A Penetration Tester (also called a pen tester or ethical hacker) is a security professional who simulates real-world cyberattacks against systems, networks, and applications to identify vulnerabilities before malicious actors exploit them. Pen testers use a combination of automated tools and manual techniques to probe for weaknesses in an organization's defenses. They conduct reconnaissance, identify attack surfaces, attempt exploitation, escalate privileges, pivot through networks, and document their findings in detailed reports with remediation recommendations. The role requires deep technical knowledge across operating systems, networking, web technologies, and scripting, combined with creative problem-solving and persistence.
Penetration testing engagements follow a structured methodology. The tester begins with scoping and rules of engagement, then moves through reconnaissance, vulnerability scanning, exploitation, post-exploitation, and reporting. Common tools include Burp Suite, Nmap, Metasploit, BloodHound, Cobalt Strike, and custom scripts. Pen testers may specialize in network penetration testing, web application testing, mobile application testing, cloud security testing, or social engineering. Red team operations extend pen testing into full adversary simulation with longer timeframes and broader scope. Career entry typically comes through Security+, followed by CEH or eJPT, with OSCP being the key differentiator for serious practitioners. Senior pen testers may pursue OSCE3, GXPN, or CREST certifications.
Penetration testing is one of the most in-demand and well-compensated specializations in cybersecurity. Organizations need pen testers to validate their defenses, meet compliance requirements, and identify critical vulnerabilities before attackers do. The role offers variety, intellectual challenge, and the satisfaction of thinking like an adversary to protect organizations. Pen testers can work in-house, for consulting firms, or as independent contractors. The skills translate directly into red team, purple team, and security research roles. Experienced pen testers who develop leadership skills often progress to Offensive Security Lead, Red Team Manager, or Security Director positions.