1. A method of detecting malicious software, wherein the method comprises: intercepting a request to perform an activity in a processing system; determining an entity associated with the activity, wherein the entity comprises at least one of: a requesting entity of the activity; and a target entity of the activity; analysing the entity and the activity to determine if the request is associated with malicious software; and in the event that the request is determined to be associated with malicious software, restricting the request to perform the activity in the processing system.