near-term move is straightforward: audit which refrigeration controllers are internet-facing, isolate them, and inventory anything past vendor support. The next wave of attacks, federal agencies are signaling, won't wait for attribution.