Penetration testing is a type of software testing where skilled security professionals attempt to breach an organization’s systems and networks to identify vulnerabilities before malicious actors can exploit them.

This methodical process involves simulating real-world attack scenarios using the same tools and techniques employed by hackers, with the critical difference being permission and purpose – pen testers operate with explicit authorization and aim to strengthen security rather than compromise it.

Why perform penetration testing?

Penetration testing is a structured security assessment where authorized security professionals actively probe systems for exploitable vulnerabilities. Unlike automated vulnerability testing, penetration tests involve human expertise to analyze systems, identify potential attack vectors, and exploit weaknesses using methods similar to those of actual attackers.

These tests vary in scope from targeted application testing to comprehensive network assessments, and can be conducted with different levels of prior knowledge—from “black box” approaches where testers have no inside information to “white box” scenarios with complete system documentation access.

The primary objective of penetration testing is risk identification and mitigation before a real attack occurs. Organizations conduct these tests to validate security controls, meet compliance requirements like PCI DSS or HIPAA, protect sensitive data, and demonstrate security due diligence to stakeholders.

Well-executed penetration tests provide concrete evidence of security gaps, prioritized by severity and exploitability, enabling security teams to allocate resources effectively. Beyond identifying technical vulnerabilities, these tests often reveal process weaknesses, such as inadequate patch management or insufficient security monitoring, providing a comprehensive view of an organization’s security posture.

How is penetration testing performed?

Penetration testing follows a methodical process regardless of the target environment.

Teams begin with reconnaissance, gathering information about the target through public sources, network scanning, and enumeration techniques to map attack surfaces.

They then move to vulnerability analysis, identifying potential weaknesses through both automated tools and manual investigation.

The exploitation phase follows, where testers attempt to leverage discovered vulnerabilities to gain access to systems or data. After successful exploitation, testers may perform privilege escalation and lateral movement to determine how far an attacker could penetrate.

The process concludes with documentation of findings, including technical details of vulnerabilities, evidence of exploitation, and remediation recommendations.

How much access do penetration testers need?

Determining the appropriate level of access for penetration testers depends on the test objectives and the security maturity of the organization. Testing methodologies typically fall along a spectrum from black box (no prior information) to white box (complete system knowledge).

Black box testing simulates an external attacker with no inside knowledge, providing realistic results but potentially missing critical vulnerabilities due to limited time and scope.

White box testing grants testers full access to documentation, source code, and architecture diagrams, enabling more comprehensive vulnerability discovery but less accurately representing real-world attack scenarios.

Most organizations benefit from a gray box approach, where testers receive partial information such as network diagrams or user-level access. This balanced methodology offers the efficiency of white box testing while maintaining some elements of realistic attack simulation.

For organizations new to penetration testing, starting with greater tester access often yields more valuable results by uncovering a broader range of vulnerabilities. As security matures, gradually restricting tester access in subsequent assessments helps evaluate security effectiveness against more sophisticated threats.

Regardless of the approach, clearly defining test boundaries in writing—including systems in scope, permitted techniques, and emergency contacts—remains essential to prevent unintended disruption and ensure alignment with business objectives.

Types of penetration testing

Different types of penetration testing serve various security objectives.

• Network penetration testing targets infrastructure components like firewalls, routers, and servers to identify network-level vulnerabilities. Testers probe for open ports, misconfigured services, and unpatched systems that could provide unauthorized network access. This testing often includes both internal and external network assessments to evaluate perimeter defenses and internal segmentation.
• Web application testing focuses on uncovering flaws in web applications such as SQL injection, cross-site scripting, and authentication weaknesses. Testers scrutinize input validation, session management, and access controls to identify ways attackers might manipulate applications to access sensitive data or gain unauthorized privileges.
• Mobile application testing addresses platform-specific vulnerabilities in iOS and Android apps. This includes examining insecure data storage, weak cryptographic implementations, and flawed client-side validation. Testers also evaluate how apps interact with backend services and handle sensitive information on mobile devices.
• Social engineering tests evaluate human susceptibility to manipulation through phishing, pretexting, or physical security breaches. These tests assess whether employees follow security policies and recognize manipulation attempts. Results often indicate the need for improved security awareness training and process adjustments.
• Wireless network testing assesses the security of WiFi infrastructure and connected devices. Testers evaluate encryption standards, authentication mechanisms, and rogue access point detection capabilities. This testing identifies wireless networks that could provide attackers with an entry point to the broader network.
• Cloud penetration testing examines cloud environments for misconfigurations and access control issues. This includes evaluating identity management, resource permissions, and shared responsibility model implementation. Testing adapts to the specific cloud service models in use (IaaS, PaaS, SaaS).
• Red team exercises provide the most comprehensive assessment by simulating persistent, targeted attacks across multiple vectors simultaneously, often without the knowledge of internal security teams. These exercises test both technical controls and incident response capabilities through realistic attack scenarios sustained over extended periods.

Benefits of penetration testing

Penetration testing provides organizations with actionable intelligence to strengthen their security posture before a real attack occurs. By identifying vulnerabilities and their potential impact, these assessments enable security teams to allocate resources efficiently toward the most critical weaknesses.

This proactive approach significantly reduces the risk of successful breaches and the associated costs, which can include financial losses, regulatory penalties, and reputational damage that often far exceed the investment in testing.

