Secure Code Review Techniques
Identify security issues in code review: data flows, trust boundaries, dangerous APIs, and missing controls.
Secure Code Review Techniques is a free Cyber Security Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Cyber Security Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
The Goal of Secure Code Review
Secure code review identifies security vulnerabilities in source code before deployment. Unlike functional code review, it focuses on trust boundaries, data flows, dangerous APIs, missing controls, and security logic errors — not correctness or style.
Manual vs Automated Review
Automated SAST tools (Semgrep, SonarQube, CodeQL) catch known patterns quickly but miss business logic flaws, complex multi-component vulnerabilities, and context-dependent issues. Manual review catches what automation misses. Both are necessary.
Entry Point Analysis
Start security review by mapping all entry points: HTTP endpoints, message queue handlers, file uploads, scheduled jobs, webhooks, and CLI arguments. Each entry point that accepts external data is a potential injection point requiring scrutiny.
Data Flow Tracing
Trace user-controlled data from its entry point through the application to its final use. Does it reach a database query? A shell command? An HTML template? An API call? Follow the data flow and check each transformation and sanitization step.
Trust Boundary Analysis
Security decisions happen at trust boundaries — where data moves from a less-trusted context (HTTP request) to a more-trusted one (database, OS). Every trust boundary crossing must validate, sanitize, or authorize the data.
Dangerous API Checklist
Flag uses of: eval(), exec(), system(), shell_exec(), innerHTML, dangerouslySetInnerHTML, deserialize(), pickle.loads(), Runtime.exec(), ProcessBuilder, XML parsers without entity expansion disabled, and cryptographic primitives used directly instead of high-level APIs.
Authentication and Authorization Review
Check: Is every sensitive endpoint protected by authentication? Is authorization checked server-side for every action? Can a user access another user's data by changing an ID parameter (IDOR)? Are sensitive operations protected against CSRF?
Error Handling Review
Look for catch blocks that swallow exceptions silently. Check that error messages shown to users do not reveal internal paths, stack traces, or database structure. Verify that security exceptions (AuthenticationException) are logged and not quietly ignored.
Cryptography Review
Flag: MD5 or SHA-1 for password hashing (use bcrypt/Argon2), hardcoded symmetric keys or IVs, ECB mode encryption (use GCM or CBC with HMAC), custom cryptographic implementations, and random number generators that are not cryptographically secure.
Dependency and Configuration Review
Review package.json/pom.xml for outdated dependencies. Check application configuration for debug mode enabled in production, verbose error pages, admin credentials in config files, and missing security headers (HSTS, CSP, X-Frame-Options).
Tooling: Semgrep and CodeQL
Semgrep rules match syntax patterns with semantic awareness. Write custom rules for your codebase's specific patterns. CodeQL treats code as data — write queries over the AST to find data flows from sources to sinks across files and function calls.
Knowledge Check
What is an IDOR vulnerability and where would you look for it in a code review?
Summary
Effective secure code review combines entry point mapping, data flow tracing, trust boundary analysis, dangerous API detection, and automated SAST tools. It catches security issues that functional review misses, particularly business logic flaws and subtle authorization gaps.
Frequently asked questions
Is the “Secure Code Review Techniques” lesson free?
Yes — the full text of “Secure Code Review Techniques” is free to read here on the web, and the Cyber Security Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Cyber Security Academy course, upgrade to CoddyKit PRO.
What will I learn in “Secure Code Review Techniques”?
Identify security issues in code review: data flows, trust boundaries, dangerous APIs, and missing controls. You practise Cyber Security Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Cyber Security Academy?
No prior experience is required. Cyber Security Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Secure Code Review Techniques” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Cyber Security Academy lesson?
Yes. Every Cyber Security Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.