<s>
China	B-Protocol
Chopper	I-Protocol
is	O
a	O
web	B-Protocol
shell	I-Protocol
approximately	O
4	O
kilobytes	O
in	O
size	O
,	O
first	O
discovered	O
in	O
2012	O
.	O
</s>
<s>
This	O
web	B-Protocol
shell	I-Protocol
is	O
commonly	O
used	O
by	O
malicious	O
Chinese	O
actors	O
,	O
including	O
advanced	O
persistent	O
threat	O
(	O
APT	O
)	O
groups	O
,	O
to	O
remotely	O
control	O
web	B-Application
servers	I-Application
.	O
</s>
<s>
This	O
web	B-Protocol
shell	I-Protocol
has	O
two	O
parts	O
,	O
the	O
client	O
interface	O
(	O
an	O
executable	B-Application
file	I-Application
)	O
and	O
the	O
receiver	O
host	O
file	O
on	O
the	O
compromised	O
web	B-Application
server	I-Application
.	O
</s>
<s>
China	B-Protocol
Chopper	I-Protocol
has	O
many	O
commands	O
and	O
control	O
features	O
such	O
as	O
a	O
password	O
brute-force	O
attack	O
option	O
,	O
code	O
obfuscation	O
,	O
file	O
and	O
database	O
management	O
and	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
China	B-Protocol
Chopper	I-Protocol
was	O
used	O
in	O
attacks	O
against	O
eight	O
Australian	O
web	O
hosting	O
providers	O
which	O
were	O
compromised	O
due	O
to	O
their	O
use	O
of	O
an	O
unsupported	O
operating	O
system	O
(	O
Windows	B-Device
Server	I-Device
2008	I-Device
)	O
.	O
</s>
<s>
Hackers	B-Application
connected	O
the	O
web	B-Application
servers	I-Application
to	O
a	O
Monero	B-Protocol
mining	B-Protocol
pool	I-Protocol
,	O
by	O
which	O
they	O
mined	O
about	O
3868	O
AUD	O
worth	O
of	O
Monero	B-Protocol
.	O
</s>
<s>
In	O
2021	O
,	O
a	O
version	O
of	O
the	O
web	B-Protocol
shell	I-Protocol
programmed	O
in	O
JScript	B-Language
was	O
used	O
by	O
Advanced	O
Persistent	O
Threat	O
group	O
Hafnium	O
to	O
exploit	O
four	O
zero-day	O
vulnerabilities	O
in	O
Microsoft	B-Operating_System
Exchange	I-Operating_System
Server	I-Operating_System
,	O
in	O
the	O
2021	B-Application
Microsoft	I-Application
Exchange	I-Application
Server	I-Application
data	I-Application
breach	I-Application
.	O
</s>
<s>
This	O
web	B-Protocol
shell	I-Protocol
was	O
dropped	O
when	O
one	O
of	O
these	O
vulnerabilities	O
was	O
exploited	O
,	O
allowing	O
attackers	O
to	O
upload	O
a	O
program	O
which	O
ran	O
with	O
administrator	O
privileges	O
.	O
</s>
<s>
With	O
only	O
the	O
address	O
of	O
the	O
.aspx	B-Application
file	O
containing	O
the	O
script	O
,	O
a	O
HTTP	B-Protocol
POST	I-Protocol
request	I-Protocol
could	O
be	O
made	O
to	O
the	O
script	O
with	O
just	O
a	O
command	O
in	O
the	O
request	O
,	O
causing	O
the	O
script	O
to	O
execute	O
the	O
command	O
immediately	O
using	O
the	O
JScript	B-Language
'	O
eval	O
 '	O
function	O
,	O
allowing	O
attackers	O
to	O
run	O
arbitrary	O
code	O
on	O
the	O
server	O
.	O
</s>
