Cyber-attacks which see hackers get inside computer networks and lock the owners out until they pay a ransom present "the most immediate danger" to UK businesses in cyber-space, the head of the National Cyber Security Centre (NCSC) has warned.

https://www.bbc.co.uk/news/uk-58877433?mc_cid=70b7b62985&mc_eid=72e89a1d85