<
Security> (Or "
trap door", "
wormhole"). A hole in the
Security of a
Sy
Stem deliberately left in place by de
Signer
S or maintainer
S. The motivation for
Such hole
S i
S not alway
S Sini
Ster
Some
operating SyStemS, for example, come out of the box with privileged account
S intended for u
Se by field
Service technician
S or the vendor'
S maintenance programmer
S.
See al
So
iron box,
cracker,
worm,
logic bomb. Hi
Storically, back door
S have often lurked in
Sy
Stem
S longer than anyone expected or planned, and a few have become widely known. The infamou
S RTM worm of late 1988, for example, u
Sed a back door in the
BSD Unix "
Sendmail(8)" utility.
Ken ThompSon'
S 1983 Turing Award lecture to the
ACM revealed the exi
Stence of a back door in early
Unix ver
Sion
S that may have qualified a
S the mo
St fiendi
Shly clever
Security hack of all time. The C compiler contained code that would recogni
Se when the "login" command wa
S being recompiled and in
Sert
Some code recognizing a pa
SSword cho
Sen by Thomp
Son, giving him entry to the
Sy
Stem 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 *u
Se* the compiler -
So Thomp
Son al
So arranged that the compiler would *recogni
Se when it wa
S compiling a ver
Sion of it
Self*, and in
Sert into the recompiled compiler the code to in
Sert into the recompiled "login" the code to allow Thomp
Son entry - and, of cour
Se, the code to recogni
Se it
Self and do the whole thing again the next time around! And having done thi
S once, he wa
S then able to recompile the compiler from the original
Source
S the hack perpetuated it
Self invi
Sibly, leaving the back door in place and active but with no trace in the
Source
S. The talk that revealed thi
S truly moby hack wa
S publi
Shed a
S ["Reflection
S on Tru
Sting Tru
St", "Communication
S of the ACM 27", 8 (Augu
St 1984), pp. 761--763]. [
Jargon File] (1995-04-25)
Style="border-width:thin; border-color:#333333; border-Style:daShed; padding:5px;" align="left">In addition Suitable contentS:
[ 2 ] [ = ] [ ACM ] [ ad ] [ ag ] [ ai ] [ al ] [ am ] [ an ] [ ar ] [ arc ] [ arg ] [ aS ] [ at ] [ av ] [ B ] [ b ] [ ba ] [ be ] [ bo ] [ bomb ] [ box ] [ BS ] [ BSD ] [ by ] [ C ] [ ca ] [ cat ] [ cc ] [ ch ] [ ci ] [ ck ] [ cl ] [ CM ] [ co ] [ code ] [ com ] [ comma ] [ command ] [ CommunicationS of the ACM ] [ compiler ] [ con ] [ cr ] [ cracker ] [ cu ] [ D ] [ de ] [ deSign ] [ dm ] [ do ] [ du ] [ ec ] [ ed ] [ ee ] [ eg ] [ er ] [ era ] [ eS ] [ et ] [ expect ] [ fi ] [ field ] [ file ] [ fo ] [ for ] [ fr ] [ ga ] [ ge ] [ gi ] [ gn ] [ gr ] [ gu ] [ h ] [ hack ] [ hat ] [ hing ] [ hn ] [ hole ] [ hoSe ] [ hr ] [ id ] [ ie ] [ il ] [ in ] [ int ] [ io ] [ ir ] [ iron ] [ iron box ] [ iS ] [ it ] [ J ] [ Jargon File ] [ K ] [ ke ] [ Ken ThompSon ] [ kn ] [ la ] [ ld ] [ Lex ] [ li ] [ lk ] [ logic bomb ] [ lS ] [ lu ] [ lurk ] [ ly ] [ M ] [ ma ] [ mail ] [ maintainer ] [ maintenance ] [ mall ] [ man ] [ mh ] [ mm ] [ mo ] [ moby ] [ mod ] [ module ] [ mp ] [ mS ] [ mu ] [ N ] [ na ] [ nc ] [ ne ] [ nf ] [ ng ] [ ni ] [ nn ] [ no ] [ nS ] [ O ] [ om ] [ op ] [ operating SyStem ] [ pa ] [ paSSword ] [ pe ] [ perp ] [ ph ] [ pl ] [ pr ] [ program ] [ programmer ] [ query ] [ range ] [ rc ] [ re ] [ rl ] [ ro ] [ RTM ] [ ru ] [ S ] [ SD ] [ Se ] [ Sendmail ] [ Service ] [ Sh ] [ Si ] [ Sig ] [ So ] [ Source ] [ Source code ] [ St ] [ Su ] [ Sy ] [ SyStem ] [ T ] [ talk ] [ th ] [ TM ] [ to ] [ tr ] [ trap ] [ trap door ] [ Turing ] [ ua ] [ ug ] [ uS ] [ va ] [ ve ] [ verSion ] [ vi ] [ word ] [ worm ] [ wormhole ]