Web Application Security: A Developer's Guide to OWASP Top 10
Security as a Development Practice
Application security is not something a separate team bolts on after development. In modern software engineering, security is embedded into every stage—design, coding, review, and deployment.
The OWASP Top 10 provides a prioritised list of the most critical web application security risks. Here's a developer-friendly breakdown.
The Top 10
1. Broken Access Control
Risk: Users accessing resources or actions they shouldn't be authorised to.
Defence: Default deny, server-side enforcement, and testing with multiple user roles in every sprint.
2. Cryptographic Failures
Risk: Sensitive data exposed due to weak or missing encryption.
Defence: TLS 1.3 for data in transit, AES-256 for data at rest, and never storing passwords in plaintext.
3. Injection
Risk: Malicious input interpreted as code (SQL, NoSQL, OS command).
Defence: Parameterised queries, input validation with allowlists, and proper ORM usage.
4. Insecure Design
Risk: Architecture-level flaws that no amount of code-level fixes can resolve.
Defence: Threat modelling during design and secure design patterns (defence in depth, least privilege).
5. Security Misconfiguration
Risk: Default credentials, open cloud storage buckets, verbose error messages.
Defence: Infrastructure-as-Code with security-hardened templates and automated scanning in CI/CD.
6. Vulnerable Components
Risk: Using libraries or frameworks with known CVEs.
Defence: Automated dependency updates and audit tools in CI pipelines.
7. Authentication Failures
Risk: Weak passwords, credential stuffing, broken session management.
Defence: Multi-factor authentication, rate limiting, and secure cookie configuration.
8. Data Integrity Failures
Risk: Code or data from untrusted sources without integrity verification.
Defence: Subresource Integrity for external scripts and Content Security Policy headers.
9. Logging & Monitoring Failures
Risk: Breaches go undetected because logging is insufficient or not monitored.
Defence: Log authentication events and access control failures, centralise logs, and set up alerts.
10. Server-Side Request Forgery (SSRF)
Risk: Application makes requests to unintended internal or external resources.
Defence: Allowlist permitted URLs, disable unnecessary URL schemes, and network segmentation.
Building a Security Culture
The most effective defence is a team that thinks about security proactively. Conduct threat modelling workshops, include security acceptance criteria in user stories, and celebrate security bug discoveries—not just feature completions.
