winnuke was the first "mainstream" denial-of-service attack wich have proof-of-concept avaiable for Windows, so it was the first TCP/IP Stack Denial Of Service attack avaiable do any Windows user, by sending an ICMP message type "Out Of Band" with urgent flag and without expected data, unpatched Windows would determine that the program that owns the port who received the message must be closed, and when it is applied to port 139 (wich is netbios session, owned by MS Networking code) Windows' TCP/IP Stack ceases its functionallity after issuing the infamous Blue Screen Of Death, other open ports are also vulnerable, but 139 was the most attacked