Gruyere Learn Web Application Exploits Defenses Top ((free)) -

Store sensitive state information (like user roles and privileges) on the server. The client cookie should only hold a cryptographically random, unique session ID.

| Resource | Focus | Format | |----------|-------|--------| | | All major exploits + labs | Interactive browser labs | | OWASP Juice Shop | Hacking a fake e‑commerce site | Self‑hosted / online demo | | TryHackMe (Web Fundamentals path) | Beginner-friendly | Guided VM | | HackTheBox (Starting Point / Machines) | Realistic challenges | VPN + targets | | Damn Vulnerable Web App (DVWA) | Classic local training | PHP/MySQL local VM |

Convert untrusted input into a safe form before displaying it. Use HTML entity encoding (e.g., converting < to < ) so the browser treats the input as text rather than executable code.

You can immediately see the impact of an exploit and the effectiveness of your fix. Conclusion gruyere learn web application exploits defenses top

Set-Cookie: session_id=xyz123; Secure; HttpOnly; SameSite=Lax Use code with caution.

Cross-Site Scripting occurs when an application includes untrusted data in a web page without proper validation or escaping. This allows attackers to execute malicious scripts in the victim’s browser. Exploitation Techniques

Try to find bugs just by interacting with the site. Store sensitive state information (like user roles and

A simple login form vulnerable to SQLi and XSS.

The browser automatically appends the user's valid session cookie, executing the deletion without their knowledge. The Defense

If you must allow HTML input, pass the data through a rigorous, battle-tested sanitization library (like DOMPurify) to strip out dangerous tags and attributes. Client-Side State Manipulation (Cookie Vulnerabilities) Use HTML entity encoding (e

Typical exploitation techniques demonstrated

The attacker injects a script into data stored permanently on the server (e.g., database, comment section). Every user who views the infected page executes the payload.

Sample lab setup script using Docker (DVWA + ModSecurity + OWASP CRS).

Path traversal allows attackers to access files and directories that are stored outside the web root folder [1].

Use libraries that automatically escape HTML special characters (e.g., converting < to < ). 2. Defending Against CSRF: Anti-CSRF Tokens