<s>
Wi-Fi	B-Protocol
Protected	I-Protocol
Setup	I-Protocol
allows	O
the	O
owner	O
of	O
Wi-Fi	O
privileges	O
to	O
block	O
other	O
users	O
from	O
using	O
their	O
household	O
Wi-Fi	O
.	O
</s>
<s>
The	O
standard	O
emphasizes	O
usability	B-General_Concept
and	O
security	O
,	O
and	O
allows	O
four	O
modes	O
in	O
a	O
home	O
network	O
for	O
adding	O
a	O
new	O
device	O
to	O
the	O
network	O
:	O
</s>
<s>
PIN	O
method	O
In	O
which	O
a	O
PIN	O
has	O
to	O
be	O
read	O
from	O
either	O
a	O
sticker	O
or	O
display	O
on	O
the	O
new	O
wireless	B-Protocol
device	I-Protocol
.	O
</s>
<s>
This	O
PIN	O
must	O
then	O
be	O
entered	O
at	O
the	O
"	O
representant	O
"	O
of	O
the	O
network	O
,	O
usually	O
the	O
network	O
's	O
access	B-Device
point	I-Device
.	O
</s>
<s>
Alternately	O
,	O
a	O
PIN	O
provided	O
by	O
the	O
access	B-Device
point	I-Device
may	O
be	O
entered	O
into	O
the	O
new	O
device	O
.	O
</s>
<s>
Push	O
button	O
method	O
In	O
which	O
the	O
user	O
has	O
to	O
push	O
a	O
button	O
,	O
either	O
an	O
actual	O
or	O
virtual	O
one	O
,	O
on	O
both	O
the	O
access	B-Device
point	I-Device
and	O
the	O
new	O
wireless	O
client	O
device	O
.	O
</s>
<s>
Near-field	O
communication	O
method	O
In	O
which	O
the	O
user	O
has	O
to	O
bring	O
the	O
new	O
client	O
close	O
to	O
the	O
access	B-Device
point	I-Device
to	O
allow	O
a	O
near	O
field	O
communication	O
between	O
the	O
devices	O
.	O
</s>
<s>
NFC	O
Forumcompliant	O
RFID	B-Application
tags	I-Application
can	O
also	O
be	O
used	O
.	O
</s>
<s>
USB	O
method	O
In	O
which	O
the	O
user	O
uses	O
a	O
USB	O
flash	O
drive	O
to	O
transfer	O
data	O
between	O
the	O
new	O
client	O
device	O
and	O
the	O
network	O
's	O
access	B-Device
point	I-Device
.	O
</s>
<s>
The	O
last	O
two	O
modes	O
are	O
usually	O
referred	O
to	O
as	O
out-of-band	B-Protocol
methods	O
as	O
there	O
is	O
a	O
transfer	O
of	O
information	O
by	O
a	O
channel	O
other	O
than	O
the	O
Wi-Fi	O
channel	O
itself	O
.	O
</s>
<s>
Some	O
wireless	B-Device
access	I-Device
points	I-Device
have	O
a	O
dual-function	O
WPS	O
button	O
,	O
and	O
holding	O
this	O
button	O
down	O
for	O
a	O
shorter	O
or	O
longer	O
time	O
may	O
have	O
other	O
functions	O
,	O
such	O
as	O
factory-reset	O
or	O
toggling	O
WiFi	O
.	O
</s>
<s>
Some	O
manufacturers	O
,	O
such	O
as	O
Netgear	O
,	O
use	O
a	O
different	O
logo	O
and/or	O
name	O
for	O
Wi-Fi	B-Protocol
Protected	I-Protocol
Setup	I-Protocol
;	O
the	O
Wi-Fi	O
Alliance	O
recommends	O
the	O
use	O
of	O
the	O
Wi-Fi	B-Protocol
Protected	I-Protocol
Setup	I-Protocol
Identifier	O
Mark	O
on	O
the	O
hardware	O
button	O
for	O
this	O
function	O
.	O
</s>
<s>
Registrar	O
A	O
device	O
with	O
the	O
authority	O
to	O
issue	O
and	O
revoke	O
access	O
