What is penetration testing and what are its different phases?

Penetration testing (pen testing) is a simulated cyberattack against systems to identify vulnerabilities that could be exploited by malicious actors.\n\n**Why penetration testing is important:**\n• **Proactive security** - Find vulnerabilities before attackers do\n• **Compliance requirements** - Meet regulatory standards (PCI DSS, SOX)\n• **Risk assessment** - Understand real-world security posture\n• **Security validation** - Test effectiveness of security controls\n\n**Penetration testing phases:**\n\n**1. Planning and reconnaissance:**\n• **Scope definition** - Determine systems, networks, and applications to test\n• **Rules of engagement** - Establish testing boundaries and limitations\n• **Information gathering** - Collect publicly available information (OSINT)\n• **Tools used** - Google dorking, Shodan, social media research\n• **Example** - Gathering employee emails, technology stack, network ranges\n\n**2. Scanning and enumeration:**\n• **Network discovery** - Identify live hosts and open ports\n• **Service identification** - Determine running services and versions\n• **Vulnerability scanning** - Use automated tools to find known vulnerabilities\n• **Tools used** - Nmap, Nessus, OpenVAS, Burp Suite\n• **Example** - Finding open SSH on port 22 with outdated version\n\n**3. Gaining access (exploitation):**\n• **Vulnerability exploitation** - Attempt to exploit identified weaknesses\n• **Privilege escalation** - Gain higher-level access once inside\n• **Lateral movement** - Move through network to access additional systems\n• **Tools used** - Metasploit, custom exploits, social engineering\n• **Example** - Exploiting SQL injection to access database\n\n**4. Maintaining access:**\n• **Persistence** - Establish ongoing access to compromised systems\n• **Backdoor creation** - Install tools for future access\n• **Data exfiltration** - Simulate theft of sensitive information\n• **Example** - Installing remote access trojan (RAT)\n\n**5. Analysis and reporting:**\n• **Documentation** - Record all findings and exploitation methods\n• **Risk assessment** - Prioritize vulnerabilities by impact and likelihood\n• **Remediation recommendations** - Provide specific fix instructions\n• **Executive summary** - High-level overview for management\n\n**Types of penetration testing:**\n• **Black box** - No prior knowledge of systems\n• **White box** - Full knowledge of infrastructure\n• **Gray box** - Limited knowledge (typical employee level)