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                              Phrack  Seventeen
                                07 April 1988

                    File 9 of 12 : Data-Tapping Made Easy


--FEATURE ARTICLES AND REVIEWS-


 TAPPING COMPUTER DATA IS EASY, AND CLEARER THAN PHONE CALLS !

    BY RIC BLACKMON, SYSOP OF A FED BBS

        Aquired by Elric of Imrryr & Lunatic Labs UnLtd

Note from Elric:  This file was written by the sysop of a board for computer
security people (run on a CoCo), as far as I know the board no longer exists,
it was being crashed by hackers too much... (hehe).
---------------------

        FOR SEVERAL YEARS, I ACCEPTED CERTAIN BITS OF MISINFORMATION AS
TECHNICALLY ACCURATE, AND DIDN'T PROPERLY PURSUE THE MATTER.  SEVERAL FOOLS
GAVE ME FOOLISH INFORMATION, SUCH AS: A TAP INTERRUPTS COMPUTER DATA
TRANSMISSIONS; DATA COULD BE PICKED UP AS RF EMANATIONS BUT IT WAS A MASS OF
UNINTELLIGIBLE SIGNAL CAUSED BY DATA MOVING BETWEEN REGISTERS; ONE HAD TO BE
IN 'SYNC' WITH ANY SENDING COMPUTER; DATA COULDN'T BE READ UNLESS YOU HAD A
DIRECT MATCH IN SPEED, PARITY & BIT PATTERN; AND ONLY A COMPUTER OF THE SAME
MAKE AND MODEL COULD READ THE SENDING COMPUTER.  THIS IS ALL PLAIN SWILL.  IT
IS IN FACT, AN EASIER CHORE TO TAP A COMPUTER THAN A TELEPHONE.  THE TECHNIQUE
AND THE EQUIPMENT IS ALMOST THE SAME, BUT THE COMPUTER LINE WILL BE MORE
ACCURATE (THE TWO COMPUTERS INVOLVED, HAVE ERROR CORRECTING PROCEDURES) AND
CLEARER (DIGITAL TRANSMISSIONS HAVE MORE DISTINCT SIGNALS THAN ANALOG
TRANSMISSIONS).

FIRST, RECOGNIZE THAT NEARLY ALL DATA TRANSMISSIONS ARE SENT IN CLEARTEXT
ASCII SIGNALS.  THE LINES CARRYING OTHER BIT-GROUPS OR ENCIPHERED TEXTS ARE
RARE.  SECOND, THE SIGNAL APPEARS ON GREEN AND RED (WIRES) OF THE PHONE LINE
('TIP' AND 'RING').  THE DATA IS MOST LIKELY ASYNCHRONOUS SERIAL DATA MOVING
AT 300 BAUD.  NOW THAT 1200 BAUD IS BECOMING MORE CHIC, YOU CAN EXPECT TO FIND
A GROWING USE OF THE FASTER TRANSMISSION RATE.  FINALLY, YOU DON'T NEED TO
WORRY ABOUT THE PROTOCOL OR EVEN THE BAUD RATE (SPEED) UNTIL AFTER A TAPED
COPY OF A TRANSMISSION IS OBTAINED.

        IN A SIMPLE EXPERIMENT, A TAPED COPY OF A DATA TRANSMISSION WAS MADE
WITH THE CHEAPEST OF TAPE RECORDERS, TAPPING THE GREEN AND RED LINES BEYOND
THE MODEM.  THE RECORDING WAS THEN PLAYED INTO A MODEM AS THOUGH IT WERE AN
ORIGINAL TRANSMISSION. AT THAT POINT, HAD IT BEEN NECESSARY, THE PROTOCOL
SETTINGS ON RECEIVING TERMINAL COULD HAVE BEEN CHANGED TO MATCH THE TAPE.  NO
ADJUSTMENTS WERE NECESSARY AND A NICE, CLEAR ERROR-FREE DOCUMENT WAS RECEIVED
ON THE ILLICIT VIDEO SCREEN AND A NEAT HARD-COPY OF THE DOCUMENT CAME OFF THE
PRINTER.  THE MESSAGE WAS INDEED CAPTURED, BUT HAD IT BEEN AN INTERCEPTION
INSTEAD OF A SIMPLE MONITORING, IT COULD HAVE BEEN ALTERED WITH A SIMPLE WORD
PROCESSOR PROGRAM, TO SUIT ANY PURPOSE, AND PLACED BACK ON THE WIRE.

        WERE I TO HAVE AN INTEREST IN INFORMATION ORIGINATING FROM A
PARTICULAR COMPANY, AGENCY, OR OFFICE, I THINK THAT I WOULD FIND IT FAR MORE
PRODUCTIVE TO TAP A DATA TRANSMISSION THAN TO TAP A VOICE TRANSMISSION, AND
EVEN MORE REWARDING THAN GETTING HARDCOPY DOCUMENTS.

        *SIGNIFICANT & IMPORTANT INFORMATION IS MORE CONCENTRATED IN  A DATA
         TRANSMISSION.
        *SIGNIFICANT & IMPORTANT INFORMATION IS MORE EASILY LOCATED IN DATA
         TRANSMISSIONS THAN IN MASSES OF FILES OR PHONE CALLS.
        *TRANSMITTED DATA IS PRESUMED TRUE, AND WHEN ALTERATION IS DISCOVERED,
         IT'S READILY BLAMED ON THE EQUIPMENT.
        *THE LAWS CONCERNING TAPS ON UNCLASSIFIED AND NON-FINANCIAL COMPUTER
         DATA ARE EITHER QUITE LACKING OR ABJECTLY STUPID.

THE POINT OF ALL THIS IS THAT THE PRUDENT MANAGER REALLY OUGHT TO ENCRYPT ALL
DATA TRANSMISSIONS.  ENCRYPTION PACKAGES ARE CHEAP (A 'DES' PROGRAM IS NOW
PRICED AT $30) AND ARE EASY TO USE.

-------------------------------