US government warns of ongoing cyberattacks on industrial freezers at supermarkets and military bases

US agencies issue a joint warning

CISA, the FBI and the Departments of Agriculture, Health and Human Services, and Transportation warned in a joint statement on Thursday of an "ongoing cyber threat" to internet-connected refrigeration and cold chain monitoring systems, according to TechCrunch. The agencies said hackers are actively compromising equipment in grocery stores and cold storage facilities, and that the campaign touches critical infrastructure across the food, agriculture, transportation and medicine-shipping sectors.

The advisory describes what a successful compromise enables: attackers can change temperatures and potentially cause physical impacts such as fire hazards, loss of inventory and shortened equipment life. In a companion fact sheet, the agencies added that intruders may force units into continuous heating and defrost cycles, which can produce widespread inventory loss and equipment hazards.

Attacks across a dozen countries

The warning follows several waves of attacks on industrial refrigeration units across the United Kingdom and Europe in recent weeks, TechCrunch reports. Two separate waves let hackers raise temperatures on freezers and chilling units in at least a dozen countries, spoiling defrosted food and destroying produce. Some of the affected systems were remote-controlled refrigeration units made by Danish company Danfoss, which had stopped providing security updates for some customers' freezers.

The campaign also reached more sensitive targets. According to TechCrunch, hackers struck a blood bank in France, causing its refrigerated units to raise temperatures in cold storage holding donated blood supplies, although they were stopped before any blood stores were compromised. Separately, the US Department of Defense is investigating a spate of hacks on freezers run by the military, according to Reuters. The intrusions were first reported by Signal and Silence.

Iran suspected but not officially blamed

The US government has not attributed the hacks to a particular group or government. Security researchers have broadly attributed the attacks to Iran, TechCrunch reports, and US officials also reportedly suspect Iran is the likely culprit.

Recommended defenses

The joint advisory urges affected industries to remove remote control systems from the internet, change and strengthen passwords, apply patches where possible, and retire equipment that vendors no longer support.

Chris Butera, CISA's acting cybersecurity chief, said every organization that depends on refrigeration and monitoring systems should assume it could be a target.

Why it matters

The incident is a stark example of unglamorous, internet-connected hardware turning into a physical safety problem. Refrigeration controllers are cheap, widely deployed and easy to overlook, yet they underpin the cold chain for food and donated medical supplies, and the government says misused units can create fire hazards. The Danfoss detail also shows how equipment past its support date keeps running in production environments and becomes a standing liability. For defenders, the guidance comes down to fundamentals: keep control systems off the public internet, and decommission what can no longer be patched.