<s>
Browser	B-Protocol
security	I-Protocol
is	O
the	O
application	O
of	O
Internet	B-Application
security	I-Application
to	O
web	B-Application
browsers	I-Application
in	O
order	O
to	O
protect	O
networked	B-Architecture
data	O
and	O
computer	O
systems	O
from	O
breaches	O
of	O
privacy	O
or	O
malware	O
.	O
</s>
<s>
Security	O
exploits	O
of	O
browsers	B-Application
often	O
use	O
JavaScript	B-Language
,	O
sometimes	O
with	O
cross-site	O
scripting	O
(	O
XSS	O
)	O
with	O
a	O
secondary	O
payload	O
using	O
Adobe	B-Operating_System
Flash	I-Operating_System
.	O
</s>
<s>
Security	O
exploits	O
can	O
also	O
take	O
advantage	O
of	O
vulnerabilities	O
(	O
security	O
holes	O
)	O
that	O
are	O
commonly	O
exploited	O
in	O
all	O
browsers	B-Application
(	O
including	O
Mozilla	B-Application
Firefox	I-Application
,	O
Google	B-Application
Chrome	I-Application
,	O
Opera	B-Application
,	O
Microsoft	B-Application
Internet	I-Application
Explorer	I-Application
,	O
and	O
Safari	B-Application
)	O
.	O
</s>
<s>
Web	B-Application
browsers	I-Application
can	O
be	O
breached	O
in	O
one	O
or	O
more	O
of	O
the	O
following	O
ways	O
:	O
</s>
<s>
The	O
browser	B-Application
may	O
not	O
be	O
aware	O
of	O
any	O
of	O
the	O
breaches	O
above	O
and	O
may	O
show	O
user	O
a	O
safe	O
connection	O
is	O
made	O
.	O
</s>
<s>
Whenever	O
a	O
browser	B-Application
communicates	O
with	O
a	O
website	O
,	O
the	O
website	O
,	O
as	O
part	O
of	O
that	O
communication	O
,	O
collects	O
some	O
information	O
about	O
the	O
browser	B-Application
(	O
in	O
order	O
to	O
process	O
the	O
formatting	O
of	O
the	O
page	O
to	O
be	O
delivered	O
,	O
if	O
nothing	O
else	O
)	O
.	O
</s>
<s>
If	O
malicious	O
code	O
has	O
been	O
inserted	O
into	O
the	O
website	O
's	O
content	O
,	O
or	O
in	O
a	O
worst-case	O
scenario	O
,	O
if	O
that	O
website	O
has	O
been	O
specifically	O
designed	O
to	O
host	O
malicious	O
code	O
,	O
then	O
vulnerabilities	O
specific	O
to	O
a	O
particular	O
browser	B-Application
can	O
allow	O
this	O
malicious	O
code	O
to	O
run	O
processes	O
within	O
the	O
browser	B-Application
application	O
in	O
unintended	O
ways	O
(	O
and	O
remember	O
,	O
one	O
of	O
the	O
bits	O
of	O
information	O
that	O
a	O
website	O
collects	O
from	O
a	O
browser	B-Application
communication	O
is	O
the	O
browser	B-Application
's	O
identity	O
-	O
allowing	O
specific	O
vulnerabilities	O
to	O
be	O
exploited	O
)	O
.	O
</s>
<s>
Once	O
an	O
attacker	O
is	O
able	O
to	O
run	O
processes	O
on	O
the	O
visitor	O
's	O
machine	O
,	O
then	O
exploiting	O
known	O
security	O
vulnerabilities	O
can	O
allow	O
the	O
attacker	O
to	O
gain	O
privileged	O
access	O
(	O
if	O
the	O
browser	B-Application
is	O
n't	O
already	O
running	O
with	O
privileged	O
access	O
)	O
to	O
the	O
"	O
infected	O
"	O
system	O
in	O
order	O
to	O
perform	O
