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Covert channels in LAN protocols

  • Manfred Wolf
Section II: Protocols
Part of the Lecture Notes in Computer Science book series (LNCS, volume 396)

Abstract

Encryption is generally understood as being the basic mechanisms for LAN security. However, usage of encryption finds its limitations in case of an unauthorized information flow via covert channels. Some covert storage and timing channels inherent in a LAN's architecture are already described in the literature. This paper takes a more general approach. It shows, that there is a potential of unused bandwidth in commonly used LAN protocols (IEEE 802.2, 802.3, 802.4, 802.5), which might be exploitable as covert channel. The key point is, that exploitation of this potential of unused bandwidth is not a question of a LAN's architecture, but is strongly dependent on the design of its internal interfaces and on its implementations.

The paper describes how these channels may be blocked and emphasizes the necessity to investigate the design and implementation of the protocols as part of an evaluation of a LAN.

Keywords

Medium Access Control Trojan Horse Timing Channel Covert Channel Maximum Bandwidth 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. (1).
    German Cipherboard RFG, "National Catalog of Criteria for the Evaluation of Trusted IT Systems-Draft, Version 1, 23. Sept. 1988 to be published in 1989Google Scholar
  2. (2).
    Girling, C.G., "Covert Channels in LAN's", IEEE Transactions on Software Engineering, Vol. SE-13, No.2, February 1987Google Scholar
  3. (3).
    Haigh, J.T., R.A. Kemmerer, J.Mc Hugh, and W.D. Young, "An Experience Using Two Covert Channel Analyses Techniques on a Real System Design", 1986 IEEE Symposium on Security and PrivacyGoogle Scholar
  4. (4).
    IEEE Standard 802.2, "Logical Link Control", 1985Google Scholar
  5. (5).
    IEEE Standard 802.3, "Carrier Sense Multiple Access with Collision Detection", 1985Google Scholar
  6. (6).
    IEEE Standard 802.4, "Token-Passing Bus Access Method", 1985Google Scholar
  7. (7).
    IEEE Standard 802.5, "Token Ring Access Method", 1985Google Scholar
  8. (8).
    National Computer Security Center, "Trusted Computer System Evaluation Criteria", U.S. DoD 5200-28-St D., 1985Google Scholar
  9. (9).
    National Computer Security Center "Trusted Network Interpretation of the Trusted Computer System Evaluation Criteria", 1987Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • Manfred Wolf
    • 1
  1. 1.TELE-CONSULTING GMBH Miosga + Steinle UnternehmensberatungGäufelden 1Federal Republic of Germany

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