While pro-Russian hacker groups claimed the attacks on Wednesday, it is notoriously difficult to attribute a cyberattack to a specific actor definitively, and those groups quickly deleted the claims, according to the BBC.

Some cybersecurity experts say Russia is one of the main suspects. Xavier Bellekens, CEO of cybersecurity firm Lupovis, told POLITICO that clues pointed to "a Russian state-sponsored threat actor." However, a report from cyber defense firm Sekoia noted that "Iranian-aligned actors have an established record" of targeting supermarkets, for instance in the U.S. and Israel.

Cybersecurity authorities in countries affected by the hacks haven't publicly attributed the attacks.

Marie Thirion contributed to this report.