They navigate to https://target.com/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php .
curl -X POST https://target.com/path/to/eval-stdin.php -d "<?php system('id'); ?>" The server evaluates system('id') and returns the output (e.g., uid=33(www-data) gid=33(www-data) ). index of vendor phpunit phpunit src util php evalstdinphp
Never deploy your vendor folder blindly. Use composer install --no-dev for production. Remove phpunit from your live environment. And always, always turn off directory indexing. Your future self will thank you when your server isn't listed in Shodan as a victim of CVE-2017-9041. They navigate to https://target
If you find an index of listing for this directory, you have effectively found a direct entry point to execute arbitrary code on the server. What exactly does eval-stdin.php do? Let’s look at the source code that historically shipped with PHPUnit versions before 4.8.28 and 5.6.3: Use composer install --no-dev for production
At first glance, this looks like a broken file path or a typing error. However, to a penetration tester or a system administrator, this string represents a red flag. It is a breadcrumb leading to a widely known Remote Code Execution (RCE) vulnerability (CVE-2017-9041) associated with PHPUnit, a popular unit testing framework for PHP.
If you see this in your logs, you are under attack. If you see this in your search console, your server is compromised. The combination of a mutable eval statement, a test file in production, and directory indexing creates a perfect storm for system takeover.