Information leakage through temperature based covert channels is a growing threat in modern multicore processors. Thus, accurately detecting the presence of such thermal covert communication channels in real time is crucial for ensuring the security of confidential data. Existing detection techniques fail when covert channels are implemented with low power benchmarks, as shown in this paper. A novel detection technique is proposed by considering the transitions in the CPU workload as the primary metric. The proposed approach can detect covert channels established with low power programs with 100% detection accuracy and less than 2% false positive rate.