Hybrid covert channel in LTE-A: Modeling and analysis

As a major approach to information leakage, covert channels are rapidly gaining popularity with the exponentially growing of cloud computing and network resources. Long Term Evolution Advance (LTE-A) has dominated the 4th generation (4G) of mobile telecommunication networks, however, this brings an elevation of the risk of covert channels. This paper constructs a Covert Channel in LTE-A circumstance which can ensure the accuracy and effectiveness of the covert communication. Delayed Packet One Indicator (DPOI) is a Covert Timing Channel (CTC) model evolved from classic network CTC. Firstly, we use High-level Petri Nets (HLPN) to model the structure and behavior of the DPOI, especially the process of encoding/decoding and synchronization, according to which, we perform formal verification of the model's major shortcomings. Secondly, we propose HYBRID DPOI, an improved hybrid covert channel model which introduced Covert Storage Channel (CSC) in MAC layer for synchronizing. Moreover, we model the structure and behavior of the HYBRID DPOI using the HLPN to demonstrate the accuracy and effectiveness of our proposed model. At last, we analyze and evaluate the HYBRID DPOI. The results show that the proposed model in LTE-A circumstance is reliable and effective, which provides a new idea for covert channel construction.