An IIS Module is an add-on component for Microsoft’s Internet Information Services (IIS) web server. These modules extend the web server’s functionality by handling specific tasks, such as authentication, URL rewriting, or logging web requests. While legitimate IIS modules help manage and secure web traffic, malicious modules can be secretly installed by attackers to hijack web traffic, steal sensitive data, or compromise server security. Understanding and monitoring IIS modules is important for maintaining a secure web server environment.