Internal reconnaissance
Unlike external reconnaissance attacks, internal reconnaissance is done on-site. This means that the attacks are carried out within an organization's network, systems, and premises. Mostly, this process is aided by software tools. An attacker interacts with the actual target systems in order to find out information about its vulnerabilities. This is the main difference between internal and external reconnaissance techniques.
External reconnaissance is done without interacting with the system, but by instead finding entry points through humans that work in the organization. That is why most external reconnaissance attempts involve hackers trying to reach users through social media, emails, and phone calls. Internal reconnaissance is still a passive attack since the aim is to find information that can be used in future for an even more serious attack.
The main target of internal reconnaissance is the internal network of an organization, where hackers are sure to find the data servers and the IP addresses of hosts they can infect. It is known that data in a network can be read by anyone in the same network with the right tools and skill set. Attackers use networks to discover and analyze potential targets to attack in the future. Internal reconnaissance is used to determine the security mechanisms in place that ward off hacking attempts. There are many cyber security tools that have been made to mitigate software used to perform reconnaissance attacks. However, most organizations never install enough security tools and hackers keep on finding ways to hack through the already-installed ones. There are a number of tools that hackers have tested and have found to be effective at studying their targets' networks. Most of them can be classified as sniffing tools.