wormhole

wormhole
    n 1: hole made by a burrowing worm
    

Wormhole \Worm"hole`\, n.
   A burrow made by a worm.
   [1913 Webster]
    

wormhole
 /werm'hohl/, n.

   [from the wormhole singularities hypothesized in some versions of
   General Relativity theory]

   1. [n.,obs.] A location in a monitor which contains the address of a
   routine, with the specific intent of making it easy to substitute a
   different routine. This term is now obsolescent; modern operating
   systems use clusters of wormholes extensively (for modularization of
   I/O handling in particular, as in the Unix device-driver organization)
   but the preferred techspeak for these clusters is `device tables',
   `jump tables' or `capability tables'.

   2. [Amateur Packet Radio] A network path using a commercial satellite
   link to join two or more amateur VHF networks. So called because
   traffic routed through a wormhole leaves and re-enters the amateur
   network over great distances with usually little clue in the message
   routing header as to how it got from one relay to the other. Compare
   {gopher hole} (sense 2).
    

back door
wormhole

   <security> (Or "{trap door}", "{wormhole}").  A hole in the
   security of a system deliberately left in place by designers
   or maintainers.  The motivation for such holes is not always
   sinister; some {operating systems}, for example, come out of
   the box with privileged accounts intended for use by field
   service technicians or the vendor's maintenance programmers.
   See also {iron box}, {cracker}, {worm}, {logic bomb}.

   Historically, back doors have often lurked in systems longer
   than anyone expected or planned, and a few have become widely
   known.  The infamous {RTM} worm of late 1988, for example,
   used a back door in the {BSD} Unix "sendmail(8)" {utility}.

   {Ken Thompson}'s 1983 Turing Award lecture to the {ACM}
   revealed the existence of a back door in early {Unix} versions
   that may have qualified as the most fiendishly clever security
   hack of all time.  The C compiler contained code that would
   recognise when the "login" command was being recompiled and
   insert some code recognizing a password chosen by Thompson,
   giving him entry to the system whether or not an account had
   been created for him.

   Normally such a back door could be removed by removing it from
   the source code for the compiler and recompiling the compiler.
   But to recompile the compiler, you have to *use* the compiler
   - so Thompson also arranged that the compiler would *recognise
   when it was compiling a version of itself*, and insert into
   the recompiled compiler the code to insert into the recompiled
   "login" the code to allow Thompson entry - and, of course, the
   code to recognise itself and do the whole thing again the next
   time around!  And having done this once, he was then able to
   recompile the compiler from the original sources; the hack
   perpetuated itself invisibly, leaving the back door in place
   and active but with no trace in the sources.

   The talk that revealed this truly moby hack was published as
   ["Reflections on Trusting Trust", "Communications of the ACM
   27", 8 (August 1984), pp. 761--763].

   [{Jargon File}]

   (1995-04-25)