SQLi allows an attacker to interfere with the queries an application makes to its database. On a login form, you could try the classic bypass payload: ' OR '1'='1 . If the backend code naively concatenates this string into an SQL query, it could allow you to log in as the first user in the database without a password.
Gruyere allows users to upload files, such as profile pictures. However, the application fails to validate the destination paths properly.
By stepping into the role of a hacker, you gain invaluable insight into the attacker's mindset. You learn to see the subtle cracks in an application's logic, the places where trusting the client can lead to disaster, and the hidden configuration pitfalls that await the unwary. The only way to truly know your enemy is to fight them on their own turf. So go ahead, launch your Gruyere instance, and start hacking. The best defense is a good offense.
It provides a safe sandbox to practice, which is more effective than theoretical knowledge.
Attackers can inject malicious scripts into snippets or file uploads. When another user views that page, the script executes in their browser, potentially stealing session cookies or redirecting them to a phishing site. gruyere learn web application exploits defenses top
You can inject JavaScript into user profiles or snippets to steal session cookies or deface the page.
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
: Path traversal exploits insufficient input sanitization to access files and directories that are stored outside the web root folder.
This is a high-risk vulnerability that allows an attacker to access files outside the intended directory. Web applications often serve static resources like images. If the path for an image is taken directly from a URL parameter without validation (e.g., download?file=profile.jpg ), an attacker can inject ../ (parent directory) sequences to navigate the server's file system. For example, a request to https://gruyere.com/123/../secret.txt could trick the server into reading the secret.txt file. SQLi allows an attacker to interfere with the
Treat all client-side data as completely untrusted. Store authorization states, privilege levels, and pricing data strictly within secure server-side databases or sessions.
Catch all errors at the application layer and map them to generic, user-friendly error messages.
The primary defense against XSS is encoding output data based on the context in which it appears (HTML, JavaScript, CSS, or URL).
By manipulating URL parameters or form inputs, you can gain unauthorized access to administrative functions. Gruyere allows users to upload files, such as
: This flaw allows an attacker to trick a logged-in user into performing unwanted actions on Gruyere, such as changing their password or deleting data, by clicking a malicious link. Path Traversal : Attackers manipulate file paths (e.g., using
| Exploit | Best Interactive Learning | |---------|----------------------------| | SQLi | PortSwigger SQLi labs, SQLMap tutorial | | XSS | XSS game (Google), Alert(1) to win | | CSRF | PortSwigger CSRF labs | | SSRF | HackTricks SSRF page, AWS metadata challenge | | Deserialization | Phoenix (HTB), Java Deserialization cheatsheet |
SQL Injection occurs when user input is directly concatenated into a database query.
Insecure Direct Object References (IDOR) and Access Control Flaws