Parse Server is a popular open source backend platform that powers websites and applications seamlessly. It is designed with flexibility, supporting customizable deployments on various infrastructure environments that can run Node.js. However, Parse Server users must be vigilant about a crucial security vulnerability found in specific versions of the software.

CVE-2022-39396 denotes a serious vulnerability in Parse Server that leaves applications at risk of remote code execution through prototype pollution. This vulnerability affects versions of Parse Server prior to 4.10.18, as well as the 5.X branch before version 5.3.1. Upgrading to version 5.3.1 or 4.10.18 fixes this issue, and currently, no other workarounds are known.

In this in-depth post, we will explore prototype pollution, the use of a prototype pollution sink to exploit the vulnerability, and the impact of the vulnerability on MongoDB BSON parsing. We will provide insights into the vulnerability by sharing code snippets and references to the original publication.

Exploit Details

Remote Code Execution (RCE) is a critical security issue in which an attacker can exploit a vulnerability in a system to execute their arbitrary code. Prototype pollution involves modifying objects' prototypes by injecting properties into them, which can lead to unintended results when JavaScript programs rely on these object properties.

The issue in Parse Server results from its vulnerability to prototype pollution, which attackers can exploit to gain remote code execution via the MongoDB BSON parser. The MongoDB BSON parser is used in the process of serializing and deserializing data structures and plays a crucial role in the functioning of Parse Server.

Code Snippet

The vulnerable versions of Parse Server contain incorrect handling of input data, which can be leveraged by an attacker to pollute the prototype. Here is a simple example to illustrate this vulnerability:

// vulnerable_function.js
function saveData(input) {
  let data = {};
  for (let key in input) {
    if (key.includes('__proto__') || key.includes('constructor')) {
      // skip harmful keys
      continue;
    }
    data[key] = input[key];
  }
  // now the data object may be polluted by prototype properties
}

By exploiting this vulnerability, an attacker could manipulate the function to introduce potentially harmful code that may lead to remote code execution.

For those interested in understanding the issue in depth, the following are key references that provide further details about CVE-2022-39396, as well as the security patch that addresses it:

- CVE-2022-39396
- Parse Server Repository
- Patch for the Vulnerability in Parse Server Version 5.3.1

Conclusion

System administrators and developers who use Parse Server must take CVE-2022-39396 seriously and prioritize upgrading their system to versions 5.3.1 or 4.10.18 to mitigate the risk of remote code execution and prototype pollution. Given the severity of this vulnerability and the absence of alternative workarounds, staying informed and proactively addressing the issue is vital for maintaining a secure application or infrastructure environment.

Timeline

Published on: 11/10/2022 01:15:00 UTC
Last modified on: 11/11/2022 02:01:00 UTC