an	O
even	O
greater	O
variety	O
of	O
malicious	O
processes	O
and	O
activities	O
on	O
the	O
machine	O
or	O
even	O
the	O
victim	O
's	O
whole	O
network	O
.	O
</s>
<s>
Breaches	O
of	O
web	B-Protocol
browser	I-Protocol
security	I-Protocol
are	O
usually	O
for	O
the	O
purpose	O
of	O
bypassing	O
protections	O
to	O
display	O
pop-up	O
advertising	O
collecting	O
personally	O
identifiable	O
information	O
(	O
PII	O
)	O
for	O
either	O
Internet	O
marketing	O
or	O
identity	O
theft	O
,	O
website	O
tracking	O
or	O
web	O
analytics	O
about	O
a	O
user	O
against	O
their	O
will	O
using	O
tools	O
such	O
as	O
web	B-Protocol
bugs	I-Protocol
,	O
Clickjacking	O
,	O
Likejacking	O
(	O
where	O
Facebook	B-Application
's	O
like	O
button	O
is	O
targeted	O
)	O
,	O
HTTP	B-Application
cookies	I-Application
,	O
zombie	B-Application
cookies	I-Application
or	O
Flash	B-Operating_System
cookies	I-Operating_System
(	O
Local	B-Operating_System
Shared	I-Operating_System
Objects	I-Operating_System
or	O
LSOs	O
)	O
;	O
installing	O
adware	O
,	O
viruses	O
,	O
spyware	O
such	O
as	O
Trojan	O
horses	O
(	O
to	O
gain	O
access	O
to	O
users	O
 '	O
personal	B-Device
computers	I-Device
via	O
cracking	O
)	O
or	O
other	O
malware	O
including	O
online	B-Application
banking	I-Application
theft	O
using	O
man-in-the-browser	B-Protocol
attacks	O
.	O
</s>
<s>
In	O
depth	O
study	O
of	O
vulnerabilities	O
in	O
Chromium	B-Language
web-browser	B-Application
indicates	O
that	O
,	O
Improper	O
Input	O
Validation	O
(	O
CWE-20	O
)	O
and	O
Improper	O
Access	O
Control	O
(	O
CWE-284	O
)	O
are	O
the	O
most	O
occurring	O
root	O
causes	O
for	O
security	O
vulnerabilities	O
.	O
</s>
<s>
Furthermore	O
,	O
among	O
vulnerabilities	O
examined	O
at	O
the	O
time	O
of	O
this	O
study	O
,	O
106	O
vulnerabilities	O
occurred	O
in	O
Chromium	B-Language
because	O
of	O
reusing	O
or	O
importing	O
vulnerable	O
versions	O
of	O
third	O
party	O
libraries	O
.	O
</s>
<s>
Vulnerabilities	O
in	O
the	O
web	B-Application
browser	I-Application
software	O
itself	O
can	O
be	O
minimized	O
by	O
keeping	O
browser	B-Application
software	O
updated	O
,	O
but	O
will	O
not	O
be	O
sufficient	O
if	O
the	O
underlying	O
operating	B-General_Concept
system	I-General_Concept
is	O
compromised	O
,	O
for	O
example	O
,	O
by	O
a	O
rootkit	O
.	O
</s>
<s>
Some	O
subcomponents	O
of	O
browsers	B-Application
such	O
as	O
scripting	O
,	O
add-ons	O
,	O
and	O
cookies	B-Application
are	O
particularly	O
vulnerable	O
(	O
"	O
the	O
confused	O
deputy	O
problem	O
"	O
)	O
and	O
also	O
need	O
to	O
be	O
addressed	O
.	O
</s>
<s>
Following	O
the	O
principle	O
of	O
defence	O
in	O
depth	O
,	O
a	O
fully	O
patched	O
and	O
correctly	O
configured	O
browser	B-Application
may	O
not	O
be	O
sufficient	O
to	O
ensure	O
that	O
browser-related	O
security	O
issues	O
