Mitigation of Storage Covert Channels in IPSec for QoS Aware Applications

Abstract

Gateways implementing IPSec protocol suite are used to provide secure communication between different client machines over public infrastructure. However the exploitation of covert storage channel in the IPSec protocol may defeat the very purpose of protecting leakage of information from the client machine. This threat gets more aggravated as some of the channels might be exploited from the client machine even without compromising the security of the IPSec gateways. The possibility of information leakage by compromising only the client machine, either in form of a colluding insider or due to the presence of some malware at the client machine, poses a serious threat to any organization dealing with sensitive information and a resourceful adversary. The existing approaches to mitigate the threats against storage covert channels severely restrict the usability of many QoS aware applications by reducing the allowance of relevant header fields to minimum. This work overcomes the same by creating separate partitions based on application specific QoS requirements. Subsequent IPSec processing involves extension of the scope of security services as per the predefined QoS requirements. This is achieved by appropriate allowance of QoS related header fields using a comprehensive treatment of the storage and timing covert channels. When compared with existing approaches, the proposed approach provides better usability in QoS demanding contexts while maintaining equivalent strength of protection against storage covert channels and providing equivalent performance. The paper also outlines an implementation strategy of the same on Linux kernel IPSec stack.