Here’s What You Need to Know About Penetration Testing

Penetration testing refers to the process where cybersecurity professionals simulate attacks against networks or computer systems to assess security, with full authorization from system owners. Though these are simulated attacks, penetration testers deploy the exact tools and techniques used by real-world threat actors on target systems. Unlike malicious attackers, they do not exploit discovered vulnerabilities or stolen data for profit; instead, they submit findings to asset owners to help strengthen system security.

Since penetration testers adopt identical attack strategies as malicious hackers, they are often called ethical hackers or white hat hackers. Penetration testing can be performed by dedicated teams or individual specialists, who may be internal staff of the target enterprise, independent practitioners, or employees of cybersecurity firms offering professional penetration testing services.

Broadly speaking, penetration testing replicates the full attack workflow of real adversaries seeking to compromise an organization's systems. Testers first enumerate and identify hosts, ports and network services associated with the target. Next, they dig deep into potential vulnerabilities across the attack surface through intensive probing. Finally, they attempt to bypass security perimeters to access sensitive protected data or gain system control.

Testers must agree with the target organization in advance on the exact test types and scope of simulated intrusions, to avoid irreversible damage to production systems.

Types of Penetration Testing

External Penetration Testing

Testing teams evaluate the target network infrastructure from remote locations with zero prior knowledge of internal network topology, fully mimicking external attackers in real online environments. Using mainstream attack tools and techniques, testers launch structured, step-by-step intrusions to expose known and unknown security flaws, and assess whether such vulnerabilities can be exploited to seize system control or cause losses to business assets.

Internal Penetration Testing

Teams conducting internal testing have full visibility into the target's internal infrastructure and underlying architecture, enabling them to detect and validate high-severity vulnerabilities with minimal effort. This test simulates intrusion scenarios triggered by disgruntled employees, malicious contractors or rogue privileged attackers.

Blind Test

A blind test replicates authentic external attacks. Testers receive no pre-shared data about the organization's networks or systems and must rely solely on public open-source intelligence or self-collected information through reconnaissance.

Double-Blind Test

This test also simulates real-world intrusions, yet the organization's IT and security teams are not notified of the ongoing penetration test. This setup delivers an authentic snapshot of the enterprise's actual security posture.

Targeted Testing

Also known as lights-on testing, targeted testing creates a simulated adversarial engagement between penetration testers and the client's IT team, focusing on specific segments of network infrastructure under defined scenarios. It consumes less time and resources than other test variants but fails to deliver a holistic view of overall system security.

Standard Penetration Testing Workflow

While each testing type has unique characteristics, the Penetration Testing Execution Standard (PTES) formulated by industry experts outlines seven core stages applicable to most penetration testing engagements:

1. Pre-Engagement Interactions

All penetration testing requires formal pre-agreement between testers and the target organization to define the test scope and objectives, preferably documented in writing.

2. Intelligence Gathering

Testers conduct reconnaissance to collect maximum available information about the target, primarily through open-source intelligence collection.

3. Threat Modeling

Testers model the capabilities and motives of potential real attackers, and identify high-value assets within the organization that may attract threat actors.

4. Vulnerability Analysis

This is the core phase of formal penetration testing: scanning the organization's infrastructure to detect security vulnerabilities that could enable unauthorized access.

5. Vulnerability Exploitation

Testers leverage identified vulnerabilities to infiltrate target systems and extract sensitive data. The goal is not merely crossing security boundaries, but evading active defense systems and maintaining undetected access for as long as possible.

6. Post-Exploitation

Testers seek persistent control over compromised assets and evaluate their business impact. This stage carries high operational risks for both testers and clients. Clear ground rules defined during pre-engagement are critical to protect the client and prevent disruptions to core business services.

7. Reporting

Upon test completion, testers deliver a comprehensive, detailed report to the client documenting all identified risks and vulnerabilities.