cannot	O
occur	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
rootkit	O
can	O
capture	O
keystrokes	O
while	O
someone	O
logs	O
into	O
a	O
banking	O
website	O
,	O
or	O
carry	O
out	O
a	O
man-in-the-middle	O
attack	O
by	O
modifying	O
network	O
traffic	O
to	O
and	O
from	O
a	O
web	B-Application
browser	I-Application
.	O
</s>
<s>
DNS	B-Protocol
hijacking	I-Protocol
or	O
DNS	B-Protocol
spoofing	O
may	O
be	O
used	O
to	O
return	O
false	O
positives	O
for	O
mistyped	O
website	O
names	O
,	O
or	O
to	O
subvert	O
search	O
results	O
for	O
popular	O
search	O
engines	O
.	O
</s>
<s>
Malware	O
such	O
as	O
RSPlug	B-Application
simply	O
modifies	O
a	O
system	O
's	O
configuration	O
to	O
point	O
at	O
rogue	B-Protocol
DNS	I-Protocol
servers	I-Protocol
.	O
</s>
<s>
Browsers	B-Application
can	O
use	O
more	O
secure	O
methods	O
of	O
network	O
communication	O
to	O
help	O
prevent	O
some	O
of	O
these	O
attacks	O
:	O
</s>
<s>
DNS	B-Protocol
:	O
DNSSec	B-Protocol
and	O
DNSCrypt	B-Protocol
,	O
for	O
example	O
with	O
non-default	O
DNS	B-Protocol
servers	I-Protocol
such	O
as	O
Google	B-Protocol
Public	I-Protocol
DNS	I-Protocol
or	O
OpenDNS	B-Protocol
.	O
</s>
<s>
HTTP:	O
HTTP	B-Protocol
Secure	I-Protocol
and	O
SPDY	B-Protocol
with	O
digitally	O
signed	O
public	O
key	O
certificates	O
or	O
Extended	B-Application
Validation	I-Application
Certificates	I-Application
.	O
</s>
<s>
Perimeter	O
defenses	O
,	O
typically	O
through	O
firewalls	O
and	O
the	O
use	O
of	O
filtering	B-Protocol
proxy	B-Application
servers	I-Application
that	O
block	O
malicious	O
websites	O
and	O
perform	O
antivirus	O
scans	O
of	O
any	O
file	O
downloads	O
,	O
are	O
commonly	O
implemented	O
as	O
a	O
best	O
practice	O
in	O
large	O
organizations	O
to	O
block	O
malicious	O
network	O
traffic	O
before	O
it	O
reaches	O
a	O
browser	B-Application
.	O
</s>
<s>
The	O
topic	O
of	O
browser	B-Protocol
security	I-Protocol
has	O
grown	O
to	O
the	O
point	O
of	O
spawning	O
the	O
creation	O
of	O
entire	O
organizations	O
,	O
such	O
as	O
The	O
Browser	B-Application
Exploitation	O
Framework	O
Project	O
,	O
creating	O
platforms	O
to	O
collect	O
tools	O
to	O
breach	O
browser	B-Protocol
security	I-Protocol
,	O
ostensibly	O
in	O
order	O
to	O
test	O
browsers	B-Application
and	O
network	O
systems	O
for	O
vulnerabilities	O
.	O
</s>
<s>
Although	O
not	O
part	O
of	O
the	O
browser	B-Application
per	O
se	O
,	O
browser	B-Protocol
plugins	I-Protocol
and	O
extensions	O
extend	O
the	O
attack	O
surface	O
,	O
exposing	O
vulnerabilities	O
in	O
Adobe	B-Operating_System
Flash	I-Operating_System
Player	O
,	O
Adobe	O
(	O
Acrobat	O
)	O
Reader	O
,	O
Java	B-Application
plugin	I-Application
,	O
and	O
ActiveX	B-Application
that	O
are	O
commonly	O
exploited	O
.	O
</s>
<s>
Researchers	O
have	O
extensively	O
studied	O
