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Tobias Schmidbauer

Publications and source records attributed to Tobias Schmidbauer.

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Combining Different Existing Methods for Describing Steganography Hiding Methods

The proliferation of digital carriers that can be exploited to conceal arbitrary data has greatly increased the number of techniques for implementing network steganography. As a result, the literature overlaps greatly in terms of concepts and terminology. Moreover, from a cybersecurity viewpoint, the same hiding mechanism may be perceived differently, making harder the development of a unique defensive strategy or the definition of practices to mitigate risks arising from the use of steganography. To mitigate these drawbacks, several researchers introduced approaches that aid in the unified description of steganography methods and network covert channels. Understanding and combining all descriptive methods for steganography techniques is a challenging but important task. For instance, researchers might want to explain how malware applies a certain steganography technique or categorize a novel hiding approach. Consequently, this paper aims to provide an introduction to the concept of descriptive methods for steganography. The paper is organized in the form of a tutorial, with the main goal of explaining how existing descriptions and taxonomy objects can be combined to achieve a detailed categorization and description of hiding methods. To show how this can effectively help the research community, the paper also contains various real-world examples.

cs.CR

DYST (Did You See That?): An Amplified Covert Channel That Points To Previously Seen Data

Covert channels are stealthy communication channels that enable manifold adversary and legitimate scenarios, ranging from malware communications to the exchange of confidential information by journalists and censorship circumvention. We introduce a new class of covert channels that we call history covert channels. We further present a new paradigm: covert channel amplification. All covert channels described until now need to craft seemingly legitimate flows or need to modify third-party flows, mimicking unsuspicious behavior. In contrast, history covert channels can communicate by pointing to unaltered legitimate traffic created by regular network nodes. Only a negligible fraction of the covert communication process requires the transfer of covert information by the covert channel's sender. This information can be sent through different protocols/channels. Our approach allows an amplification of the covert channel's message size, i.e., minimizing the fraction of actually transferred secret data by a covert channel's sender in relation to the overall secret data being exchanged. Further, we extend the current taxonomy for covert channels to show how history channels can be categorized. We describe multiple scenarios in which history covert channels can be realized, analyze the characteristics of these channels, and show how their configuration can be optimized.

cs.CR