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B

B

B1

B1FF*

B2

B3

Backdoor account

Backdoor Trojan

Background checks

Background Investigations #

Background Processing

Backspace And Overstrike*

Back-To-Back Connection

Backup

Backup facility

Backup Procedures

Backup retention plan

Backward Channel

Backward Combatability*

Backward Recovery

BAD*

Band

Bandwidth Compression

Bang

Banner

Banner*

Base

Base C4 Systems Security Office

Base Computer Systems Security Officer

Basic Software (nonfunctional)

BASIC*

Basic/Generic Management Issues#

Batch Processing

Batch*

Baud

Bboard*

BBS

BCC

BCD

BCI

BCSSO

Bd

Beam*

Beep*

Behavioral scanning

Bell-La Padula Security Model

Bell-LaPadula Model

Bells And Whistles*

Benign

Benign Environment

BER

BERT

Beta*

Between-The-Lines Entry

Bible*

BiCapitalization*

Biff*

Big Red Switch*

Bignum*

Bigot*

Binary

Binary Exponential Backoff

Binary Notation

Binary Synchronous Communication

Binary-Coded Decimal

Binary-Coded Decimal Code

Binary-Coded Decimal Interchange Code

Binary-Coded Decimal Notation

Binary-Coded Decimal Representation

Binding

Binding/Handshaking#

Biometric authentication

B-ISDN

Bi-Sync

Bit

Bit Configuration

Bit Error Ratio

Bit Error Ratio Tester

Bit Stream Transmission

Bit Synchronization

Bitblt*

Bit-By-Bit Asynchronous Operation

Bit-Count Integrity

BITNET*

Bit-Paired Keyboard*

Bits Per Second

Bits*

Bit-Sequence Independence

Bit-Synchronous Operation

BIU

Bixie*

Black

BLACK Equipment Area (BEA)

Black hat hackers

Blast*

Blended threats

Blink*

Blit*

Blivet*

BLOB*

Block

Block Character

Block Check Character

Block encryption

Block Transfer Attempt

Block Transfer Computations*

Block Transfer Efficiency

Block Transfer Failure

Block Transfer Rate

Block Transfer Time

Block-Error Probability

Blocking Criterion

Blocking Factor

Blocking Formulas

Block-Loss Probability

Block-Misdelivery Probability

BLT*

Body

Border firewalls

Bourne Shell and Bourne Again Shell (BASH)

BPI

BPOC

BPS

BQS*

BR

Breach

Bridge

Broken*

Broket*

BRS*

Brute Force And Ignorance*

Brute-force guessing

BSA

BSD*

BSE

Budget

Budget And Accounting Act

Budget And Accounting Procedures Act Of 1950

Buffer

Buffer overflow

Buffer Overflow*

Bug

Bugging

Bulk Encryption

Bum*

Bump*

Burble*

Buried Treasure*

Burn-In Period*

Burst Transmission#

Bus

Bus Interface Unit

Business Aspects Of Information Security#

Business champions

Business continuity plan

Business process analysis

Buzz*

BW

BWQ*

Byte

Back Door

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 suggested the possibility of a back door in early UNIX versions that may have qualified as the most fiendishly clever security hack of all time (Thompson's presentation managed to be unclear on whether it was ever actually implemented or not). 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 talk that suggested this truly moby hack was published as "Reflections on Trusting Trust", "Communications of the ACM 27", 8 (August 1984), pp. 761--763.