The OWASP Top 10 is the most referenced framework in web application security. If you hire a penetration tester, they will test against it. If you build a web application, your developers should know it. Here is what each vulnerability category means in plain English.

What Is OWASP?

OWASP (Open Worldwide Application Security Project) is a nonprofit that produces open-source security standards and guidance. The Top 10 is their list of the most critical web application security risks, updated every few years based on real-world breach data.

When Blackhount says we conduct OWASP-based penetration testing, we mean we systematically test your application against every category on this list.

A01: Broken Access Control

This is the most common critical finding in web applications. Access control means the rules about who can see or do what. Broken access control means those rules are not properly enforced.

Real example: A customer portal shows your account at /account/1234. Change the URL to /account/1235 and you see someone else's account. The application never checked whether you were authorized to view that record. We find this in roughly 40% of the web applications we test.

A02: Cryptographic Failures

Sensitive data (passwords, credit card numbers, health records) should be encrypted in transit and at rest. Cryptographic failures happen when data is transmitted without HTTPS, stored without encryption, or encrypted with weak, outdated algorithms.

The most common form we see: passwords stored as plain text or using MD5, an algorithm that was broken decades ago. If your database is breached, plain-text passwords expose every account immediately.

A03: Injection

SQL injection is the classic example. An attacker types malicious code into a form field that gets executed by your database. Instead of searching for a username, the database executes the attacker's commands: dump every user record, delete tables, create new admin accounts.

Injection vulnerabilities have been around for 25 years and are still found regularly. They exist when applications do not properly separate code from data in user input.

A04: Insecure Design

This category covers flaws in the logic of how an application is designed, not just how it is coded. A password reset flow that lets you reset any account by guessing a weak token. A checkout process that can be manipulated to pay less than the listed price. These are design problems, not implementation bugs.

A05: Security Misconfiguration

Cloud storage buckets set to public. Default admin credentials left unchanged. Error messages that reveal your technology stack and version numbers to attackers. Debug features left enabled in production. All of these are misconfigurations and all of them are common.

A06: Vulnerable and Outdated Components

Your application uses third-party libraries, frameworks, and plugins. When vulnerabilities are discovered in those components and you have not updated them, you are exposed. The 2017 Equifax breach that exposed 147 million people happened because of an unpatched Apache Struts vulnerability that had a public fix available for two months.

A07: Identification and Authentication Failures

Weak password requirements. No account lockout after repeated failed login attempts. Session tokens that do not expire. MFA that can be bypassed. These failures allow attackers to compromise accounts through brute force, credential stuffing, or session hijacking.

A08: Software and Data Integrity Failures

Applications that pull updates or plugins from external sources without verifying their integrity. Supply chain attacks that inject malicious code through a trusted dependency. This is how the SolarWinds attack compromised thousands of organizations.

A09: Security Logging and Monitoring Failures

You cannot respond to an attack you cannot see. Insufficient logging means attacks go undetected for months. The average time to detect a breach in a small business is still measured in months, not hours. Proper logging and alerting is not glamorous security work but it is what limits the damage when something happens.

A10: Server-Side Request Forgery (SSRF)

This vulnerability tricks a server into making requests to internal systems on behalf of the attacker. In cloud environments, this can expose infrastructure metadata, credentials, and internal services that should never be reachable from the internet.

What This Means for Your Business

If you have a web application that handles customer data, logins, or payments, it should be tested against the full OWASP Top 10. Automated scanners catch some of these. A manual penetration test catches all of them, including the business logic issues that no scanner can find.

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