From: nestey@copper.denver.colorado.edu (Nathan F. Estey) Newsgroups: alt.security,comp.dcom.lans.fddi Subject: Re: Fiber optic networks and security Message-ID: <2949@copper.Denver.Colorado.EDU> Date: 8 May 92 19:42:29 GMT References: <1992May7.130246.19425@unix.brighton.ac.uk> <1992May7.214942.14298@adobe.com> Organization: University of Colorado at Denver Excerts from an unpublished paper: The SUBTERRANEAN CRYPTOLOGIC BLUES (SCB) ...must bust in early May, orders from the DA, phones tapped anyway... (with apologies to Bob Dylan) ***ROUGH DRAFT*** -------------------------------------------------------------------- Vulnerability of transmission media to interception: -------------------------------------------------------------------- FO: A)The first tap is inserted in series to the cable (the cable is cut, so must be inactive when installed), the signal is amplified and split, half going to the listening device, the other half being retransmitted through the fiber.[Hig88] B)The second tap can be installed on an active line, it relies on stripping some of the insulation arround the cable, and kinking it so that some of the light escapes (called coupling out light). This is split, amplified, and retransmitted as above.[Hig88] C)Inmacs computer supply catalog listed 3 devices, 2 of them serial requiring an inactive line for instalation, and type BNC or N series connectors. The third device is more interesting, it can be clipped on to an active line, and will pick up signals through the sheilding. The devices cost 275$ each.[Hig88] D)Our forth technique involves stripping and kinking the line twice, a secondary laser beam is pumped into the cable, and removed a bit later after entraining (picking up the modulation of the primary beam) the signal. This causes no signal loss, so there is no need to reamplify and reinsert it.[IEE88] E)I'm going to quote this one: 'Some fiber optic cables include a steel stabalizing central member. This type of cable should be avoided in aplications where computer security is of importance because the steel stabalizer acts as an antenna for the signals, even though fiber cable does not use the steel stabalizer for transmission.[Ayr87] (how light is converted into RF energy, I know not...) F)And finally, as with the coax, above, on long hauls FO will periodically need to have the signal boosted by a repeater, the process of light==> electricity==>amp==>light will give off RF radiation that can be picked up passivly about a mile away (with a highly directional antena and a suitable receiver). Another option would be to put an inductive tap within the repeater site, along with a transmitter or tape recorder. It should be noted that government agencies have taken to monitoring the signal strength and quality rather carfully. Rummors also abound of devices similar in function to what TDR is to twisted pair. (That is using a doppler like effect to map out any and all connections to the line.) "Recent tests by federal agencies such as the NSA, CIA, and FBI have debunked the tap proof myth. FO offers immunity to jamming, EM interference, and EMP's. (maybe not this last one, there is government interest in sheilding FO cable against EMP's.) Counter intrusion equipment is desighned to monitor and detect any breach in optical transmission, using the principle that at least some loss in a lightwave signal will occure if a fiber line is tapped. Such equipment also enables a rapid pinpointing of where the intrusion is being made on the cable."[Com87] ----- [Ayr97] Ayres, J.D., "Applicability of Army Automation Security Guidance to Local Area Computer Network Security", Navy Postgraduate School, thesis March '87 AD-A181-462 referencing: Rosenthal, R. "Transmission Media", reprinted from NBS Special Publication 500-96 Nov.'82 in Tutorial Local Network Technology, pp19-34 IEEE Computer Society Press'83 [Com87] Communications Week, 4/13/87, reprinted in LOD/TJ#2 (government countermeasures to FO tapping) [COR86] Cornwell, H., "The Hackers Handbook", E. Arthur Brown Co., '86 (electrical line spike signatures) [HIG88] Highland, H.J., "How Secure are Fiber Optics Communications?" Computers and Security, v8n7, pp25-26 [IEE88] IEEE, "Tapping Optical Fibers", IEEE Spectrum, June '88 pp17-18 [Sel90] Seline, C.J., "Eavesdropping On the Electromagnetic Emulations of Digital Equipment: The Laws of Canada, England, and the United States" rough draft of an unpublished paper. '90 (good refs + tech discussion) [SMU90] Smulders, P., "The Threat of Information Theft by Reception of Electromagnetic Radiation from RS-232 Cables" Computers and Security, v10n9, '90, pp53-58 [Ukn??] unknown author, "Monitoring Phone Calls With a TVRO", posted to ARPANET, and reprinted in 2600 spring88 issue, pp4-8 (discusses technical details of monitoring microwave linked telephone traffic using widely available ham satelite equip and/or plain satellite TV receiving equip.) [Ukn84] unknown author, "Some Thoughts on Garbage Picking", 2600 magazine v1n1, jan'84, p10 (discussion of crosstalk amplifiers) [VAN85] Van Eck, W., "Electromagnetic Radiation from Vidio Display Units: An Eavesdropping Risk?", Computers and Security v5n4, '85, pp269-286 (see the feedback column for about a year following, for additional information and part of the schematic that was intentionally left out - this artical is specific to european VDU's the counterpart of american CRT's, they have different syncs, a good source of plans for the american version is consumertronics)