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In this article, we are going to delve deep into the details of a recently detected critical security vulnerability, identified as CVE-2023-3696. This vulnerability has been found in the Mongoose library, specifically affecting all versions before 7.3.4. Mongoose is a widely used Object-Data Modeling (ODM) library for MongoDB, which makes it easier to work with MongoDB in Node.js applications. Due to the widespread use of Mongoose, this vulnerability poses a significant risk to numerous applications.

Description of CVE-2023-3696

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CVE-2023-3696 can be categorized as a Prototype Pollution vulnerability. In short, prototype pollution allows an attacker to manipulate the properties and behavior of JavaScript objects via their prototype. This is dangerous because these manipulations can result in unexpected application behavior, such as access control bypass, code execution, or Denial of Service attacks.

The vulnerability in the Mongoose library was first discovered by a security researcher and, upon investigation, it was confirmed by the Mongoose development team. They have promptly addressed the vulnerability by releasing a patched version (7.3.4) to prevent any potential exploitation.

Exploit Details

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Below, we'll walk you through the specifics regarding the code-level changes that led to this vulnerability and explain the potential exploit scenario.

The vulnerability exists in the Mongoose library because it does not properly validate and handle inputs before applying them to object prototypes. As a result, an attacker can potentially inject malicious input data that manipulates the prototype of an object in a way that leads to a security breach.

To better understand the issue let us consider the following code snippet from the Mongoose library

function mergeOptions(to, from) {
  var keys = Object.keys(from);
  var i = keys.length;
  while (i--) {
    if (typeof to[keys[i]] === 'undefined') {
      to[keys[i]] = from[keys[i]];
    } else if (isObject(from[keys[i]])) {
      mergeOptions(to[keys[i]], from[keys[i]]);
    }
  }
  return to;
}

The issue in the code exists specifically within the mergeOptions function. This function accepts two objects as input and merges their properties. It does so in a recursive manner, meaning that if a sub-object exists within one of the arguments, the merging happens recursively to drill down into the sub-objects.

In this process, the function does not validate whether the input is the actual object prototype. As a result, a malicious user might craft an input to compromise the application's security.

For example, an attacker could use the following payload to manipulate the prototype and cause a security breach:

{
  "__proto__": {
    "isAdmin": true
  }
}

If this payload manages to find its way into any Mongoose operation, it can potentially overwrite the isAdmin property of the application's user or admin object, thus potentially leading to unauthorized access.

Mitigation and Patch

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To mitigate this vulnerability and properly sanitize input data, the Mongoose development team has released version 7.3.4. The update includes checks to prevent prototype pollution attacks, ensuring that the prototype objects are not affected.

Users of Mongoose are strongly encouraged to update their library to version 7.3.4 or later as soon as possible. You can do so by simply updating the version in your project's package.json file and running the npm install command.

"dependencies": {
  "mongoose": "^7.3.4"
}

Original references

1. CVE-2023-3696 on NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-3696
2. GitHub Security Advisory: https://github.com/Automattic/mongoose/security/advisories/GHSA-v9f5-4xg2-c3h6
3. Mongoose library: https://mongoosejs.com/

Conclusion

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CVE-2023-3696 demonstrates the importance of properly validating and handling user input in software development. This vulnerability highlights the risks associated with prototype pollution attacks, which can lead to critical security breaches within an application. It is important to stay vigilant and keep up-to-date with the latest security updates to ensure that your applications remain secure and resilient against such threats.

Timeline

Published on: 07/17/2023 01:15:00 UTC
Last modified on: 08/02/2023 17:30:00 UTC