the	O
security	O
architecture	O
of	O
various	O
web-browsers	B-Application
in	O
particular	O
those	O
relying	O
on	O
plug-and-play	O
designs	O
.	O
</s>
<s>
Malware	O
may	O
also	O
be	O
implemented	O
as	O
a	O
browser	B-Protocol
extension	I-Protocol
,	O
such	O
as	O
a	O
browser	B-Application
helper	I-Application
object	I-Application
in	O
the	O
case	O
of	O
Internet	B-Application
Explorer	I-Application
.	O
</s>
<s>
In	O
various	O
other	O
exploits	O
websites	O
which	O
were	O
designed	O
to	O
look	O
authentic	O
and	O
included	O
rogue	O
'	O
update	O
Adobe	B-Operating_System
Flash	I-Operating_System
 '	O
popups	O
designed	O
as	O
visual	O
cues	O
to	O
download	O
malware	O
payloads	O
in	O
their	O
place	O
.	O
</s>
<s>
Some	O
browsers	B-Application
like	O
Google	B-Application
Chrome	I-Application
and	O
Mozilla	B-Application
Firefox	I-Application
can	O
block	O
—	O
or	O
warn	O
users	O
of	O
—	O
insecure	O
plugins	B-Application
.	O
</s>
<s>
An	O
August	O
2009	O
study	O
by	O
the	O
Social	O
Science	O
Research	O
Network	O
found	O
that	O
50%	O
of	O
websites	O
using	O
Flash	B-Operating_System
were	O
also	O
employing	O
Flash	B-Operating_System
cookies	I-Operating_System
,	O
yet	O
privacy	O
policies	O
rarely	O
disclosed	O
them	O
,	O
and	O
user	O
controls	O
for	O
privacy	O
preferences	O
were	O
lacking	O
.	O
</s>
<s>
Most	O
browsers	B-Application
 '	O
cache	B-Protocol
and	O
history	O
delete	O
functions	O
do	O
not	O
affect	O
Flash	B-Operating_System
Player	O
's	O
writing	O
Local	B-Operating_System
Shared	I-Operating_System
Objects	I-Operating_System
to	O
its	O
own	O
cache	B-Protocol
,	O
and	O
the	O
user	O
community	O
is	O
much	O
less	O
aware	O
of	O
the	O
existence	O
and	O
function	O
of	O
Flash	B-Operating_System
cookies	I-Operating_System
than	O
HTTP	B-Application
cookies	I-Application
.	O
</s>
<s>
Thus	O
,	O
users	O
having	O
deleted	O
HTTP	B-Application
cookies	I-Application
and	O
purged	O
browser	B-Application
history	O
files	O
and	O
caches	O
may	O
believe	O
that	O
they	O
have	O
purged	O
all	O
tracking	O
data	O
from	O
their	O
computers	O
while	O
in	O
fact	O
Flash	B-Operating_System
browsing	O
history	O
remains	O
.	O
</s>
<s>
As	O
well	O
as	O
manual	O
removal	O
,	O
the	O
BetterPrivacy	O
add-on	O
for	O
Firefox	B-Application
can	O
remove	O
Flash	B-Operating_System
cookies	I-Operating_System
.	O
</s>
<s>
Adblock	B-Application
Plus	I-Application
can	O
be	O
used	O
to	O
filter	O
out	O
specific	O
threats	O
and	O
Flashblock	B-Operating_System
can	O
be	O
used	O
to	O
give	O
an	O
option	O
before	O
allowing	O
content	O
on	O
otherwise	O
trusted	O
sites	O
.	O
</s>
<s>
Charlie	O
Miller	O
recommended	O
"	O
not	O
to	O
install	O
Flash	B-Operating_System
"	O
at	O
the	O
computer	O
security	O
conference	O
CanSecWest	O
.	O
</s>
<s>
Several	O
other	O
