Adversaries may use fallback or alternate communication channels if the primary channel is compromised or inaccessible in order to maintain reliable command and control and to avoid data transfer thresholds.
Fallback Channels
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1008  external_id: T1008     source_name: University of Birmingham C2  description: Gardiner, J.,  Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.  url: https://arxiv.org/ftp/arxiv/papers/1408/1408.1136.pdf     