<s>
Hooksafe	B-General_Concept
is	O
a	O
hypervisor-based	O
lightweight	O
system	O
that	O
protects	O
an	O
operating	O
system	O
's	O
kernel	B-Operating_System
hooks	O
from	O
rootkit	O
attacks	O
.	O
</s>
<s>
It	O
prevents	O
thousands	O
of	O
kernel	B-Operating_System
hooks	O
in	O
the	O
guest	O
operating	O
system	O
from	O
being	O
hijacked	O
.	O
</s>
<s>
This	O
is	O
achieved	O
by	O
making	O
a	O
shadow	O
copy	O
of	O
all	O
the	O
kernel	B-Operating_System
hooks	O
at	O
one	O
central	O
place	O
and	O
adding	O
an	O
indirection	O
layer	O
on	O
it	O
to	O
regulate	O
attempts	O
to	O
access	O
the	O
hooks	O
.	O
</s>
<s>
A	O
prototype	O
of	O
Hooksafe	B-General_Concept
was	O
used	O
on	O
a	O
Linux	O
guest	O
and	O
protected	O
nearly	O
6000	O
kernel	B-Operating_System
hooks	O
.	O
</s>
<s>
It	O
focuses	O
on	O
protecting	O
kernel	B-Operating_System
control	O
data	O
that	O
are	O
function	O
pointers	O
.	O
</s>
<s>
Prior	O
rootkit	O
thwarting	O
systems	O
include	O
:	O
Panorama	O
,	O
Hookfinder	O
and	O
systems	O
focused	O
on	O
analyzing	O
rootkit	O
behavior	O
,	O
Copilot	O
,	O
VMwatcher	O
and	O
systems	O
that	O
detect	O
rootkits	O
based	O
on	O
symptoms	O
,	O
Patagonix	O
,	O
NICKLE	O
and	O
systems	O
aimed	O
to	O
preserve	O
kernel	B-Operating_System
code	B-General_Concept
integrity	I-General_Concept
by	O
preventing	O
malicious	O
rootkit	O
code	O
from	O
executing	O
.	O
</s>