security	O
experts	O
also	O
recommend	O
to	O
either	O
not	O
install	O
Adobe	B-Operating_System
Flash	I-Operating_System
Player	O
or	O
to	O
block	O
it	O
.	O
</s>
<s>
If	O
HTTPS	B-Protocol
is	O
used	O
,	O
then	O
encryption	O
is	O
used	O
to	O
secure	O
against	O
attackers	O
with	O
access	O
to	O
the	O
network	O
from	O
changing	O
the	O
page	O
contents	O
en	O
route	O
.	O
</s>
<s>
youtube.com	O
)	O
,	O
the	O
user	O
should	O
always	O
check	O
that	O
the	O
address	O
bar	O
says	O
"	O
https://accounts.google.com	O
"	O
before	O
inputting	O
their	O
password	O
.	O
</s>
<s>
An	O
un-compromised	O
browser	B-Application
guarantees	O
that	O
the	O
address	O
bar	O
is	O
correct	O
.	O
</s>
<s>
This	O
guarantee	O
is	O
one	O
reason	O
why	O
browsers	B-Application
will	O
generally	O
display	O
a	O
warning	O
when	O
entering	O
fullscreen	O
mode	O
,	O
on	O
top	O
of	O
where	O
the	O
address	O
bar	O
would	O
normally	O
be	O
,	O
so	O
that	O
a	O
fullscreen	O
website	O
cannot	O
make	O
a	O
fake	O
browser	B-Application
user	O
interface	O
with	O
a	O
fake	O
address	O
bar	O
.	O
</s>
<s>
There	O
have	O
been	O
attempts	O
to	O
market	O
hardware-based	O
browsers	B-Application
running	O
from	O
non-writable	O
,	O
read-only	O
file	O
systems	O
.	O
</s>
<s>
The	O
first	O
such	O
device	O
was	O
the	O
ZeusGard	O
Secure	O
Hardware	O
Browser	B-Application
,	O
released	O
in	O
late	O
2013	O
.	O
</s>
<s>
Another	O
device	O
,	O
the	O
iCloak®	O
Stik	O
from	O
provides	O
a	O
complete	O
Live	O
OS	O
which	O
completely	O
replaces	O
the	O
computer	O
's	O
entire	O
operating	B-General_Concept
system	I-General_Concept
and	O
offers	O
two	O
web	B-Application
browsers	I-Application
from	O
the	O
read-only	O
system	O
.	O
</s>
<s>
With	O
iCloak	O
they	O
provide	O
the	O
Tor	O
browser	B-Application
for	O
Anonymous	O
browsing	O
as	O
well	O
as	O
a	O
regular	O
Firefox	B-Application
browser	I-Application
for	O
non-anonymous	O
browsing	O
.	O
</s>
<s>
Any	O
non-secured	O
web	O
traffic	O
(	O
not	O
using	O
https	B-Protocol
,	O
for	O
example	O
)	O
,	O
could	O
still	O
be	O
subject	O
to	O
man-in-the-middle	O
alteration	O
or	O
other	O
network	O
traffic-based	O
manipulations	O
.	O
</s>
<s>
LiveCDs	O
,	O
which	O
run	O
an	O
operating	B-General_Concept
system	I-General_Concept
from	O
a	O
non-writable	O
source	O
,	O
typically	O
come	O
with	O
Web	B-Application
browsers	I-Application
as	O
part	O
of	O
their	O
default	O
image	O
.	O
</s>
<s>
If	O
the	O
original	O
LiveCD	O
image	O
is	O
free	O
of	O
malware	O
,	O
all	O
of	O
the	O
software	O
used	O
,	O
including	O
the	O
Web	B-Application
browser	I-Application
,	O
will	O
load	O
free	O
of	O
malware	O
every	O
time	O
the	O
LiveCD	O
image	O
is	O
booted	O
.	O
</s>
<s>
without	O
administrator	O
privileges	O
)	O
limits	O
the	O
ability	O
of	O
a	O
security	O
exploit	O
