A survey of covert channels: Benign and malicious usage, conditions for creation and countermeasures

Abstract

Secure communication is of great importance to everyone, but how to secure a communication when a method that can hide its very existence exists? This can be achieved by a covert channel which can be used for a secret transfer of information. The following article gives a survey of the types of covert channels, the basic conditions for creating an undetectable covert channel as well as the countermeasures that can be taken for its limitation or elimination. An example of a covert channel attack (more specifically DNS tunneling) will be shown. The need for a data leak prevention system, a tool that helps safeguard the sensitive data will be punctuated. Some of the covert channels’ uses for corrupt causes will be mentioned. In some cases, security can be actually improved by the use of covert channels.