There is no mac address on serial console ports. It's best to put proper username and password on the console login to prevent unauthorized users access:
sw01-12p(config)# aaa authentication console login
local Use local switch user/password database.
tacacs Use TACACS+ server.
radius Use RADIUS server.
peap-mschapv2 Use RADIUS server with PEAP-MSChapv2.
sw01-12p(config)# aaa authentication console login local