OWASP Top 10: The Most Critical Web-based Vulnerabilities
In web development, alongside functionality and design, the most critical aspect is Security. As soon as you publish a website on the internet, thousands of automated bots start scanning it, looking for open doors and vulnerabilities. OWASP (Open Worldwide Application Security Project) is a non-profit organization that regularly publishes its "Top 10" list. This list summarizes the most dangerous security flaws threatening web applications.
Let's look at the most well-known vulnerabilities and how to prevent them based on recent reports!
1. Injection - SQL Injection
Injection occurs when a malicious user sends data to the application that alters the command to be executed by the server. The most famous example is SQL Injection. If you insert the password received from the user into the SQL query without verification, the attacker can type code (e.g., ' OR '1'='1) that exposes all the records in the database.
Prevention: Never manually concatenate SQL strings! Use Parameterized queries (Prepared Statements) or an ORM system (e.g., Prisma, Sequelize) that automatically "sanitizes" the input.
2. Broken Authentication
This category includes poorly implemented login functions, allowing easily guessable, weak passwords, improperly protected Session identifiers, or the lack of login rate limiting (allowing Brute Force password-cracking attacks).
Prevention: Implement Multi-Factor Authentication (MFA). Demand strong passwords. Use slow password-hashing algorithms (e.g., bcrypt, Argon2). Lock the account after a few unsuccessful attempts.
3. Cross-Site Scripting (XSS)
XSS happens when an attacker manages to smuggle JavaScript code onto your website, which the browsers of other, innocent users then execute unknowingly. Imagine a forum where the attacker submits a <script> tag instead of plain text in a comment, which then steals the readers' Cookies.
Prevention: All content coming from the user must be encoded (escaped/sanitized) before being displayed in HTML. Modern frontend frameworks (like React or Angular) protect against most XSS by default because they treat variables as text, not as executable HTML.
4. Insecure Direct Object References (IDOR)
An IDOR vulnerability occurs if an application grants access to an object purely based on a parameter (e.g., an ID in the URL) without checking permissions. For example, if I log in and access my profile at the /api/profile/100 URL, what happens if I manually rewrite the URL to /api/profile/101? If the server does not verify that I am authorized to see user 101's data, then we are dealing with an IDOR flaw.
Prevention: For every single database query, the backend must verify, based on the current session (Token), whether the active user actually has the right to read or modify the requested resource.
Summary
Web security is not a "set it and forget it" process, but a continuous cat-and-mouse game with attackers. Knowing the OWASP Top 10 list is the absolute minimum for every web developer. Never trust client-side (in-browser) validations, as they are easily bypassed! True security is always decided on the server (Backend).
Frequently Asked Questions (FAQ)
What is the difference between XSS and SQL Injection?
Both are injection attacks, but their targets are different. SQL Injection attacks the database server itself, stealing or destroying data. XSS, on the other hand, targets the browsers of other users to steal their passwords or sessions.