Web applications today handle sensitive data like personal information, payments, and business transactions. Unfortunately, they are also prime targets for cyberattacks.
According to OWASP (Open Web Application Security Project), most breaches occur due to common vulnerabilities that developers could have prevented.
In this article, we’ll cover the most frequent web app vulnerabilities, real-world examples, and practical steps you can take to secure your applications.
1. SQL Injection (SQLi)
- What it is: Attackers inject malicious SQL queries into input fields to manipulate databases.
Example: A login form without proper sanitization:
- SELECT * FROM users WHERE username = ‘admin’ AND password = ‘123’;
- If unprotected, attackers can bypass authentication.
Fix:
- Use prepared statements or parameterized queries.
- Example in Node.js with Sequelize:
- User.findOne({ where: { username: req.body.username } });
2. Cross-Site Scripting (XSS)
- What it is: Attackers inject malicious JavaScript into web pages.
- Impact: Steals cookies, hijacks sessions, or redirects users.
Fix:
- Implement Content Security Policy (CSP) headers.
- Use frameworks with built-in XSS protection (e.g., React auto-escapes JSX).
- Escape and sanitize all user input.
3. Cross-Site Request Forgery (CSRF)
- What it is: Forces a user to execute unwanted actions while authenticated.
- Example: Clicking a malicious link transfers money from the victim’s account.
Fix:
- Implement SameSite cookies.
- Use CSRF tokens in forms.
4. Broken Authentication
- What it is: Weak authentication methods allow attackers to gain unauthorized access.
Fix:
- Implement rate limiting to block brute-force attacks.
- Use multi-factor authentication (MFA).
- Enforce strong password policies.
5. Insecure Direct Object References (IDOR)
- What it is: Attackers manipulate object IDs to access unauthorized data.
- Example: Changing
/user/123/profileto/user/124/profile.
Fix:
- Never rely solely on user-provided IDs.
- Validate user authorization on the backend.
6. Security Misconfiguration
- What it is: Leaving default settings, open ports, or unnecessary services exposed.
Fix:
- Disable unnecessary features.
- Keep servers and libraries updated.
- Use security headers (
X-Frame-Options,X-Content-Type-Options).
7. Sensitive Data Exposure
- What it is: Poor handling of sensitive data (passwords, credit card info).
Fix:
- Encrypt data at rest and in transit (TLS/HTTPS).
- Hash passwords using bcrypt or Argon2.
- Never store secrets in code; use environment variables.
8. Using Vulnerable Dependencies
- What it is: Outdated libraries or frameworks contain known security holes.
Fix:
- Use tools like npm audit, OWASP Dependency Check, or Snyk.
- Regularly update dependencies.
9. Insufficient Logging & Monitoring
- What it is: Attacks go unnoticed due to lack of monitoring.
Fix:
- Conduct regular penetration testing.
- Set up alerts for suspicious activity.
- Implement centralized logging.
10. Best Practices for Secure Web Apps
- Follow the OWASP Top 10 guidelines.
- Adopt DevSecOps: integrate security into development pipelines.
- Educate your team about secure coding practices.
- Perform regular security audits.
Conclusion
Most web application attacks exploit common, preventable vulnerabilities. By understanding risks like SQL injection, XSS, CSRF, and misconfigurations, developers can significantly reduce security threats.
Securing your web app is not a one-time task—it’s an ongoing process of updating, monitoring, and testing. With the right strategies, you can protect your users, data, and brand from costly breaches.