IPv6 is next generation Internet protocol whose market is going to increase as IPv4 addresses are exhausted and more mobile devices are attached to Internet. The experience with IPv6 protocol is less as its deployment is slow. So there are many unknown threats possible in IPv6 networks. One such threat addressed in this paper is covert communication in the network. Covert channel is way of communicating classified information. In network it is done by network protocol's control fields. Destination option Extension header of IPv6 is used to pass secret information which is shown experimentally in real test network set up. For creation of attack packets Scapy-Python based API is used. Covert channel due to unknown option and nonzero padding in PadN option is shown. Their detection is also proposed and detector logic is implemented using shell scripting and C programming.