PS12. Reserved/Unused Pattern (also P7)

Initial publication	S. Wendzel, S. Zander, B. Fechner, C. Herdin in [1]
Illustration	The covert channel encodes hidden data into a reserved or unused header/PDU element.
Context	Network Covert Storage Channels → Modification of Non-Payload → Structure Preserving → Modification of an Attribute
Evidence	M. Wolf. 1989. Covert channels in LAN protocols. In Proc. Local Area Network Security. LNCS, Vol. 396. Springer, 89–101. T. G. Handel and M. T. Sandford, II. 1996. Hiding Data in the OSI Network Model. In Proc. First Interna- tional Workshop on Information Hiding. Springer, London, UK, 23–38. K. Ahsan and D. Kundur. 2002. Practical Data Hiding in TCP/IP. In Proc. Workshop on Multimedia Security at ACM Multimedia ’02. See [1] for additional evidence entries.
Implementation	?

References:
[1] S. Wendzel, S. Zander, B. Fechner, C. Herdin: Pattern-based Survey and Categorization of Network Covert Channel Techniques, ACM Computing Surveys, Vol. 47, Issue 3, pp. 50:1-26, ACM, 2015.
An early version of the article is available here: download.