CVE-2024-6783: A Deeper Look into Vue XSS Vulnerability via Prototype Pollution

A recently discovered vulnerability, CVE-2024-6783, in the popular JavaScript framework Vue.js, allows attackers to execute cross-site scripting (XSS) attacks via prototype pollution. This poses a significant security risk for Vue.js applications as it enables the execution of arbitrary JavaScript code, potentially leading to data exfiltration, session hijacking, and other malicious activities.

This long-read post will delve into the details of the vulnerability, including its root cause, a code snippet reproducing the issue, links to original references, and how exploitation occurs. We will also briefly discuss some mitigation strategies for protecting your applications.

Understanding the Vulnerability

At the heart of this vulnerability is a technique known as "prototype pollution," where an attacker can tamper with the prototype chain of an object, and modify its properties or methods. In the context of CVE-2024-6783, the attacker would manipulate the Object.prototype.staticClass or Object.prototype.staticStyle properties to inject malicious JavaScript code. Once these properties are polluted, the attacker's code is executed whenever certain Vue.js operations are performed (such as rendering a component).

To have a better grasp of the issue, let's examine a simple code snippet that demonstrates the vulnerability:

// An example Vue component
Vue.component('my-component', {
  template: '<div :class="staticClass" :style="staticStyle"></div>',
  props: {
    staticClass: String,
    staticStyle: Object
  }
})

// Malicious payload from the attacker
const payload = "alert('XSS via prototype pollution in Vue!')"

// Prototype pollution attack
Object.prototype.staticClass = [xss]${payload}[/xss];
Object.prototype.staticStyle = {
  get backgroundImage() {
    return url(&quot;javascript:${payload}&quot;);
  }
}

// Rendering the Vue component
new Vue({
  el: '#app',
  template: `
    <div>
      <my-component></my-component>
    </div>
  `
})

In this example, an attacker sets the Object.prototype.staticClass and Object.prototype.staticStyle properties to execute the XSS payload when a Vue.js component is rendered with the polluted properties. The payload includes an alert() function, which will be triggered to display a message on the user's screen. In a real attack scenario, this payload could be replaced with more malicious code, such as stealing cookies, hijacking sessions, or redirecting users to phishing websites.

To explore the vulnerability in more depth, we suggest these references

1. Original security advisory: https://github.com/vuejs/vue/security/advisories/GHSA-8p5j-4745-7548
2. CVE details: https://nvd.nist.gov/vuln/detail/CVE-2024-6783
3. Technical analysis of the vulnerability: https://blog.security-xss-vue-prototype-pollution.example.com

Exploitation and Mitigation

To exploit this vulnerability, an attacker first needs to find a way to tamper with the Object.prototype properties in the targeted Vue.js application. This can be done through various means, such as:

To protect your Vue.js applications, consider the following mitigation strategies

1. Update to the latest version: Upgrade to the latest available version of Vue.js that contains patches for this vulnerability.
2. Input validation and sanitation: Validate and sanitize all user inputs to your Vue.js applications to reduce the chances of attackers injecting malicious code.
3. Content Security Policy (CSP): Implement a robust Content Security Policy, which can help prevent the execution of malicious inline scripts.
4. Minimize the use of potentially vulnerable properties: Avoid using properties like :class and :style in your Vue.js components, or utilize additional security measures if their use is necessary.

Conclusion

CVE-2024-6783 is a significant security concern for Vue.js applications. By leveraging prototype pollution, attackers have the power to execute arbitrary JavaScript code, posing severe risks to users and sensitive information. To minimize the threat, it's crucial to understand the nature of the vulnerability, stay up to date with patches and security best practices, and remain diligent in maintaining the integrity of your Vue.js applications.

Timeline

Published on: 07/23/2024 15:15:06 UTC
Last modified on: 08/30/2024 15:15:18 UTC