to	O
a	O
network	O
;	O
it	O
may	O
be	O
integrated	O
into	O
a	O
wireless	B-Device
access	I-Device
point	I-Device
(	O
AP	O
)	O
,	O
or	O
provided	O
as	O
a	O
separate	O
device	O
.	O
</s>
<s>
AP	O
An	O
access	B-Device
point	I-Device
functioning	O
as	O
a	O
proxy	O
between	O
a	O
registrar	O
and	O
an	O
enrollee	O
.	O
</s>
<s>
AP	O
with	O
integrated	O
registrar	O
capabilities	O
configures	O
an	O
enrollee	O
station	O
(	O
STA	B-Protocol
)	O
In	O
this	O
case	O
,	O
the	O
session	O
will	O
run	O
on	O
the	O
wireless	O
medium	O
as	O
a	O
series	O
of	O
EAP	B-Protocol
request/response	O
messages	O
,	O
ending	O
with	O
the	O
AP	O
disassociating	O
from	O
the	O
STA	B-Protocol
and	O
waiting	O
for	O
the	O
STA	B-Protocol
to	O
reconnect	O
with	O
its	O
new	O
configuration	O
(	O
handed	O
to	O
it	O
by	O
the	O
AP	O
just	O
before	O
)	O
.	O
</s>
<s>
Registrar	O
STA	B-Protocol
configures	O
the	O
AP	O
as	O
an	O
enrollee	O
This	O
case	O
is	O
subdivided	O
in	O
two	O
aspects	O
:	O
first	O
,	O
the	O
session	O
could	O
occur	O
on	O
either	O
a	O
wired	O
or	O
wireless	O
medium	O
,	O
and	O
second	O
,	O
the	O
AP	O
could	O
already	O
be	O
configured	O
by	O
the	O
time	O
the	O
registrar	O
found	O
it	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
a	O
wired	O
connection	O
between	O
the	O
devices	O
,	O
the	O
protocol	O
runs	O
over	O
Universal	B-Application
Plug	I-Application
and	I-Application
Play	I-Application
(	O
UPnP	B-Application
)	O
,	O
and	O
both	O
devices	O
will	O
have	O
to	O
support	O
UPnP	B-Application
for	O
that	O
purpose	O
.	O
</s>
<s>
When	O
running	O
over	O
UPnP	B-Application
,	O
a	O
shortened	O
version	O
of	O
the	O
protocol	O
is	O
run	O
(	O
only	O
two	O
messages	O
)	O
as	O
no	O
authentication	O
is	O
required	O
other	O
than	O
that	O
of	O
the	O
joined	O
wired	O
medium	O
.	O
</s>
<s>
UPnP	B-Application
is	O
intended	O
to	O
apply	O
only	O
to	O
a	O
wired	O
medium	O
,	O
while	O
actually	O
it	O
applies	O
to	O
any	O
interface	O
to	O
which	O
an	O
IP	O
connection	O
can	O
be	O
set	O
up	O
.	O
</s>
<s>
Thus	O
,	O
having	O
manually	O
set	O
up	O
a	O
wireless	O
connection	O
,	O
the	O
UPnP	B-Application
can	O
be	O
used	O
over	O
it	O
in	O
the	O
same	O
manner	O
as	O
with	O
the	O
wired	O
connection	O
.	O
</s>
<s>
Registrar	O
STA	B-Protocol
configures	O
enrollee	O
STA	B-Protocol
In	O
this	O
case	O
the	O
AP	O
stands	O
in	O
the	O
middle	O
and	O
acts	O
as	O
an	O
authenticator	O
,	O
meaning	O
it	O
only	O
proxies	O
the	O
relevant	O
messages	O
from	O
side	O
to	O
side	O
.	O
</s>
<s>
The	O
WPS	O
protocol	O
consists	O
of	O
a	O
series	O
of	O
EAP	B-Protocol
message	O
exchanges	O
that	O
are	O
triggered	O
by	O
a	O
user	O
action	O
,	O
relying	O
on	O
an	O
exchange	O
