OWASP Security Check

Comprehensive security audit patterns for web applications and REST APIs. Contains 20 rules across 5 categories covering OWASP Top 10 and common web vulnerabilities.

When to Apply

Use this skill when:

• Auditing a codebase for security vulnerabilities
• Reviewing user-provided file or folder for security issues
• Checking authentication/authorization implementations
• Evaluating REST API security
• Assessing data protection measures
• Reviewing configuration and deployment settings
• Before production deployment
• After adding new features that handle sensitive data

How to Use This Skill

1. Identify application type - Web app, REST API, SPA, SSR, or mixed
2. Scan by priority - Start with CRITICAL rules, then HIGH, then MEDIUM
3. Review relevant rule files - Load specific rules from @rules/ directory
4. Report findings - Note severity, file location, and impact
5. Provide remediation - Give concrete code examples for fixes

Audit Workflow

Step 1: Systematic Review by Priority

Work through categories by priority:

1. CRITICAL: Authentication & Authorization, Data Protection, Input/Output Security
2. HIGH: Configuration & Headers
3. MEDIUM: API & Monitoring

Step 2: Generate Report

Format findings as:

• Severity: CRITICAL | HIGH | MEDIUM | LOW
• Category: Rule name
• File: Path and line number
• Issue: What's wrong
• Impact: Security consequence
• Fix: Code example of remediation

Rules Summary

Authentication & Authorization (CRITICAL)

broken-access-control - @rules/broken-access-control.md

Check for missing authorization, IDOR, privilege escalation.

// Bad: No authorization check
async function getUser(req: Request): Promise<Response> {
  let url = new URL(req.url);
  let userId = url.searchParams.get("id");
  let user = await db.user.findUnique({ where: { id: userId } });
  return new Response(JSON.stringify(user));
}

// Good: Verify ownership
async function getUser(req: Request): Promise<Response> {
  let session = await getSession(req);
  let url = new URL(req.url);
  let userId = url.searchParams.get("id");

  if (session.userId !== userId && !session.isAdmin) {
    return new Response("Forbidden", { status: 403 });
  }

  let user = await db.user.findUnique({ where: { id: userId } });
  return new Response(JSON.stringify(user));
}

authentication-failures - @rules/authentication-failures.md

Check for weak authentication, missing MFA, session issues.

// Bad: Weak password check
if (password.length >= 6) {
  /* allow */
}

// Good: Strong password requirements
function validatePassword(password: string) {
  if (password.length < 12) return false;
  if (!/[A-Z]/.test(password)) return false;
  if (!/[a-z]/.test(password)) return false;
  if (!/[0-9]/.test(password)) return false;
  if (!/[^A-Za-z0-9]/.test(password)) return false;
  return true;
}

Data Protection (CRITICAL)

cryptographic-failures - @rules/cryptographic-failures.md

Check for weak encryption, plaintext storage, bad hashing.

// Bad: MD5 for passwords
let hash = crypto.createHash("md5").update(password).digest("hex");

// Good: bcrypt with salt
let hash = await bcrypt(password, 12);

sensitive-data-exposure - @rules/sensitive-data-exposure.md

Check for PII in logs/responses, error messages leaking info.

// Bad: Exposing sensitive data
return new Response(JSON.stringify(user)); // Contains password hash, email, etc.

// Good: Return only needed fields
return new Response(
  JSON.stringify({
    id: user.id,
    username: user.username,
    displayName: user.displayName,
  }),
);

data-integrity-failures - @rules/data-integrity-failures.md

Check for unsigned data, insecure deserialization.

// Bad: Trusting unsigned JWT
let decoded = JSON.parse(atob(token.split(".")[1]));
if (decoded.isAdmin) {
  /* grant access */
}

// Good: Verify signature
let payload = await verifyJWT(token, secret);

secrets-management - @rules/secrets-management.md

Check for hardcoded secrets, exposed env vars.

// Bad: Hardcoded secret
const API_KEY = "sk_live_a1b2c3d4e5f6";

// Good: Environment variables
let API_KEY = process.env.API_KEY;
if (!API_KEY) throw new Error("API_KEY not configured");

Input/Output Security (CRITICAL)

injection-attacks - @rules/injection-attacks.md

Check for SQL, XSS, NoSQL, Command, Path Traversal injection.

// Bad: SQL injection
let query = `SELECT * FROM users WHERE email = '${email}'`;

// Good: Parameterized query
let user = await db.user.findUnique({ where: { email } });

ssrf-attacks - @rules/ssrf-attacks.md

Check for unvalidated URLs, internal network access.