Information Leakage behind the Curtain: Abusing Anti-EMI Features for Covert Communication

  • We present a new class of covert channels which can be created by utilizing common hardware but that cannot be detected by such. Our idea is to abuse anti-EMI features of a processor to create a covert channel on the physical layer. Thus, the sender uses the invariants in how digital signals are encoded over analog channels to covertly transport information. This leaked data is present on the wire bound connections of the compromised device, but is also by definition present in the vicinity of the device and can be picked up by radio equipment. As the covert channel is present only on the physical layer, the data on all layers above, as well as the timing behavior on those layers We present a new class of covert channels which can be created by utilizing common hardware but that cannot be detected by such. Our idea is to abuse anti-EMI features of a processor to create a covert channel on the physical layer. Thus, the sender uses the invariants in how digital signals are encoded over analog channels to covertly transport information. This leaked data is present on the wire bound connections of the compromised device, but is also by definition present in the vicinity of the device and can be picked up by radio equipment. As the covert channel is present only on the physical layer, the data on all layers above, as well as the timing behavior on those layers is indistinguishable from uncompromised devices. We present two example implementations of such channels using RS-232 as the carrier and use a common oscilloscope to decode the resulting covert channel. Using this setup, we observed symbol rates of around 5 baud. We derive the theoretical upper bound of the covert channels bandwidth and discuss the factors by which it is influenced.show moreshow less

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Metadaten
Author:Johannes Bauer, Sebastian Schinzel, Felix Freiling, Andreas Dewald
URN:urn:nbn:de:bvb:29-opus4-71576
Series (Volume number):Technical reports / Department Informatik (CS-2016-03)
Document Type:Report
Language:English
Year of Completion:2016
Embargo Date:2016/07/26
Publishing Institution:Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
Release Date:2016/07/27
SWD-Keyword:Covert channel; Elektromagnetische Verträglichkeit; Verdeckter Kanal
Pagenumber:1-11
Institutes:Technische Fakultät
CCS-Classification:C. Computer Systems Organization / C.m MISCELLANEOUS
Dewey Decimal Classification:Informatik, Informationswissenschaft, allgemeine Werke / Informatik, Wissen, Systeme / Informatik, Informationswissenschaft, allgemeine Werke
open_access (DINI-Set):open_access
Licence (German):Creative Commons - Namensnennung-NichtKommerziell

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