OWASP Top 10 Explained Simply: What Every Website Owner Should Know

What Is OWASP?

OWASP (Open Web Application Security Project) is a nonprofit foundation that works to improve software security. Their "Top 10" list is the most widely recognized document on web application security risks.

<div class="zf-stat-callout" style="background:#0d1117;border:1px solid rgba(16,185,129,0.25);border-left:3px solid #10b981;border-radius:4px;padding:16px 20px;margin:24px 0"> <p style="margin:0 0 4px;font-size:10px;font-weight:700;text-transform:uppercase;letter-spacing:0.15em;color:#10b981;font-family:monospace">ZeriFlow Data — 12,400+ sites analyzed</p> <p style="margin:0;font-size:13px;color:#e2e8f0;line-height:1.6;font-family:monospace">In our analysis of 12,400+ sites scanned on ZeriFlow, 64% lack a Content-Security-Policy header — and of those that have one, 71% use 'unsafe-inline', negating XSS protection entirely.</p> </div>

The OWASP Top 10 is updated every few years based on data from hundreds of organizations and thousands of real-world applications. If you run a website, understanding these 10 risks is essential.

The OWASP Top 10 (Current Edition)

1. Broken Access Control

What it is: Users can access data or perform actions they should not be authorized to do.

Real example: A regular user changes the URL from /account/123 to /account/456 and can see another user's data. Or a non-admin user accesses /admin because the server only hides the link but does not check permissions.

How to fix it: - Always check permissions on the server side, not just in the UI - Deny access by default (whitelist approach) - Use role-based access control (RBAC) - Log access control failures and alert on repeated attempts

2. Cryptographic Failures

What it is: Sensitive data is exposed because of weak or missing encryption.

Real example: A website stores passwords in plain text, transmits credit card numbers over HTTP, or uses outdated hashing algorithms like MD5.

How to fix it: - Use HTTPS everywhere (TLS 1.2+) - Hash passwords with bcrypt or argon2 - Encrypt sensitive data at rest - Never store sensitive data you do not need

3. Injection

What it is: Untrusted data is sent to an interpreter as part of a command or query. The most common form is SQL injection.

Real example: An attacker types '; DROP TABLE users; -- into a search field, and the database executes it because the input is not sanitized.

How to fix it: - Use parameterized queries / prepared statements (never concatenate user input into SQL) - Use an ORM (Object-Relational Mapping) - Validate and sanitize all user inputs - Apply the principle of least privilege to database accounts

4. Insecure Design

What it is: The application's architecture has fundamental security flaws that cannot be fixed by implementation alone.

Real example: A password reset flow that sends the actual password via email instead of a one-time reset link. Or a "security question" that asks for publicly available information.

How to fix it: - Threat model during design phase - Use secure design patterns and reference architectures - Create abuse cases alongside use cases - Get security reviews before building

5. Security Misconfiguration

What it is: The application or server is configured with insecure default settings, incomplete configurations, or unnecessary features enabled.

Real example: Default admin credentials left unchanged, directory listing enabled, stack traces shown to users in error pages, unnecessary HTTP methods enabled.

How to fix it: - Remove default accounts and passwords - Disable directory listing - Show generic error pages (never stack traces) - Remove unnecessary features, frameworks, and components - Automate configuration verification with security scanners

6. Vulnerable and Outdated Components

What it is: Using libraries, frameworks, or software with known vulnerabilities.

Real example: Running WordPress 4.x with a known remote code execution vulnerability, or using an npm package with a published CVE.

How to fix it: - Keep all components updated - Remove unused dependencies - Run npm audit, pip audit, or equivalent regularly - Subscribe to security advisories for your tech stack - Use automated dependency scanning in CI/CD

7. Identification and Authentication Failures

What it is: Weaknesses in how users prove who they are.

Real example: Allowing weak passwords like "123456", not implementing rate limiting on login attempts, not supporting multi-factor authentication, or storing session IDs in URLs.

How to fix it: - Enforce strong password policies - Implement multi-factor authentication (MFA) - Rate-limit login attempts - Use secure session management - Never expose session tokens in URLs

8. Software and Data Integrity Failures

What it is: Code or infrastructure that does not verify the integrity of updates, data, or CI/CD pipelines.

Real example: An application auto-updates without verifying the update's digital signature. Or a CI/CD pipeline pulls dependencies without integrity checks, allowing a supply chain attack.

How to fix it: - Verify digital signatures on updates and packages - Use lock files and integrity hashes for dependencies - Secure your CI/CD pipeline - Review code before merging

9. Security Logging and Monitoring Failures

What it is: Not detecting, logging, or alerting on security events.

Real example: An attacker brute-forces login attempts for weeks, but nobody notices because there are no alerts on failed logins. Or a data breach occurs and there are no logs to investigate what happened.

How to fix it: - Log all authentication attempts (success and failure) - Log access control failures - Set up alerts for suspicious patterns - Store logs securely and retain them long enough for investigation - Test your incident response process

10. Server-Side Request Forgery (SSRF)

What it is: The application fetches a remote resource based on user input without validating the destination.

Real example: A URL preview feature that an attacker abuses to access internal services: https://yourapp.com/preview?url=http://169.254.169.254/latest/meta-data/ (AWS metadata endpoint).

How to fix it: - Validate and sanitize all URLs provided by users - Block requests to internal/private IP ranges - Use allowlists for permitted domains - Do not send raw server responses back to users

How to Test for OWASP Top 10

You do not need to be a penetration tester to check for these vulnerabilities:

1. 1Run a security scan — ZeriFlow checks for many OWASP-related issues including check your security headers, SSL configuration, and common misconfigurations
2. 2Review your code — Use static analysis tools (SonarQube, Semgrep)
3. 3Check dependencies — Run npm audit, pip audit, or use Snyk
4. 4Test authentication — Try common attack scenarios manually

Conclusion

The OWASP Top 10 covers the most critical risks, but you do not need to fix everything at once. Start with the basics: update your software, use HTTPS, set security headers, and validate all user input. Then use automated scanning with ZeriFlow to continuously monitor for new issues.

Security is a journey, not a destination.

Further Reading

• RFC 6797 — HTTP Strict Transport Security (HSTS)
• OWASP Top 10 Web Application Security Risks

<!-- zf-internal-links -->