APIs are the backbone of our modern digital world, connecting everything from your mobile app to your cloud services. But as they've become the primary gateway to our data, they've also become a massive target for cyberattacks. The data is sobering: in 2026, it's estimated that over 90% of web applications will have more attack surface in their APIs than in their user interface.
At Stack Jungle, securing APIs isn't an afterthought—it's a core part of our development process. Let's explore the top 10 API security flaws (inspired by the OWASP API Security Top 10) and the practical steps we take to prevent them.
1. Broken Object Level Authorization (BOLA)
The Flaw: This is the most common and critical API flaw. It happens when an API exposes an endpoint that uses an object's ID (like a user ID) without checking if the person making the request is *allowed* to see that object.
Example: An attacker is logged in as user `123`. They make a request to `/api/user/123/profile` and get their own data. They then simply change the URL to `/api/user/456/profile` and—if BOLA is present—the API will hand over user 456's private information.
How We Prevent It: We enforce object-level checks on *every single request*. We don't just ask "Are you logged in?" We ask, "Are you logged in, *and* does the user ID you're requesting match the user ID in your token?"
2. Broken Authentication
The Flaw: This happens when authentication mechanisms are weak or implemented incorrectly, allowing attackers to impersonate legitimate users.
How We Prevent It: We never roll our own authentication. We use and strictly enforce industry standards like **OAuth 2.0** or **OpenID Connect (OIDC)** with short-lived access tokens (JWTs) and secure refresh tokens. We also implement rate limiting on login endpoints to stop brute-force attacks.
3. Excessive Data Exposure
The Flaw: The API endpoint returns *all* data for an object, including sensitive fields, trusting the frontend to filter it out. An attacker can easily intercept the traffic and see everything.
Example: A user profile request `/api/user/123` returns `{"id": 123, "username": "dennis", "password_hash": "...", "is_admin": false}`. The attacker just found a password hash.
How We Prevent It: We use the "principle of least privilege." Our APIs are designed to return *only* the data necessary for that specific action. We use DTOs (Data Transfer Objects) or server-side filtering to ensure sensitive fields like password hashes or internal flags *never* leave the server.
4. Lack of Rate Limiting & Throttling
The Flaw: An API has no limit on how many requests a client can make. An attacker (or a broken script) can make thousands of requests per second, overwhelming the server and causing a Denial-of-Service (DoS) attack, or use it for brute-force password guessing.
How We Prevent It: We implement strict rate-limiting on all our APIs, usually at the API Gateway level (like AWS API Gateway, NGINX, or in the CodeIgniter app itself). This limits users to a reasonable number of requests (e.g., 100 requests per minute) to ensure service stability for everyone.
5. Broken Function Level Authorization
The Flaw: Similar to BOLA, but for *actions*. The API fails to check if a user has the *permission* to perform a certain action, even if they are authenticated.
Example: A regular user (non-admin) discovers an endpoint like `POST /api/admin/deleteUser`. They are authenticated, so the API lets them call it, and they successfully delete another user.
How We Prevent It: We use **Role-Based Access Control (RBAC)**. Every API endpoint has a rule (e.g., "admin-only," "user-only"), and every user token contains their role. The API checks the user's role against the endpoint's required role before executing any code.
6. Mass Assignment
The Flaw: Modern frameworks make it easy to bind incoming JSON to an internal user object automatically. An attacker can exploit this by "assigning" hidden fields.
Example: A user updates their profile with `{"name": "Attacker"}`. The API maps this to the user model. The attacker then tries `{"name": "Attacker", "is_admin": true}`. If the API is vulnerable, it will "mass assign" the `is_admin` field and promote the attacker to an administrator.
How We Prevent It: We **never** use auto-binding for sensitive models. We explicitly define and whitelist the fields that are allowed to be updated from a request (e.g., `name`, `bio`) and ignore everything else.
7. Security Misconfiguration
The Flaw: A catch-all for common setup errors: verbose error messages that leak data, missing security headers (like HSTS), or overly permissive Cross-Origin Resource Sharing (CORS) policies (e.g., `Allow-Origin: *`).
How We Prevent It: We run a tight ship. We disable verbose errors in production, enforce secure HTTP headers, and lock down CORS to *only* allow requests from our known, trusted domains.
8. Injection Attacks (SQL/Command)
The Flaw: The classic, and it's still here. The API trusts user input and passes it directly into a database query or system command, allowing an attacker to run their own code.
How We Prevent It: We *never* build queries by concatenating strings. We use parameterized queries (prepared statements) or ORMs (like CodeIgniter's) which automatically sanitize all input, making SQL injection impossible.
9. Improper Asset Management
The Flaw: You build `v2` of your API, and it's perfectly secure. But you forget to shut down `v1`, which is still running on a forgotten server and is full of holes. Attackers are constantly scanning for old, unpatched API versions.
How We Prevent It: We maintain a strict API inventory and lifecycle. All API versions are routed through an API Gateway, which allows us to gracefully deprecate and shut down old versions once they are no longer needed.
10. Insufficient Logging & Monitoring
The Flaw: A breach happens, but you have no logs. You can't see how the attacker got in, what data they took, or how to stop them from doing it again.
How We Prevent It: We log all failed login attempts, authorization failures (like BOLA attempts), and high-request volumes. We feed these into a centralized logging system (like AWS CloudWatch or an ELK Stack) with real-time alerting. If someone tries to guess a password 100 times, we know about it *immediately*, not six months later.
Conclusion: Security is a Process, Not a Product
As you can see, API security isn't a single "fix." It's a continuous process of proactive prevention, layered defenses, and vigilant monitoring. By addressing these top flaws, we build APIs that are not just functional, but truly resilient.
At Stack Jungle, we treat your APIs as the first-class citizens they are, ensuring your digital ecosystem is secure, from the inside out.
