% = % = % = % = % = % = % = %
                        =                           =
                        %   P h r a c k   X V I I   %
                        =                           =
                        % = % = % = % = % = % = % = %
 
                              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 MISINFORMA-
TION  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 COM-
PUTER. 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
ENCYPHERED TEXTS ARE RARE. SECOND, THE SIGNAL  APPEARS  ON  GREEN
AND RED (WIRES) OF THE PHONE LINE ('TIP' AND 'RING'). THE DATA IS
MOST LIKELY ASYSCHRONOUS 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  TRANSMIS-
SION  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  CAP-
TURED,  BUT HAD IT BEEN AN INTERCEPTION INSTEAD OF A SIMPLE MONI-
TORING, 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 INFOR-
MATION 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,  ITS  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.

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


                                        The Sorceress



From Lunatic Labs UnLtd. 415-278-7421