CVE-2022-27008 - Nginx NJS .7.2 Vulnerable to Buffer Overflow, Exploit Details, and Protection

In this post, we will discuss a recent vulnerability discovered in Nginx NJS .7.2, which is vulnerable to a Buffer Overflow attack. The vulnerability has been identified as CVE-2022-27008 and affects the Array.prototype.concat() function when a slow array appended element is a fast array.

The exploit can lead to unexpected behavior, system crashes, and potentially be leveraged by attackers to gain control of an affected system. To help you secure your Nginx NJS setup, we will provide an overview of the vulnerability, a proof-of-concept code snippet to demonstrate the exploit, helpful links to original references, and recommendations for addressing this issue in your environment.

Vulnerability Details

CVE-2022-27008 refers to a vulnerability in Nginx NJS .7.2, a version of the JavaScript engine used for scripting Nginx web servers. The vulnerability is caused by a type confusion issue in the Array.prototype.concat() function when a slow array appended element is a fast array.

This means that the process of joining two arrays using the concat() method can cause a buffer overflow when certain conditions are met. The execution can result in unpredictable behavior, causing the system to crash, hang, or potentially allow attackers to execute arbitrary code on the affected system.

The following code snippet demonstrates the Buffer Overflow vulnerability in Nginx NJS .7.2

// CVE-2022-27008 Proof-of-Concept
// Nginx NJS Buffer Overflow Exploit

function exploit() {
  // First slow array
  let slow_array = Array(5);
  slow_array[] = 1;

  // Second fast array
  let fast_array = [2, 3, 4];

  // Trigger the vulnerability using Array.prototype.concat()
  let vulnerable_array = slow_array.concat(fast_array);
}

exploit();

When the exploit function is executed, the resulting concat() operation will cause a Buffer Overflow in the affected Nginx NJS .7.2 JavaScript engine.

References

- NJS Github Repository
- CVE-2022-27008
- Nginx NJS Documentation

Upgrade Nginx NJS to the latest version, as the issue has been resolved in newer releases.

2. Ensure that appropriate security updates and patches for your Nginx installation are applied promptly.
3. Perform regular security audits and updates for Nginx configurations, modules, and third-party dependencies.

Implement proper input validation to avoid potential Buffer Overflow attacks.

By following the recommendations above, you can reduce the risk of this CVE-2022-27008 vulnerability impacting your Nginx NJS setup. Stay safe and keep your systems up to date.

Timeline

Published on: 04/14/2022 15:15:00 UTC
Last modified on: 05/19/2022 20:15:00 UTC