An Ethical Hacker is someone who specialises in computer security through what’s known as “Penetration Testing”, which are series of exercises carried out against computer systems to spot vulnerabilities and weaknesses.
Ethical hacking is generally divided into five steps, each of which to be performed one after the other. This is the methodology most penetration testing professionals apply.
This is the first phase of the process, and involves gathering information about the target passively. For example, using Shodan, visiting the company website to understand their network infrastructure and employee hierarchy, searching Twitter for official accounts and more. In this stage, the hacker does not interact directly with the company systems, but simply uses OSINT, or Open Source INTelligence.
After Reconnaissance has been executed, it’s time for the scanning phase. The scanning phase involves interacting and communicating directly with the company’s servers with tools like Nmap, Nikto or Nessus, to get a deeper understanding of the network topology, open ports, software versions, hidden directories and vulnerabilities present in the systems.
Once the ethical hacker understands all the weaknesses and entry points in a network, they can launch an attack in order to obtain privileged access into the system, for whatever purpose they need. They might want to use the first attack to pivot to a different server, or they might want to get root access to an HTTP server running inside the company’s LAN, or just dump databases from an unprotected PostgreSQL server.
To ensure the success of the operation and be able to exfiltrate as much data as possible the attacker will want to create a form of persistence in the affected systems, be it through Unix crontabs, Windows task schedulers, daemons, modifying legitimate binaries, and more. To this end, the attacker will have to remain stealthy because modifying a target system will often leave a trace that can be spotted by network and system administrators.
The final step is reverting changes to leave as little trace as possible, such as deleting logs, re-enabling security measures, and deleting temporary files that aided in the attack. This will help the attacker stay in the network for as long as they want, while ensuring nobody suspects they’ve been attacked.