Attempting to trick other users into providing password and login information is commonly called "phishing".
Steam Support does not use the Friends network to contact users, nor will we request CD Key information or credit card purchase information unless you have contacted us for assistance by using the Steam Support System.
Often times sites pretending to be an official Steam site will ask for login information typically offering free keys, deals on games, etc... Beware of phony sites, and make sure you are visiting an official, secure Steam site.