ECE537/7 #1Spring 2009 © , Richard A. Stanley ECE537 Advanced and High Performance Networks 7: TEMPEST in a Network (or a teapot?) Professor Richard A. Stanley, P.E.

ECE537/7 #2 Overview of Tonight’s Class Student presentations/discussions on Review of last time Issues with compromising emanations and data separation

ECE537/7 #3 What’s the Problem? Anything carrying an electrical current produces a magnetic field, and vice versa –Faraday’s Law –Time-varying E fields cause time-varying B fields, and vice versa Computing and networking equipment uses digital circuitry operating at gHz rates with short rise/fall times –Pulses have wideband frequency spectra –Remember Fourier?

ECE537/7 #4 And? Electromagnetic waves above a certain (very low) frequency propagate through space in accordance with the laws of physics Thus, the high-frequency waves from our computing and networking equipment can potentially propagate and be received by those for whom they were not intended

ECE537/7 #5 Near/Far Fields

ECE537/7 #6 Fourier Series Examples

ECE537/7 #7 Not a New Phenomenon Serious work on compromising emanations began as early as the late 1950’s Initially, dealing with these emanations in U.S. Government systems was dealt with under the provisions of Federal Standard 222 (C) Eventually, FS 222 morphed into TEMPEST

ECE537/7 #8 What is TEMPEST? A series of regulations and standards for preventing compromising emanations from information-processing systems –Networks certainly meet this definition It is not an acronym for anything, although several interesting (and often profane) candidates have been suggested

ECE537/7 #9 Some Guidelines Most TEMPEST documents are classified Among those that are not, or are not entirely so, are –NSA/CSS REG 90-6, Technical Security Program –NSTISSAM TEMPEST/1-92, COMPROMISING EMANATIONS LABORATORY TEST REQUIREMENTS ELECTROMAGNETICS

ECE537/7 #10 Acronyms NSA: National Security Agency CSS: Central Security Service NSTISSAM: National Security Telecommunications and Information Systems Security Advisory Memorandum

ECE537/7 #11 Compromising Emanations Unintentional information-bearing signals transmitted, received, handled, or otherwise processed by any information-processing equipment, which, if intercepted and analyzed, potentially disclose national security information These signals can escape from a controlled area by power line conduction/induction, other fortuitous conduction paths such as air conditioning ducts, pipes, or by simply radiating a signal into the air

ECE537/7 #12 Legalities Interception of communications not intended for you is subject to the penalties provided by the “Wiretap Laws”, 18 USC § 2510 – 2521 Obviously, in an espionage setting (governmental or commercial), the perpetrator(s) are not usually too concerned about legal sanctions

ECE537/7 #13 And This Has to do With Networking How? Networking has increased the exposure of sensitive information to interception –Longer network backbones –Huge internetwork infrastructures –Much higher speed processing and transmission than even a few years ago Trend is for this to continue

ECE537/7 #14 The Color of Signals Red: signals carrying sensitive information without any form of protection (e.g. encryption), so that they can be read and understood Black: signals which have been protected (usually by encryption), so that merely having access to the signal does not give access to the information it bears

ECE537/7 #15 Name Creep Initially, Red and Black referred exclusively to signals meeting the definition Over time, the naming crept into descriptions of systems as well –Black network: one where all traffic is encrypted –Red network: one where traffic is not encrypted

ECE537/7 #16 Separation In processing and networking, it is essential to keep Red and Black signals separate –If commingled, separating them becomes a multi-level security problem, which we have not done a good job of solving –Worse, if Red signals can “hitch a ride” on Black signals, they can leave the controlled perimeter and thus be compromised

ECE537/7 #17 Demarcation If we are to keep Red and Black signals, networks, etc. separated, then it is crucial to know where one ends and the other begins –Typically known as the demarcation point –Must be a device, not a transmission path E.g., a crypto device is generally Red input and Black output, so it could connect a Red network to a Black network

ECE537/7 #18 How to do This? Shielding Grounding Filtering Unfortunately, these fields are as much art as science, and much has be passed on by skilled practitioners to newcomers –We must revisit our analog signal skills!

ECE537/7 #19 Grounding Examples - 1 This is a simple 3-wire grounded AC outlet connection What, if anything, is wrong with this diagram? Are these concerns universal at all frequencies?

ECE537/7 #20 Grounding Examples – 2

ECE537/7 #21 Coaxial Advantage

ECE537/7 #22 Effect of Cable

ECE537/7 #23 Shielded Twisted Pair At least, that is how it works in theory

ECE537/7 #24 E Fields and B Fields Are Different To shield an electric field, we seek to divert the electrical energy (i.e. current) to ground –Low-impedance path To shield a magnetic field, we seek to contain the magnetic field so it cannot propagate beyond the shield –What has this to do with grounding? –Magnetic vs. electrical impedance What if we contain only one field?

ECE537/7 #25 Star Network

ECE537/7 #26 Grounding All grounds are not created equal Goodness of the ground is frequency dependent

ECE537/7 #27 Other Problems Induction currents Faraday effects Sneak paths Surge protection Common-mode currents What about light and fibre?

ECE537/7 #28 Filtering How to protect what is inside a shielded enclosure? How to protect what is outside from what is inside the shield?

ECE537/7 #29 The Color of the Core Red Black Colorless

ECE537/7 #30 Summary While TEMPEST is a uniquely government program, the issue of compromising emanations is not; it affects all systems Sensitive information is not limited to government systems Networks exacerbate the compromising emanations problem, and they must be considered in network design

ECE537/5 #31Spring 2009 © , Richard A. Stanley Homework You are designing an Ethernet-based network (100BaseT) with wireless extensions. Users will process sensitive information on their workstations and need to exchange this information with other users at remote network sites. Cost is an overriding concern; commercial equipment is the only real option. The customer is very concerned about compromising emanations. How will you design this network? What will you do to evaluate your design? Are field measurements feasible? Prepare a paper of approximately 1100 words describing your findings. Be prepared to discuss your findings with the class for minutes next week. You may use slides if you desire.

ECE537/5 #32Spring 2009 © , Richard A. Stanley Disclaimer Parts of the lecture slides contain original work of Wolfram Math world and James M. Atkinson and remain copyrighted materials by the original owner(s). The slides are intended for the sole purpose of instruction in computer networks at Worcester Polytechnic Institute.