in	O
a	O
web	B-Application
browser	I-Application
from	O
compromising	O
the	O
whole	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Internet	B-Protocol
Explorer	I-Protocol
4	I-Protocol
and	O
later	O
allows	O
the	O
blacklisting	O
and	O
whitelisting	O
of	O
ActiveX	B-Application
controls	I-Application
,	O
add-ons	O
and	O
browser	B-Protocol
extensions	I-Protocol
in	O
various	O
ways	O
.	O
</s>
<s>
Internet	B-Application
Explorer	I-Application
7	I-Application
added	O
"	O
protected	O
mode	O
"	O
,	O
a	O
technology	O
that	O
hardens	O
the	O
browser	B-Application
through	O
the	O
application	O
of	O
a	O
security	O
sandboxing	O
feature	O
of	O
Windows	B-Application
Vista	I-Application
called	O
Mandatory	O
Integrity	O
Control	O
.	O
</s>
<s>
Google	B-Application
Chrome	I-Application
provides	O
a	O
sandbox	O
to	O
limit	O
web	O
page	O
access	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Suspected	O
malware	O
sites	O
reported	O
to	O
Google	O
,	O
and	O
confirmed	O
by	O
Google	O
,	O
are	O
flagged	O
as	O
hosting	O
malware	O
in	O
certain	O
browsers	B-Application
.	O
</s>
<s>
There	O
are	O
third-party	O
extensions	O
and	O
plugins	B-Application
available	O
to	O
harden	O
even	O
the	O
latest	O
browsers	B-Application
,	O
and	O
some	O
for	O
older	O
browsers	B-Application
and	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Whitelist-based	O
software	O
such	O
as	O
NoScript	B-Operating_System
can	O
block	O
JavaScript	B-Language
and	O
Adobe	B-Operating_System
Flash	I-Operating_System
which	O
is	O
used	O
for	O
most	O
attacks	O
on	O
privacy	O
,	O
allowing	O
users	O
to	O
choose	O
only	O
sites	O
they	O
know	O
are	O
safe	O
-	O
AdBlock	B-Application
Plus	I-Application
also	O
uses	O
whitelist	O
ad	O
filtering	B-Protocol
rules	O
subscriptions	O
,	O
though	O
both	O
the	O
software	O
itself	O
and	O
the	O
filtering	B-Protocol
list	O
maintainers	O
have	O
come	O
under	O
controversy	O
for	O
by-default	O
allowing	O
some	O
sites	O
to	O
pass	O
the	O
pre-set	O
filters	O
.	O
</s>
<s>
The	O
US-CERT	O
recommends	O
to	O
block	O
Flash	B-Operating_System
using	O
NoScript	B-Operating_System
.	O
</s>
<s>
Modern	O
web	B-Application
browsers	I-Application
undergo	O
extensive	O
fuzzing	O
to	O
uncover	O
vulnerabilities	O
.	O
</s>
<s>
The	O
Chromium	B-Language
code	O
of	O
Google	B-Application
Chrome	I-Application
is	O
continuously	O
fuzzed	O
by	O
the	O
Chrome	B-Application
Security	O
Team	O
with	O
15,000	O
cores	O
.	O
</s>
<s>
For	O
Microsoft	B-Application
Edge	I-Application
and	O
Internet	B-Application
Explorer	I-Application
,	O
Microsoft	O
performed	O
fuzzed	O
testing	O
with	O
670	O
machine-years	O
during	O
product	O
development	O
,	O
generating	O
more	O
than	O
400	O
billion	O
DOM	O
manipulations	O
from	O
1	O
billion	O
HTML	O
files	O
.	O
</s>
