| slovo | definícia |
back door
(encz) | back door,zadní dveře n: Radka D. |
Back door
(gcide) | Back door \Back" door"\
A door in the back part of a building; hence, an indirect
way. --Atterbury.
[1913 Webster] |
back door
(wn) | back door
n 1: a secret or underhand means of access (to a place or a
position); "he got his job through the back door" [syn:
back door, backdoor]
2: an undocumented way to get access to a computer system or the
data it contains [syn: back door, backdoor]
3: an entrance at the rear of a building [syn: back door,
backdoor, back entrance] |
back door
(foldoc) | back door
wormhole
(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)
|
back door
(jargon) | back door
n.
[common] 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. Syn. trap door; may also be called a
wormhole. 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. Ken Thompson's
1983 Turing Award lecture to the ACM admitted the existence of a back door
in early Unix versions that may have qualified as the most fiendishly
clever security hack of all time. In this scheme, the C compiler contained
code that would recognize 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 recognize 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
recognize 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 Turing lecture that reported this truly moby hack was later published
as “Reflections on Trusting Trust”, Communications of the ACM 27, 8 (August
1984), pp. 761--763 (text available at http://www.acm.org/classics/). Ken
Thompson has since confirmed that this hack was implemented and that the
Trojan Horse code did appear in the login binary of a Unix Support group
machine. Ken says the crocked compiler was never distributed. Your editor
has heard two separate reports that suggest that the crocked login did make
it out of Bell Labs, notably to BBN, and that it enabled at least one
late-night login across the network by someone using the login name “kt”.
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| | podobné slovo | definícia |
Back door
(gcide) | Back door \Back" door"\
A door in the back part of a building; hence, an indirect
way. --Atterbury.
[1913 Webster] |
hatchback door
(wn) | hatchback door
n 1: a sloping rear car door that is lifted to open [syn:
hatchback, hatchback door] |
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