Cyber researchers remain sceptical of NoName057’s alleged claim of responsibility. The group is not known to conduct operations beyond distributed denial-of-service (DDoS) attacks and has a history of false attributions.
In late August, freezers at at least six U.S. military bases were forced into defrost mode, as in France.
Authorities in several countries are investigating the attacks and warning supermarkets about possible further incidents.
Until now, only supermarkets were known to have been affected by the freezer hacks.
DDoS attacks flood a website or online service with traffic in an attempt to take it offline or make it inaccessible.
Noname057(16) and Z-Pentest Alliance posted that they had successfully hacked Danfoss, prompting speculation they were behind the freezer incidents.
Experts including Dewhurst said the attacker or attackers had to gather public IP addresses of the devices to build a target list, then plan methods and timing. French authorities said fridges used in medical facilities to store donated blood were hit by recent cyber-attacks by unknown hackers. The French Blood Establishment (EFS) said cold rooms storing blood were impacted.
No health impact has been identified and no loss of blood products is to be reported, the EFS said.