Wi-Fi networks are safe only if you use the security features properly. If you don’t, someone nearby could access your wireless network, attack the PCs or other devices on your network and monitor your communications, stealing passwords for example. Weak wireless network security contributed to the largest identity theft fraud ever, according to the U.S. Department of Justice. Criminals obtained more than 40 million credit and debit card numbers by hacking into wireless computer networks of major retailers including TJX Companies, BJ’s Wholesale Club, OfficeMax, Boston Market, Barnes & Noble, Sports Authority, Forever 21 and DSW. Once inside the networks, they installed "sniffer" programs that captured card numbers, as well as password and account information, as they moved through the retailers’ credit and debit processing networks.