A Covert Queueing Channel in FCFS Schedulers
This addresses security and privacy risks in shared systems like data centers, where covert channels can lead to information leakage, though it is incremental as it builds on existing covert channel research.
The paper tackles the problem of covert queueing channels (CQCs) in first-come-first-served (FCFS) schedulers, which allow information leakage between isolated users via timing patterns, and it computes the channel capacity and achievable transmission rates, demonstrating significant privacy threats.
We study covert queueing channels (CQCs), which are a kind of covert timing channel that may be exploited in shared queues across supposedly isolated users. In our system model, a user sends messages to another user via his pattern of access to the shared resource, which serves the users according to a first come first served (FCFS) policy. One example of such a channel is the cross-virtual network covert channel in data center networks, resulting from the queueing effects of the shared resource. First, we study a system comprising a transmitter and a receiver that share a deterministic and work-conserving FCFS scheduler, and we compute the capacity of this channel. We also consider the effect of the presence of other users on the information transmission rate of this channel. The achievable information transmission rates obtained in this study demonstrate the possibility of significant information leakage and great privacy threats brought by CQCs in FCFS schedulers.