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2025-02-16
I recently discovered a Cross-Site Scripting (XSS) vulnerability on Khan Academy’s platform, where an attacker could leverage prototype pollution to inject arbitrary JavaScript, posing a significant security risk.
🔍 Vulnerability Overview:
The issue arises due to improper handling of JavaScript prototypes, which could allow an attacker to inject a malicious script into the web application. Exploiting this vulnerability can lead to potential remote code execution, compromising user data and interactions.
⚠️ Impact:
- User Impact: This vulnerability can affect users, potentially leading to the execution of malicious scripts in certain contexts.
- Exploitability: Although the attack requires specific conditions, the risk remains high if exploited via other attack vectors.
🔐 Mitigation Recommendations:
- Sanitize all user inputs, especially in dynamic JavaScript contexts.
- Implement a Content Security Policy (CSP) to block untrusted scripts.
- Protect sensitive methods like `__defineGetter__` to prevent prototype pollution.
📌 Status: This vulnerability has been reported under Khan Academy’s Vulnerability Disclosure Program (VDP) on HackerOne, where it was reviewed and marked as a duplicate, then closed.
It’s important to note that staying proactive in identifying and fixing such vulnerabilities strengthens the overall security posture of platforms.
Practice Verified Codes and Commands:
[javascript]
// Example of sanitizing user input in JavaScript
function sanitizeInput(input) {
return input.replace(/<script.?>.?<\/script>/gi, ”);
}
// Implementing a basic Content Security Policy (CSP) in HTML
// Protecting sensitive methods in JavaScript
Object.defineProperty(Object.prototype, ‘defineGetter‘, {
value: function() {
throw new Error(‘Prototype pollution attempt detected’);
},
writable: false,
configurable: false
});
[/javascript]
What Undercode Say:
Prototype pollution is a critical vulnerability that can lead to severe security breaches, including XSS attacks. To mitigate such risks, it’s essential to implement robust input sanitization, enforce strict Content Security Policies, and protect sensitive JavaScript methods. Regularly updating and patching your web applications can also help in maintaining a strong security posture. Additionally, leveraging tools like static code analyzers and vulnerability scanners can aid in identifying potential security flaws early in the development cycle.
For further reading on securing web applications, consider the following resources:
– OWASP XSS Prevention Cheat Sheet
– Mozilla Developer Network: Content Security Policy (CSP)
– HackerOne Vulnerability Disclosure Program
By staying informed and proactive, developers and security professionals can significantly reduce the risk of such vulnerabilities and ensure a safer web environment for all users.
References:
Hackers Feeds, Undercode AI
