Thousands of websites, including the Information Commissioner's Office, the Scottish NHS helpline and the Student Loans company along with hundreds of other central and local government sites appear to have been hijacked by hackers to mine cryptocurrency like Bitcoin or Ethereum.
The services were infected with malware called Coinhive, which sits on a website and steals the processing power of its visitors' devices to mine Bitcoin or alternative coins that are stored in an anonymous digital wallet, to be withdrawn at a later date.
This is the kind of thing that gives cryptocurrency a bad name and makes govts mad.