As hackers – many sponsored by Russia and China and authoritarian governments around the world – have stepped up cyber attacks on municipal services in a number of countries, Thessaloniki's agencies were shut down over an electronic intrusion.

That happened July 23, with Deputy Mayor of Business Planning, e-Government and Migration Policy Giorgos Avarlis saying the city – Greece's second-largest – closed its services and web applications, “so that proper investigations can be carried out and we do not risk being attacked again,” with no report what kind of defenses it has.

Speaking to local radio, Avarlis said that a malicious virus had been installed, with hackers asking for a “ransom” to “unlock” the files, although it wasn't said how much or if he was paid.

“We want to be fully assured that everything will work properly,” he said, clarifying that all of the municipality’s files are being secured without explaining how or identifying the source of the attack.