As developers, we must always be vigilant about security vulnerabilities. One such vulnerability has been identified as CVE-2024-27980. This issue stems from the improper handling of batch files in both child_process.spawn and child_process.spawnSync, which are key components of Node.js applications. Specifically, a malicious command line argument can inject arbitrary commands and achieve code execution even if the shell option is not enabled.

In this long-read post, we will dive deep into the details of CVE-2024-27980. We will explore the code snippets that showcase the problem, provide links to original references, and discuss the exploit details.

Code Snippet Example

Before addressing the root cause of the problem, let's first take a look at a sample code snippet that uses the child_process.spawn function:

const { spawn } = require('child_process');
const child = spawn('node', ['--no-warnings', '-e', console.log(1+1)]);

This code example will execute a Node.js script that calculates the sum of 1 and 1, then logs the result to the console. On its own, this code appears to be harmless.

However, consider the following slight modification

const { spawn } = require('child_process');
const userInput = '1+1 & malicious-command-here';
const child = spawn('node', ['--no-warnings', '-e', console.log(${userInput})]);

In this adapted example above, a malicious user can potentially inject a harmful command (i.e., "malicious-command-here") directly into the spawn() function arguments, which can lead to code execution despite the shell option not being enabled.

Original References

1. Node.js Documentation: https://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options
2. Latest Node.js Security Releases: https://nodejs.org/en/blog/vulnerability/

Exploit Details

Now let's discuss the crux of this vulnerability, CVE-2024-27980. When the shell option is not enabled, both child_process.spawn and child_process.spawnSync are supposed to disallow arbitrary command execution. But this particular vulnerability allows attackers to bypass that feature.

The core issue lies in how batch files are processed during the spawning of new processes. When Node.js spawns a new process, it calls the command interpreter (cmd.exe) with the "/c" option and the target batch file's path as arguments. If an attacker injects an arbitrary command within the batch file path, it can be executed, causing a security breach.

For example, an attacker could craft the following payload

const { spawn } = require('child_process');
const userInput = 'node & malicious-command-here';
const child = spawn('cmd.exe', ['/c', ${userInput}.bat]);

In the above code snippet, the attacker has inserted the "& malicious-command-here" string into the path of the target batch file. Because the path is fed into the cmd.exe process without proper sanitization, code execution can occur.

Conclusion

It is crucial for developers to stay updated on the latest security vulnerabilities such as CVE-2024-27980 and take proper precautions to mitigate them. In this case, improper handling of batch files with child_process.spawn and child_process.spawnSync has led to the potential for arbitrary command execution. To secure your Node.js applications, commitment to continuous education in hardening your systems and best practices must take priority.

Timeline

Published on: 01/09/2025 01:15:08 UTC