PHP 8.1.0-dev Backdoor Remote Code Execution | RCE | PoC | FLAST101

PHP verion 8.1.0-dev was released with a backdoor on March 28th 2021, but the backdoor was quickly discovered and removed. If this version of PHP runs on a server, an attacker can execute arbitrary code by sending the User-Agentt header.

The original code was restored after the issue was discovered, but then tampered with a second time. The breach would have created a backdoor in any websites that ran the compromised version of PHP, enabling hackers to perform remote code execution on the site.