What can a hacker do with an MAC address?

A media access control address (MAC address), also called physical address, is aunique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used as a network address for most IEEE 802network technologies, including Ethernet and WiFi. Logically, MAC addresses are used in the media access control protocol sublayer of the OSI reference model.

1. Hackers will just spoof the mac address to retain there anonymity.
2. There never use original mac address and IP address.

How to do

1.  Finding the Device That You Want To Spoof.(wireshark)
2. Spoof the Mac Address To spoof the address go to Control Panel>Network Connections. Then right click on the connection you want to spoof and select properties. Now go to the advanced tab and click on Network Address. Then select the black box and type the MAC address you want to have. The form is 00:00:00:00:00:00.
3. Now Get Going (save and done)