CVE-2023-43655: Critical Vulnerability in Composer.phar Can Lead to Remote Code Execution

A newly discovered critical vulnerability, identified as CVE-2023-43655, affects Composer – a popular dependency manager for PHP. This vulnerability can potentially lead to remote code execution (RCE) if specific conditions are met. In this post, we will explore the details of this vulnerability, affected versions, as well as mitigation steps to protect your systems.

PHP has register_argc_argv enabled in the php.ini configuration file.

This configuration creates an environment where unauthorized actors can potentially exploit this vulnerability to execute arbitrary code on the affected server remotely.

Mitigation Steps

To mitigate this critical vulnerability, users should perform the following steps.

You can upgrade Composer using the following command

composer self-update

Or refer to the official Composer download page for more information on upgrading.

Disable the register_argc_argv option in php.ini

To ensure that your PHP environment does not allow unauthorized code execution, locate the php.ini configuration file (typically found in the /etc or /usr/local/etc directory), and disable the register_argc_argv setting by modifying it like this:

register_argc_argv = Off

Make sure you restart your web server to apply the changes.

Do not publish the composer.phar file to a publicly accessible web server

As a best practice, avoid publishing the composer.phar file on a public web server. Instead, store composer.phar securely behind your server's security layers and keep it away from public access.

Conclusion

The CVE-2023-43655 vulnerability is a critical security issue that can lead to remote code execution. It is essential to take the mitigation steps mentioned above, including upgrading to the latest Composer version, disabling register_argc_argv in php.ini, and following best practices to store composer.phar securely. By taking these steps, you can protect your PHP projects and web servers from potential attacks exploiting this vulnerability.

Timeline

Published on: 09/29/2023 20:15:09 UTC
Last modified on: 11/03/2023 21:15:16 UTC