What type of malware can, for example, locks up a user's computer and then display a message that purports to come from a law enforcement agency that states the user must pay a fine for illegal activity?

I’d say platform as a service (paas) or application platform as a service (apaas) or platform base service is a category of cloud computing services that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.

Answerf3 key;