<s>
A	O
code	B-Operating_System
cave	I-Operating_System
is	O
a	O
series	O
of	O
unused	O
bytes	O
in	O
a	O
process	B-Operating_System
's	O
memory	O
.	O
</s>
<s>
The	O
code	B-Operating_System
cave	I-Operating_System
inside	O
a	O
process	B-Operating_System
's	O
memory	O
is	O
often	O
a	O
reference	O
to	O
a	O
section	O
that	O
has	O
capacity	O
for	O
injecting	O
custom	O
instructions	O
.	O
</s>
<s>
The	O
concept	O
of	O
a	O
code	B-Operating_System
cave	I-Operating_System
is	O
often	O
employed	O
by	O
hackers	B-Application
and	O
reverse	O
engineers	O
to	O
execute	O
arbitrary	O
code	O
in	O
a	O
compiled	O
program	O
.	O
</s>
<s>
Often	O
using	O
a	O
call	O
instruction	O
commonly	O
found	O
on	O
many	O
CPU	B-General_Concept
architectures	I-General_Concept
,	O
the	O
code	O
jumps	O
to	O
the	O
new	O
subroutine	O
and	O
pushes	O
the	O
next	O
address	O
onto	O
the	O
stack	O
.	O
</s>
<s>
Easy	O
and	O
fast	O
–	O
This	O
means	O
the	O
modification	O
process	B-Operating_System
is	O
fast	O
and	O
easy	O
.	O
</s>
<s>
When	O
modifying	O
the	O
existing	O
code	O
with	O
tools	O
such	O
as	O
Ollydbg	B-Application
,	O
the	O
added	O
functions	O
can	O
be	O
assembled	O
and	O
tested	O
without	O
any	O
external	O
dependencies	O
.	O
</s>
<s>
No	O
need	O
for	O
source	O
–	O
Using	O
code	B-Operating_System
caves	I-Operating_System
can	O
be	O
extremely	O
efficient	O
even	O
if	O
there	O
is	O
no	O
source	O
code	O
provided	O
for	O
the	O
programmer	O
.	O
</s>
<s>
This	O
means	O
that	O
there	O
may	O
not	O
be	O
an	O
existing	O
code	B-Operating_System
cave	I-Operating_System
in	O
the	O
existing	O
script	O
for	O
any	O
code	O
injection	O
due	O
to	O
the	O
lack	O
of	O
resources	O
provided	O
in	O
script	O
.	O
</s>
<s>
This	O
can	O
be	O
mitigated	O
by	O
the	O
use	O
of	O
shared	O
library	O
injectors	O
(	O
DLL	B-Operating_System
injection	I-Operating_System
 [ Windows ] 	O
or	O
LD_PRELOAD	O
 [ Linux ] 	O
)	O
such	O
that	O
the	O
injected	O
library	O
contains	O
already	O
compiled	O
code	O
and	O
existing	O
instructions	O
in	O
the	O
target	O
binary	O
are	O
simply	O
modified	O
to	O
use	O
it	O
.	O
</s>
<s>
pycave	O
:	O
Simple	O
tool	O
to	O
find	O
code	B-Operating_System
caves	I-Operating_System
in	O
Portable	O
Executable	O
(	O
PE	O
)	O
files	O
.	O
</s>
<s>
Ollydbg	B-Application
:	O
a	O
debugger	O
for	O
code	O
analysis	O
.	O
</s>
<s>
Cheat	B-Language
Engine	I-Language
:	O
a	O
powerful	O
tool	O
that	O
reads	O
process	B-Operating_System
memory	O
and	O
writes	O
process	B-Operating_System
memory	O
.	O
</s>
<s>
TSearch	O
:	O
a	O
powerful	O
tool	O
that	O
reads	O
process	B-Operating_System
memory	O
and	O
writes	O
process	B-Operating_System
memory	O
.	O
</s>
<s>
Like	O
Cheat	B-Language
Engine	I-Language
,	O
it	O
can	O
change	O
client-side	O
values	O
data	O
.	O
</s>
