This note presents an overview of some abstract concepts regarding covert channels. It discusses primary means of synchronization and illicit interference between subjects in a multilevel computing environment, and it describes a detailed laboratory exercise utilizing these abstractions.

We discuss the di culties of satisfying high-assurance system requirements without sacri cing system capabilities. To alleviate this problem, we show how trade-o s can be made to reduce the threat of covert channels. We also clarify certain concepts in the theory of covert channels. Traditionally, a covert channel's vulnerability was measured by the capacity. We show why a capacity analysis alo...

Covert network timing channels control time between transmissions of packets in overt network communication and transmits hidden messages. This paper presents an overview of different concepts of covert timing channels such as types, features and properties. There is range of terms used for security of information such as encryption, covert channels, network steganography or information hiding ...

Covert channels have tmditionally been categorized as either stomge channels or timing channels[6, 71. This paper questions this categorization, and discwses channels that cannot be clearly identified as either stomge or timing channels, but have aspects of both. A new model of timing channels is presented, which allows for channels that have chamcteristics of both stomge channels and timing ch...

We present a secure kernelized architecture for multilevel object-oriented database management systems. Our architecture is based on the notion of a message lter proposed by Jajodia and Kogan. It builds upon the typical architecture of current object-oriented database management systems. Since the operations mediated by the message lter are arbitrarily complex operations (as opposed to primitiv...

Covert channels are a form of hidden communication that may violate the integrity of systems. Since their birth in Multi-Level Security systems in the early 70’s they have evolved considerably, such that new solutions have appeared for computer networks mainly due to vague protocols specifications. In this paper we concentrate on short-range covert channels and analyze the opportunities of conc...

Protecting sensitive data is no longer a problem restricted to governments whose national security is at stake. With ubiquitous Internet connectivity, it is challenging to secure a network – not only to prevent attack, but also to ensure that sensitive data are not released. In this paper, we consider the problem of ensuring that only pre-authorized data leave a network boundary using either ov...

The purpose of this work is the demonstration of an adversary intrusion into protected computing system, when the covert channels are poorly taken into account. We consider an opportunity of overcoming the protection mechanisms placed between a protected segment of a local area network and a global network (for example, Internet). We discuss the ability for a warden to reveal the covert channels.

We discuss the dificulties of satisfying high-assurance system requirements without sacrificing system capabilities. To alleviate this problem, we show how trade-offs can be made to reduce the threat of coved channels. We also clarify certain concepts in the theory of covert channels. Traditionally, a coved channel’s vulnerability was measured b y the capacity. We show why a capacity analysis a...

Communication is not necessarily made secure by the use of encryption alone. The mere existence of communication is often enough to raise suspicion and trigger investigative actions. Covert channels aim to hide the very existence of the communication. The huge amount of data and vast number of different protocols in the Internet makes it ideal as a high-bandwidth vehicle for covert communicatio...