of	O
descriptive	O
information	O
that	O
should	O
precede	O
that	O
user	O
's	O
action	O
.	O
</s>
<s>
Other	O
than	O
purely	O
informative	O
type	B-Protocol
–	I-Protocol
length	I-Protocol
–	I-Protocol
values	I-Protocol
,	O
those	O
IEs	O
will	O
also	O
hold	O
the	O
possible	O
and	O
the	O
currently	O
deployed	O
configuration	O
methods	O
of	O
the	O
device	O
.	O
</s>
<s>
The	O
exact	O
stream	O
of	O
messages	O
may	O
change	O
when	O
configuring	O
different	O
kinds	O
of	O
devices	O
(	O
AP	O
or	O
STA	B-Protocol
)	O
,	O
or	O
when	O
using	O
different	O
physical	O
media	O
(	O
wired	O
or	O
wireless	O
)	O
.	O
</s>
<s>
Some	O
devices	O
with	O
dual-band	O
wireless	O
network	O
connectivity	O
do	O
not	O
allow	O
the	O
user	O
to	O
select	O
the	O
2.4GHz	O
or	O
5GHz	O
band	O
(	O
or	O
even	O
a	O
particular	O
radio	O
or	O
SSID	O
)	O
when	O
using	O
Wi-Fi	B-Protocol
Protected	I-Protocol
Setup	I-Protocol
,	O
unless	O
the	O
wireless	B-Device
access	I-Device
point	I-Device
has	O
separate	O
WPS	O
button	O
for	O
each	O
band	O
or	O
radio	O
;	O
however	O
,	O
a	O
number	O
of	O
later	O
wireless	O
routers	O
with	O
multiple	O
frequency	O
bands	O
and/or	O
radios	O
allow	O
the	O
establishment	O
of	O
a	O
WPS	O
session	O
for	O
a	O
specific	O
band	O
and/or	O
radio	O
for	O
connection	O
with	O
clients	O
which	O
cannot	O
have	O
the	O
SSID	O
or	O
band	O
(	O
e.g.	O
,	O
2.4/5GHz	O
)	O
explicitly	O
selected	O
by	O
the	O
user	O
on	O
the	O
client	O
for	O
connection	O
with	O
WPS	O
(	O
e.g.	O
</s>
<s>
Since	O
the	O
last	O
digit	O
is	O
a	O
checksum	B-Algorithm
of	O
the	O
previous	O
digits	O
,	O
there	O
are	O
seven	O
unknown	O
digits	O
in	O
each	O
PIN	O
,	O
yielding	O
107	O
=	O
10,000,000	O
possible	O
combinations	O
.	O
</s>
<s>
This	O
is	O
a	O
reduction	O
by	O
three	O
orders	B-Device
of	I-Device
magnitude	I-Device
from	O
the	O
number	O
of	O
PINs	O
that	O
would	O
be	O
required	O
to	O
be	O
tested	O
.	O
</s>
<s>
A	O
young	O
developer	B-Application
based	O
out	O
of	O
a	O
small	O
town	O
in	O
eastern	O
New	O
Mexico	O
created	O
a	O
tool	O
that	O
exploits	O
this	O
vulnerability	O
to	O
prove	O
that	O
the	O
attack	O
is	O
feasible	O
.	O
</s>
<s>
Firmware	B-Application
updates	O
have	O
been	O
released	O
for	O
some	O
of	O
these	O
devices	O
allowing	O
WPS	O
to	O
be	O
disabled	O
completely	O
.	O
</s>
<s>
Vendors	O
could	O
also	O
patch	O
the	O
vulnerability	O
by	O
adding	O
a	O
lock-down	O
period	O
if	O
the	O
Wi-Fi	B-Device
access	I-Device
point	I-Device
detects	O
a	O
brute-force	O
attack	O
in	O
progress	O
,	O
which	O
disables	O
the	O
PIN	O
method	O
for	O
long	O
enough	O
to	O
make	O
the	O
attack	O
impractical	O
.	O
</s>
<s>
Since	O
both	O
the	O
client	O
and	O
