Today’s discussion is about a server-side vulnerability called JSON Injection. This flaw occurs when an application improperly handles user-supplied JSON data, allowing an attacker to manipulate the structure of the JSON object to alter the application’s behavior. JSON Injection can lead to data modification, privilege escalation, and even remote code execution in certain cases.
🔍 What is JSON Injection?
JSON (JavaScript Object Notation) is a lightweight data format widely used in web applications for transmitting structured information between a client and a server. JSON Injection happens when an attacker manipulates the JSON payload sent to the server, leading to unintended consequences like unauthorized access or data tampering.
How Does JSON Injection Occur?
This vulnerability typically arises in applications that:
✅ Trust JSON input without validation
✅ Dynamically parse and use JSON properties without sanitization
✅ Use insecure deserialization or poorly implemented API logic
🎥 Real-World Demo: JSON Injection in PinewoodStore
In our upcoming YouTube video, we will demonstrate how JSON Injection was exploited in our test application PinewoodStore to escalate privileges and create an Admin account!
📌 Scenario:
- The PinewoodStore web application has a vulnerable API that updates user roles.
- Normally, users can only update specific fields like their name and email.
- However, due to improper JSON validation, an attacker can inject additional parameters into the request and gain admin privileges.
💀 Exploiting JSON Injection: Step-by-Step
🔥 Step 1: Normal API Request
A legitimate user sends the following JSON to update their profile:
{
"username": "test_user",
"role": "user"
}
The backend processes this request and updates the user’s role to “user”.
💉 Step 2: Injecting Malicious JSON Data
An attacker modifies the JSON request to escalate their privileges:
{
"username": "attacker",
"role": "admin",
"isAdmin": true
}
If the backend does not validate or sanitize input, it may wrongly interpret "isAdmin": true and grant the attacker admin privileges!
🔓 Step 3: Gaining Admin Access
- The attacker successfully escalates privileges.
- They can now access sensitive data, modify user accounts, and perform admin-level actions!
🎬 Watch It Live!
We will walk you through each step of this attack in our upcoming YouTube video, showcasing how JSON Injection was used to create an Admin account in PinewoodStore! Stay tuned! 🚀
🛡️ How to Prevent JSON Injection
✅ 1. Implement Proper Input Validation
- Only accept expected JSON fields.
- Enforce strict data types and value checks.
✅ 2. Use Schema Validation
- Use libraries like Ajv (for JavaScript), Jackson (for Java), or JSON Schema to validate incoming JSON payloads.
✅ 3. Sanitize User Input
- Strip unexpected fields from JSON requests before processing them.
✅ 4. Avoid Using eval() or Unsafe Parsing Methods
- Avoid JavaScript’s
eval()function, which can execute injected code.
✅ 5. Implement Server-Side Authentication & Authorization
- Ensure role updates are only performed by authorized users and cannot be modified via client-side input.
🔚 Conclusion
JSON Injection is a severe vulnerability that can lead to account takeovers, privilege escalation, and data breaches if left unpatched. In our PinewoodStore demo, we showed how an insecure API allowed an attacker to gain Admin access simply by injecting additional JSON properties.
