PS31. User-data Value Modulation and Reserved/Unused

Initial publication	W. Mazurczyk, S. Wendzel, K. Cabaj in [3]. However, this pattern is based on the original PS11 Value Modulation and PS12 Rserved/Unused Patterns, which were introduced by S. Wendzel, S. Zander, B. Fechner, C. Herdin in [1].
Illustration	Characteristic features of user-data can be utilized to store secret information. This includes applying methods like LSB modification to speech samples or digital images carried within the payload field. Compared with previous patterns this is a targeted modification. This pattern is analogous to the combination of the patterns.
Context	Network Covert Channel Patterns → Covert Storage Channel Patterns → Modification of Payload → User-data Aware
Evidence	See [3] for references. At least the following ideas were published that belong to this pattern: 1. Encode a stream of information by spreading the encoded data across as much of the frequency spectrum as feasible (e.g. DSSS). 2. Embeds secret data into a carrier audio signal by introducing an echo (a.k.a. echo hiding). 3. Replacing the least significant bit of e.g. each voice sample with secret data (LSB).
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.

[2] W. Mazurczyk, S. Wendzel, S. Zander, A. Houmansadr, K. Szczypiorski: Information Hiding in Communication Networks, Wiley, 2016. Chapters 3 and 8 contain discussions on hiding patterns, basically on the basis of [1] but with an extension of timing-based patterns.

[3] W. Mazurczyk, S. Wendzel, K. Cabaj: Towards Deriving Insights into Data Hiding Methods Using Pattern-based Approach, in Proc. Second International Workshop on Criminal Use of Information Hiding (CUING 2018) at ARES, pp. 10:1-10:10, ACM, 2018.