Beyond technical findings, penetration testing validates the effectiveness of existing security controls and identifies process gaps that may not be evident through automated scanning alone. This comprehensive evaluation helps organizations build layered defenses that address both technological and human factors in security.

The detailed reporting from penetration tests also helps bridge communication gaps between technical teams and executive leadership by translating complex vulnerabilities into business risk terms that drive informed decision-making.

Regulatory compliance often requires regular security assessments, making penetration testing a necessary component of many security programs. Industries handling sensitive data, such as healthcare, finance, and government sectors, face particularly stringent requirements. By maintaining a consistent penetration testing schedule, organizations demonstrate due diligence to regulators, customers, and partners, establishing trust that security is taken seriously. This documented commitment to security can become a competitive advantage when security consciousness increasingly influences business relationships.

Challenges of penetration testing

Penetration testing faces significant scope and time constraints that can limit effectiveness. Organizations often restrict testing to specific systems or networks, potentially missing vulnerabilities at intersection points between tested and untested environments. Time limitations further compound this issue, as testers must prioritize likely attack vectors rather than conducting exhaustive examinations. These constraints create blind spots where vulnerabilities may remain undetected despite testing efforts.

False positives and negatives present another challenge. Automated tools often flag potential vulnerabilities that turn out to be harmless upon manual verification, creating unnecessary work. More concerning are false negatives—actual vulnerabilities that testing fails to identify. This risk increases when testers lack specialized knowledge of particular systems or when novel attack techniques emerge. Organizations must recognize that even thorough penetration testing provides a point-in-time assessment rather than ongoing security assurance.

Testing production environments introduces operational risks that require careful management. Aggressive testing techniques can trigger unexpected system behavior, from performance degradation to complete service outages. While testing in development environments reduces this risk, it may not accurately reflect production conditions. Additionally, organizations often struggle to remediate discovered vulnerabilities promptly due to resource constraints, competing priorities, or dependencies on third-party vendors. This remediation gap can leave known vulnerabilities exposed despite identification through testing.

Penetration testing tools

Security professionals rely on specialized tools to efficiently discover and exploit vulnerabilities during penetration tests, with the following representing some of the most widely used options in the industry:

• Metasploit Framework - A comprehensive exploitation platform providing tools for vulnerability discovery, payload development, and post-exploitation.
• Burp Suite - An integrated platform for web application security testing with capabilities for mapping, analyzing, and attacking web applications.
• Wireshark - A network protocol analyzer for examining network traffic at a granular level, helping identify suspicious communications and security issues.
• Nmap - A powerful network discovery and security auditing utility used for port scanning, host discovery, and service/OS detection.
• OWASP ZAP - An open-source web application security scanner for finding vulnerabilities in web applications.
• Kali Linux - A security-focused Linux distribution with hundreds of pre-installed penetration testing tools.
• John the Ripper - A password cracking tool that detects weak passwords in systems.
• Aircrack-ng - A suite of tools for assessing WiFi network security through monitoring, attacking, and testing.
• Sqlmap - An open-source tool that automates the detection and exploitation of SQL injection vulnerabilities.

Penetration testing with CI/CD

Integrating penetration testing into Continuous Integration/Continuous Delivery(CI/CD) pipelines transforms security from a periodic assessment to an ongoing verification process.

This shift-left approach identifies vulnerabilities earlier in the development lifecycle when remediation costs significantly less than post-deployment fixes. By incorporating Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST) tools into automated workflows, organizations enable continuous security validation throughout development.

SAST analyzes source code without execution to identify coding flaws, while DAST tests running applications to discover runtime vulnerabilities that might elude static analysis. These automated checks serve as a first line of defense, allowing human penetration testers to focus their expertise on complex vulnerabilities requiring advanced analysis.

CircleCI provides an effective platform for implementing security-focused CI/CD pipelines that complement manual penetration testing efforts.

Security teams can configure CircleCI to run SAST tools during build processes and trigger DAST scans against staging environments before promotion to production. This automation ensures consistent application of security checks across all code changes while maintaining detailed audit trails of testing activities.

Through CircleCI’s orchestration capabilities, organizations can establish gates that prevent vulnerable code from advancing to production, effectively enforcing security standards throughout the development process. This continuous security validation approach helps organizations maintain robust security postures despite rapid deployment cycles, bridging the traditional gap between development speed and security thoroughness.

Conclusion

Penetration testing provides a critical security evaluation where skilled professionals simulate real-world attacks to identify vulnerabilities before malicious actors can exploit them. Through methodical assessment of applications, networks, and systems, organizations gain actionable intelligence to strengthen their security posture. This controlled offensive approach reveals both technical weaknesses and process gaps that might otherwise remain undiscovered until an actual breach occurs.

Combining penetration testing with CI/CD pipelines through platforms like CircleCI transforms security from a periodic checkpoint to a continuous validation process. This integration embeds security scanning directly into development workflows, enabling early vulnerability detection when remediation is less costly and disruptive.

Human penetration testers can then focus their expertise on sophisticated vulnerabilities that automated tools might miss, creating a comprehensive security approach that maintains pace with rapid development cycles.

Take the first step toward building more secure applications by integrating security testing into your development process. Sign up for a free CircleCI account today to explore how automated security scanning can complement your penetration testing efforts and strengthen your overall security program.