Securing REST & GraphQL APIs: OWASP Top 10 API Vulnerabilities

Securing REST & GraphQL APIs: OWASP Top 10 API Vulnerabilities

APIs serve as the connectivity layer for modern web applications, routing data between client frontends, databases, and third-party services. Consequently, they are a primary target for attackers.

Let's look at the top API vulnerabilities and how to address them.

1. Broken Object Level Authorization (BOLA / IDOR) BOLA occurs when an endpoint accepts user-supplied identifiers (such as UUIDs or sequential IDs) to access resource models without validating that the logged-in user owns the requested resource.

Mitigation: Implement object-level authorization checks in your controllers: ```javascript const resource = await Database.getResource(req.params.id); if (resource.userId !== req.user.id) { return res.status(403).send("Unauthorized Access"); } ```

2. Broken Object Property Level Authorization (Mass Assignment) This vulnerability occurs when endpoints allow users to modify database properties they shouldn't access (such as setting an `isAdmin: true` flag) by submitting unexpected JSON parameters.

Mitigation: Enforce input validation using transfer schemas or select parameters explicitly: ```javascript const safePayload = { username: req.body.username, bio: req.body.bio }; await User.update(req.user.id, safePayload); ```