A Novel Approach for Covert Communication Over TCP via Induced Clock Skew
Abstract
The goal of this thesis is to determine the feasibility and provide a proof of concept for a covert communications channel based on induced clock skew. Transmission Control Protocol (TCP) timestamps provide a means for measuring clock skew between two hosts. By intentionally altering timestamps, a host can induce artificial clock skew as measured by the receiver, thereby providing a means to covertly communicate. A novel scheme for transforming symbols into skew values is developed in this work, along with methods for extraction at the receiver. We tested the proposed scheme in a laboratory network consisting of Dell laptops running Ubuntu 16.04. The results demonstrated a successful implementation of the proposed covert channel with achieved bit rates as high as 33 bits per second under ideal conditions. Forward error correction was also successfully employed in the form of a Reed-Solomon code to mitigate the effects of variation in delay over the Internet.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2018
- Accession Number
- AD1181389
Entities
People
- Erik S Knebel
Organizations
- Naval Postgraduate School