OWASP top ten for beginners

Understanding web security is essential for anyone working with digital technologies today. Whether you’re aspiring to become a developer, already building web applications, or simply interested in how the internet keeps your data safe, the OWASP Top Ten offers a practical roadmap. The Open Web Application Security Project (OWASP) regularly publishes a list of the ten most critical web application security risks, drawn from real-world data and expert consensus. This guide will introduce you to each vulnerability on the current OWASP Top Ten, explain what it means, and offer illustrative examples to deepen your understanding.

1. Broken Access Control

Access control refers to the ways an application restricts what users can see or do. When these controls are improperly implemented, attackers may access data or functions outside their intended permissions.

Consider a web app where normal users should not access the admin panel. If the URL /admin is not guarded by proper authentication checks, a curious user could simply type the address and gain unauthorized access. This is more common than you might expect, particularly in legacy or hastily built systems.

Tip: Always verify user roles on the server side, not just via hidden UI elements or client-side JavaScript.

Common Examples

• Changing a user ID in the URL to view another user’s information
• Accessing admin functions without proper authentication
• Modifying parameters to escalate privileges

2. Cryptographic Failures

Previously known as “Sensitive Data Exposure,” this risk highlights failures to protect data in transit or at rest. Cryptography is not just for spies and secret agents – it’s the backbone of trust on the web.

Imagine a login form that submits credentials over HTTP instead of HTTPS. Anyone between your browser and the server could easily intercept your username and password. Similarly, storing sensitive information like credit card numbers in plain text on the server leaves users vulnerable if there’s a breach.

Encryption should be used everywhere sensitive data is handled. When in doubt, encrypt.

3. Injection

Injection attacks occur when untrusted data is sent as part of a command or query. The classic example is SQL injection, but injection can impact any interpreter, such as NoSQL, LDAP, or even operating system commands.

Suppose a search box on your site passes user input directly into a database query. An attacker might submit input like ‘ OR ‘1’=‘1 to trick the database into returning more data than intended, or even to manipulate or destroy data.

Why is it so common?

Because developers often trust that user input will be benign, or they don’t know how to properly sanitize input. Using prepared statements and parameterized queries helps prevent most injection vulnerabilities.

4. Insecure Design

This relatively new category addresses flaws in the very design of an application, not just in its implementation. Security should be considered from the start, not bolted on as an afterthought.

For example, a web app that allows users to upload files but fails to restrict the file types or size could be exploited to upload malicious scripts. Or, a system might lack proper rate limiting, allowing attackers to brute-force passwords at will.

Building security into the design phase is not just best practice – it’s essential for long-term resilience.

5. Security Misconfiguration

Configuration errors are among the most prevalent vulnerabilities. This includes default credentials, unnecessary services running, overly verbose error messages, or simply forgetting to disable debugging features in production.

Imagine deploying an application with the default admin password still set. Or, a server revealing its software version and stack details in error messages, giving attackers valuable information.

Regular audits and automated configuration management can reduce these risks dramatically.

6. Vulnerable and Outdated Components

Modern web apps rely on countless libraries and frameworks. Using components with known vulnerabilities is like building a house with rotten wood – it might look fine, but it’s structurally unsound.

Suppose your site uses an old version of a JavaScript library that has a well-documented security flaw. Attackers can easily find out which version you’re using and tailor their attacks accordingly.

Automated tools can help regularly scan dependencies for vulnerabilities. Don’t leave it to chance.

7. Identification and Authentication Failures

Authentication is the process of verifying who someone is. Authorization is about what they’re allowed to do. Both are critical, but authentication failures are particularly dangerous.

Weak passwords, predictable login URLs, lack of multi-factor authentication, or insecure session management can all result in attackers impersonating users.

Real-World Example

Some sites implement a “forgot password” feature that doesn’t properly verify the user’s identity, allowing attackers to reset passwords with minimal information. Or, session tokens are not invalidated after logout, enabling session hijacking.

8. Software and Data Integrity Failures

This vulnerability arises when software updates, critical data, or CI/CD pipelines are not properly protected. Attackers can manipulate software or data to introduce malicious code or alter functionality.

For example, if a web app downloads libraries or updates from untrusted sources, attackers could inject malware. Or, if code repositories are not secured, attackers might introduce backdoors.

Always verify the integrity and authenticity of software and data sources before deploying to production.

9. Security Logging and Monitoring Failures

Without proper logging and monitoring, attacks can go unnoticed and response times lag. Detecting suspicious activity early is essential for limiting damage.

For instance, a lack of alerts for repeated failed login attempts might allow a brute-force attack to proceed undetected. Or, an attacker exploiting a vulnerability could cover their tracks if logs are not kept securely or analyzed proactively.

Effective logging is not about collecting everything, but about collecting meaningful data and reviewing it regularly.

10. Server-Side Request Forgery (SSRF)

SSRF vulnerabilities allow attackers to force a server to make HTTP requests to unexpected locations. This can be used to access internal resources, such as databases or cloud metadata endpoints, that are not otherwise accessible from the internet.

Picture a web app that fetches profile images via a supplied URL. If the app doesn’t validate the destination, an attacker could instruct it to fetch sensitive internal URLs, sometimes leading to data exposure or further network compromise.

Always validate and sanitize URLs and other user-supplied input that will be used in server-side requests.

Bringing It All Together

Web application security is not just about patching bugs or installing firewalls. It’s a continuous, holistic process that demands attention at every stage of development and deployment. Each item on the OWASP Top Ten represents a common, real-world risk – but awareness is the first step toward mitigation.

For those just starting out in technology, understanding these vulnerabilities is a powerful way to build responsible, robust, and user-friendly web applications. For women, neurodivergent learners, and anyone new to tech, remember: security is everyone’s job, and curiosity is your greatest asset. Ask questions, explore how things work under the hood, and never hesitate to experiment in safe environments. The internet is shaped by those who dare to learn, and your journey is just beginning.

Stay curious, stay secure, and welcome to the fascinating world of web application security.