Senior LevelNode JS
How do you prevent Prototype Pollution and Remote Code Execution (RCE) in Node.js JSON parsing and object merging?
❓ Interview Prompt: Explain Prototype Pollution attacks, mutating Object.prototype, `__proto__` injection, RCE vulnerabilities, and freezing prototypes.
Prototype Pollution occurs when untrusted JSON input mutates 'Object.prototype', injecting malicious properties across ALL objects in the Node.js application:
Defense Strategies:
1
Use 'Object.create(null)' for key-value dictionary maps.
2
Freeze prototypes: 'Object.freeze(Object.prototype)'.
3
Validate incoming JSON with Zod/Ajv schemas, removing '__proto__' and 'constructor' keys.
Code Implementation Example
javascript
// Secure Object dictionary map with no prototype heritage
const safeMap = Object.create(null);
safeMap['key'] = 'value'; // Cannot pollute Object.prototype!
// Freeze Object prototype against dynamic mutations
Object.freeze(Object.prototype);💡Preventing Prototype Pollution by freezing Object.prototype.
🎯 Interview Key Takeaway
Use Object.create(null) or schema validation to prevent Prototype Pollution security vulnerabilities.
#Prototype Pollution#Security#Object.prototype#Senior
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