Covert Channels of Data Communication

The article is dedicated to covert channels of data communication in the protected operating system based on the Linux kernel with mandatory access control. The channel which is not intended by developers violates security policy and can lead to disclosure of confidential information. In this paper the covert storage channels are considered. Authors show opportunities to violate the secrecy policy in the protected operating system based on the Linux kernel experimentally. The first scenario uses time stamps of the last access to the files (“atime” stamp), the second scenario uses unreliable mechanism of the automatic login to the user session with another level of secrecy. Then, there are some recommendations to prevent these violations. The goal of this work is to analyze the methods of using covert channels, both previously known and new. The result of the article is recommendations allowing to eliminate security threats which can be embodied through covert channels.