How can IIS module functionality be used to bypass firewalls and achieve remote server management?

IIS module functionality, available from IIS7 onward, allows developers to extend IIS by creating custom modules that run within the w3wp.exe process. By reading HTTP request content and controlling HTTP response content, an attacker can implement a backdoor that communicates over allowed ports (80/443) without triggering firewall rules. Tools like IIS-Raid demonstrate this by registering event handlers for request/response processing, enabling remote command execution and shellcode injection. This technique was previously discussed in our article on bypassing firewalls using IIS port sharing.