access	B-Device
point	I-Device
(	O
enrollee	O
and	O
registrar	O
,	O
respectively	O
)	O
need	O
to	O
prove	O
they	O
know	O
the	O
PIN	O
to	O
make	O
sure	O
the	O
client	O
is	O
not	O
connecting	O
to	O
a	O
rogue	O
AP	O
,	O
the	O
attacker	O
already	O
has	O
two	O
hashes	O
that	O
contain	O
each	O
half	O
of	O
the	O
PIN	O
,	O
and	O
all	O
they	O
need	O
is	O
to	O
brute-force	O
the	O
actual	O
PIN	O
.	O
</s>
<s>
The	O
access	B-Device
point	I-Device
sends	O
two	O
hashes	O
,	O
E-Hash1	O
and	O
E-Hash2	O
,	O
to	O
the	O
client	O
,	O
proving	O
that	O
it	O
also	O
knows	O
the	O
PIN	O
.	O
</s>
<s>
All	O
WPS	O
methods	O
are	O
vulnerable	O
to	O
usage	O
by	O
an	O
unauthorized	O
user	O
if	O
the	O
wireless	B-Device
access	I-Device
point	I-Device
is	O
not	O
kept	O
in	O
a	O
secure	O
area	O
.	O
</s>
<s>
Many	O
wireless	B-Device
access	I-Device
points	I-Device
have	O
security	O
information	O
(	O
if	O
it	O
is	O
factory-secured	O
)	O
and	O
the	O
WPS	O
PIN	O
printed	O
on	O
them	O
;	O
this	O
PIN	O
is	O
also	O
often	O
found	O
in	O
the	O
configuration	O
menus	O
of	O
the	O
wireless	B-Device
access	I-Device
point	I-Device
.	O
</s>
<s>
If	O
this	O
PIN	O
cannot	O
be	O
changed	O
or	O
disabled	O
,	O
the	O
only	O
remedy	O
is	O
to	O
get	O
a	O
firmware	B-Application
update	O
to	O
enable	O
the	O
PIN	O
to	O
be	O
changed	O
,	O
or	O
to	O
replace	O
the	O
wireless	B-Device
access	I-Device
point	I-Device
.	O
</s>
<s>
A	O
wireless	O
passphrase	O
can	O
be	O
extracted	O
using	O
WPS	O
under	O
Windows	B-Application
Vista	I-Application
and	O
newer	O
versions	O
of	O
Windows	O
,	O
under	O
administrative	B-Application
privileges	I-Application
by	O
connecting	O
with	O
this	O
method	O
then	O
bringing	O
up	O
the	O
properties	O
for	O
this	O
wireless	O
network	O
and	O
clicking	O
on	O
"	O
show	O
characters	O
"	O
.	O
</s>
<s>
Within	O
most	O
Linux	O
desktop	O
and	O
Unix	B-Application
distributions	O
(	O
like	O
Ubuntu	B-Operating_System
)	O
,	O
all	O
network	O
connections	O
and	O
their	O
details	O
are	O
visible	O
to	O
a	O
regular	O
user	O
,	O
including	O
the	O
password	O
obtained	O
through	O
WPS	O
.	O
</s>
<s>
Furthermore	O
,	O
root	B-Application
(	O
aka	O
admin	O
)	O
can	O
always	O
access	O
all	O
network	O
details	O
through	O
terminal	O
,	O
i.e.	O
</s>
<s>
even	O
if	O
there	O
is	O
no	O
window	B-Application
manager	I-Application
active	O
for	O
regular	O
users	O
.	O
</s>
<s>
A	O
simple	O
exploit	O
in	O
the	O
Intel	O
PROset	O
wireless	O
client	O
utility	O
can	O
reveal	O
the	O
wireless	O
passphrase	O
when	O
WPS	O
is	O
used	O
,	O
after	O
a	O
simple	O
move	O
of	O
the	O
dialog	O
box	O
which	O
asks	O
if	O
you	O
want	O
to	O
reconfigure	O
this	O
access	B-Device
point	I-Device
.	O
</s>
