Penetration Testing

Penetration testing (pen testing) is an authorized, simulated attack on a computer system, network, or application conducted by security professionals to identify exploitable vulnerabilities before real attackers do.

The tester's objective is identical to a malicious attacker's, i.e., to find weaknesses, attempt to exploit them, and document what was accessed, with the only difference being authorization and intent.

Pen testing is commissioned by the organization being tested. The findings go to the security team, not to a threat actor.

Why penetration testing matters

Security scanners find known vulnerability patterns. Penetration testers find the paths an attacker would actually take: chained vulnerabilities, business logic flaws, and gaps that automated tools are not designed to probe.

A vulnerability assessment tells you what is misconfigured. A penetration test tells you what is actually exploitable and what a real attacker could do with it. Most organizations need both at different stages of their security program.

Types of penetration testing

External penetration testing

Tests the organization's internet-facing systems: web applications, APIs, email servers, and network perimeters. The tester operates from outside the organization's network, simulating an external attacker with no prior access.

Internal penetration testing

Internal penetration testing simulates an attacker who has already gained access to the internal network through a compromised credential, a phishing attack, or physical access. It tests lateral movement, privilege escalation, and access to sensitive internal systems.

Web application penetration testing

Web app pen testing targets web applications specifically: authentication flows, session management, input validation, API endpoints, and access controls. It typically follows the OWASP Top 10 and OWASP Testing Guide.

Mobile application penetration testing

Mobile app pen testing tests iOS and Android apps for vulnerabilities specific to the mobile execution model: insecure data storage, certificate pinning bypass, binary tampering, API authentication flaws, and runtime manipulation. Mobile pen testing requires real physical devices and authenticated test sessions; emulators do not reproduce the full attack surface.

Network penetration testing

Network pen testing assesses network infrastructure, including routers, switches, firewalls, and protocols. It identifies open ports, unpatched services, and misconfigurations that expose internal systems.

Social engineering

Tests the human layer through phishing simulations, pretexting calls, and physical access attempts. It identifies whether security controls are undermined by employee behavior.

Penetration testing approaches

Black box

In black box pen testing, the tester has no prior information about the target. They simulate an external attacker starting from scratch.

White box

In this penetration testing approach, the tester has full access to documentation, source code, and architecture to produce the most thorough coverage. It is used when the goal is a comprehensive security review rather than a realistic attack simulation.

Gray box

In gray box penetration testing, the tester has partial information, typically user-level credentials or high-level architecture documentation. It is the most common approach for application security testing as it balances realism with coverage depth.

Penetration testing vs vulnerability assessment

These two terms are frequently confused. They are different activities.

For the full breakdown, check out: What is a Vulnerability Assessment?

Mobile application penetration testing

Mobile apps introduce vulnerabilities that web and network pen testing may miss. The compiled binary, third-party SDKs, device-specific behaviors, and runtime API call chains all require dedicated mobile security testing.

Appknox's Manual Vulnerability Assessment combines automated binary scanning with hands-on security testing by certified researchers. Findings from both automated and manual testing land in the same developer workflow (Jira, Slack, or GitHub Issues), so remediation is not delayed by a PDF report handed over weeks after testing ends.

For organizations that run continuous release cycles, Appknox integrates manual testing with automated scanning on every build, so the security program moves at the same pace as development.

For a full explanation of how automated and manual pen testing work together, see The Complete Guide to Penetration Testing.

Frequently asked questions

What is the difference between penetration testing and ethical hacking?

Penetration testing is a structured, scoped engagement with defined objectives and a formal report. Ethical hacking is a broader term for authorized offensive security activity, which can include penetration testing but also covers vulnerability research, red team operations, and bug bounty participation. All penetration testing is ethical hacking; not all ethical hacking is penetration testing.

How often should organizations conduct penetration testing?

Most security frameworks recommend annual penetration testing as a baseline, with additional tests triggered by major changes: a new application launch, a significant architecture change, a merger or acquisition, or after a security incident. Regulated industries, including financial services, healthcare, and government, often require penetration testing at defined intervals as part of compliance obligations.

What is the difference between automated scanning and penetration testing?

Automated scanners check for known vulnerability patterns efficiently and at scale. Penetration testers probe for the paths an attacker would actually take:

• Chaining multiple low-severity findings into a high-impact attack,
• Exploiting business logic that no scanner is configured to test, and
• Validating whether vulnerabilities are genuinely exploitable or theoretical.

Both are necessary; neither replaces the other.

What is the difference between penetration testing and red team assessment?

Penetration testing is a scoped, time-boxed engagement with defined targets and a formal deliverable. A red team assessment simulates a full adversary campaign with no predefined scope restrictions, testing the organization's detection and response capabilities alongside its defenses. Penetration testing finds vulnerabilities in a specific system. Red teaming tests whether the organization as a whole can detect and respond to a persistent, skilled adversary.

For the full comparison, see: Penetration Testing vs Red Team.

Does Appknox offer penetration testing for mobile apps?

Yes. Appknox's Manual Vulnerability Assessment is a mobile-specific pen testing service conducted by certified security researchers on real iOS and Android devices. It is available as a standalone engagement and as an integrated component of Appknox's automated security platform, so manual findings appear in the same workflow as automated scan results.

How this page was produced: Content written by Appknox's certified security research team, reviewed against OWASP MASVS, PTES, and NIST SP 800-115 penetration testing guidance. No vendor provided sponsorship or editorial input.

Related:  What is MAST? | What is Vulnerability Assessment? | Mobile Application Penetration Testing | The Complete Penetration Testing Guide

By Abhinav Vasisth, Security Research Lead, Appknox

Appknox is an enterprise mobile application security testing platform. This page was written by Appknox's certified security research team based on direct experience conducting mobile application penetration testing engagements across financial services, healthcare, and enterprise organizations.

This page was drafted with AI assistance and reviewed and verified by the Appknox security research team.