The command you've shared is: vendor phpunit phpunit src/util/php/eval-stdin.php exploit .
Let’s look at the actual source code of eval-stdin.php (simplified for clarity):
<?php // Significant portions omitted for brevity, but the core logic is: if (stream_get_contents(STDIN)) eval('?>' . stream_get_contents(STDIN));
If the HTTP response body contains the word Vulnerable , your site is actively exposed and exploitable. Step-by-Step Remediation and Prevention vendor phpunit phpunit src util php eval-stdin.php exploit
Indicators of compromise
In vulnerable versions, this script used eval() on data pulled from php://input .
: Older boilerplate installations or projects built around 2017 that have not updated their dependency trees. The command you've shared is: vendor phpunit phpunit
An attacker can exploit this by sending a specially crafted HTTP POST request to the vulnerable endpoint. Alert Logic Support Center
location ~ /vendor/ deny all; return 403;
In many shared hosting or poorly configured nginx/Apache setups, the web root points to the project root (where vendor/ lives) instead of a /public subdirectory. This exposes every vendor file to the world. Alert Logic Support Center location ~ /vendor/ deny
— Implement logging and alerting for access to eval-stdin.php . Any request to this file from external IPs should be treated as a potential security incident.
Due to a lack of access control within the file itself, if the web server is configured to execute .php files and the vendor directory is publicly accessible, remote attackers can execute arbitrary PHP code on the server by sending a specially crafted HTTP POST request.
In a web environment, php://stdin corresponds to the HTTP POST request body. Consequently, any HTTP POST request sent to this file — with a body beginning with <?php — would be blindly executed by the server.
SecRule REQUEST_URI "eval-stdin\.php" "id:10001,deny,status:403,msg:'PHPUnit RCE attempt'"
What or CMS (Laravel, WordPress, custom, etc.) you are running. Which web server software you use (Apache or Nginx).