<s>
Back	B-Protocol
Orifice	I-Protocol
(	O
often	O
shortened	O
to	O
BO	O
)	O
is	O
a	O
computer	B-Application
program	I-Application
designed	O
for	O
remote	B-Protocol
system	I-Protocol
administration	I-Protocol
.	O
</s>
<s>
It	O
enables	O
a	O
user	O
to	O
control	O
a	O
computer	O
running	O
the	O
Microsoft	B-Application
Windows	I-Application
operating	I-Application
system	I-Application
from	O
a	O
remote	O
location	O
.	O
</s>
<s>
The	O
name	O
is	O
a	O
play	O
on	O
words	O
on	O
Microsoft	B-General_Concept
BackOffice	I-General_Concept
Server	I-General_Concept
software	O
.	O
</s>
<s>
Back	B-Protocol
Orifice	I-Protocol
has	O
a	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
architecture	I-Operating_System
.	O
</s>
<s>
A	O
small	O
and	O
unobtrusive	O
server	O
program	O
is	O
on	O
one	O
machine	O
,	O
which	O
is	O
remotely	O
manipulated	O
by	O
a	O
client	O
program	O
with	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
on	O
another	O
computer	O
system	O
.	O
</s>
<s>
The	O
two	O
components	O
communicate	O
with	O
one	O
another	O
using	O
the	O
TCP	B-Protocol
and/or	O
UDP	B-Protocol
network	B-Architecture
protocols	I-Architecture
.	O
</s>
<s>
In	O
reference	O
to	O
the	O
Leet	B-Language
phenomenon	O
,	O
this	O
program	O
commonly	O
runs	O
on	O
port	B-Protocol
31337	O
.	O
</s>
<s>
Although	O
Back	B-Protocol
Orifice	I-Protocol
has	O
legitimate	O
purposes	O
,	O
such	O
as	O
remote	B-Protocol
administration	I-Protocol
,	O
other	O
factors	O
make	O
it	O
suitable	O
for	O
illicit	O
uses	O
.	O
</s>
<s>
For	O
those	O
and	O
other	O
reasons	O
,	O
the	O
antivirus	B-Application
industry	O
immediately	O
categorized	O
the	O
tool	O
as	O
malware	O
and	O
appended	O
Back	B-Protocol
Orifice	I-Protocol
to	O
their	O
quarantine	O
lists	O
.	O
</s>
<s>
Despite	O
this	O
fact	O
,	O
it	O
was	O
widely	O
used	O
by	O
script	O
kiddies	O
because	O
of	O
its	O
simple	O
GUI	B-Application
and	O
ease	O
of	O
installation	O
.	O
</s>
<s>
Two	O
sequel	O
applications	O
followed	O
it	O
,	O
Back	B-Protocol
Orifice	I-Protocol
2000	I-Protocol
,	O
released	O
in	O
1999	O
,	O
and	O
Deep	O
Back	B-Protocol
Orifice	I-Protocol
by	O
French	O
Canadian	O
hacking	O
group	O
QHA	O
.	O
</s>
