What are the various methods of passive OS fingerprinting?

In passive OS fingerprinting, an attacker installs a sniffer on any third party such as a router on which the victim communicates frequently. Now he studies the sniffer’s log and

Buffer Overflows

Buffer Overflow Overview Buffer overflows are the classic security vulnerability that have been around since the beginning of programming, and are still occurring everywhere today. Buffer overflows are very prevalent

Infection via HTML

Edit the code on what and how you need it, and yes this is detectable  in many cases, but you could insert a small FUD downloader to be  downloaded via