Attackers use search engines (Google Dorks) or automated scripts to find "Index of" pages containing the vendor/phpunit path.

The search result "index of vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php" refers to a critically severe vulnerability tracked as CVE-2017-9841 . This vulnerability occurs when the PHPUnit testing framework is incorrectly deployed in a production environment with its vendor directory publicly accessible via a web browser. Vulnerability Summary

eval($input);

Use your web server configuration to block all HTTP requests to the /vendor folder. Summary Checklist 💡 Scan: Search your project for eval-stdin.php .