External reconnaissance
Also known as external footprinting, external reconnaissance involves the use of tools and techniques that help hackers find information about a target while operating outside the target’s network. This exercise is stealthy and can be quite hard to detect since some reconnaissance tools are built to be evasive to monitoring tools, and others use requests that appear to be quite normal to servers.
External reconnaissance differs from internal reconnaissance as it is conducted before a threat actor has actually infiltrated an organization (it can also be conducted as an attack of its own that doesn’t infiltrate an organization at all if the threat actor isn’t aiming to conduct an advanced persistent attack). In comparison, internal reconnaissance is conducted after a threat actor has already breached an organization, and is conducted within a target’s network to gather as much intel as possible about the organization and its members...
