<s>
CRIME	O
(	O
Compression	O
Ratio	O
Info-leak	O
Made	O
Easy	O
)	O
is	O
a	O
security	O
vulnerability	O
in	O
HTTPS	B-Protocol
and	O
SPDY	B-Protocol
protocols	O
that	O
utilize	O
compression	O
,	O
which	O
can	O
leak	O
the	O
content	O
of	O
secret	O
web	B-Application
cookies	I-Application
.	O
</s>
<s>
When	O
used	O
to	O
recover	O
the	O
content	O
of	O
secret	O
authentication	B-Application
cookies	I-Application
,	O
it	O
allows	O
an	O
attacker	O
to	O
perform	O
session	B-Protocol
hijacking	I-Protocol
on	O
an	O
authenticated	O
web	O
session	O
,	O
allowing	O
the	O
launching	O
of	O
further	O
attacks	O
.	O
</s>
<s>
It	O
relies	O
on	O
the	O
attacker	O
being	O
able	O
to	O
observe	O
the	O
size	O
of	O
the	O
ciphertext	O
sent	O
by	O
the	O
browser	B-Application
while	O
at	O
the	O
same	O
time	O
inducing	O
the	O
browser	B-Application
to	O
make	O
multiple	O
carefully	O
crafted	O
web	O
connections	O
to	O
the	O
target	O
site	O
.	O
</s>
<s>
The	O
attacker	O
then	O
observes	O
the	O
change	O
in	O
size	O
of	O
the	O
compressed	O
request	O
payload	O
,	O
which	O
contains	O
both	O
the	O
secret	O
cookie	B-Application
that	O
is	O
sent	O
by	O
the	O
browser	B-Application
only	O
to	O
the	O
target	O
site	O
,	O
and	O
variable	O
content	O
created	O
by	O
the	O
attacker	O
,	O
as	O
the	O
variable	O
content	O
is	O
altered	O
.	O
</s>
<s>
Divide	B-Algorithm
and	I-Algorithm
conquer	I-Algorithm
techniques	O
can	O
then	O
be	O
used	O
to	O
home	O
in	O
on	O
the	O
true	O
secret	O
content	O
in	O
a	O
relatively	O
small	O
number	O
of	O
probe	O
attempts	O
that	O
is	O
a	O
small	O
multiple	O
of	O
the	O
number	O
of	O
secret	O
bytes	O
to	O
be	O
recovered	O
.	O
</s>
<s>
The	O
exploit	O
was	O
due	O
to	O
be	O
revealed	O
in	O
full	O
at	O
the	O
2012	O
ekoparty	B-General_Concept
security	O
conference	O
.	O
</s>
<s>
Rizzo	O
and	O
Duong	O
presented	O
CRIME	O
as	O
a	O
general	O
attack	O
that	O
works	O
effectively	O
against	O
a	O
large	O
number	O
of	O
protocols	O
,	O
including	O
but	O
not	O
limited	O
to	O
SPDY	B-Protocol
(	O
which	O
always	O
compresses	O
request	O
headers	O
)	O
,	O
TLS	O
(	O
which	O
may	O
compress	O
records	O
)	O
and	O
HTTP	B-Protocol
(	O
which	O
may	O
compress	O
responses	O
)	O
.	O
</s>
<s>
CRIME	O
can	O
be	O
defeated	O
by	O
preventing	O
the	O
use	O
of	O
compression	O
,	O
either	O
at	O
the	O
client	O
end	O
,	O
by	O
the	O
browser	B-Application
disabling	O
the	O
compression	O
of	O
SPDY	B-Protocol
requests	O
,	O
or	O
by	O
the	O
website	O
preventing	O
the	O
use	O
of	O
data	O
compression	O
on	O
such	O
transactions	O
using	O
the	O
protocol	O
negotiation	O
features	O
of	O
the	O
TLS	O
protocol	O
.	O
</s>
<s>
,	O
the	O
CRIME	O
exploit	O
against	O
SPDY	B-Protocol
and	O
TLS-level	O
compression	O
was	O
described	O
as	O
mitigated	O
in	O
the	O
then-latest	O
versions	O
of	O
the	O
Chrome	B-Application
and	O
Firefox	B-Application
web	I-Application
browsers	I-Application
.	O
</s>
<s>
The	O
nginx	B-Operating_System
web-server	O
was	O
not	O
vulnerable	O
to	O
CRIME	O
since	O
1.0.9/1.1.6	O
(	O
October/November	O
2011	O
)	O
using	O
OpenSSL	B-Language
1.0.0	O
+	O
,	O
and	O
since	O
1.2.2/1.3.2	O
(	O
June	O
/	O
July	O
2012	O
)	O
using	O
all	O
versions	O
of	O
OpenSSL	B-Language
.	O
</s>
<s>
Note	O
that	O
as	O
of	O
December	O
2013	O
the	O
CRIME	O
exploit	O
against	O
HTTP	B-Protocol
compression	O
has	O
not	O
been	O
mitigated	O
at	O
all	O
.	O
</s>
<s>
Rizzo	O
and	O
Duong	O
have	O
warned	O
that	O
this	O
vulnerability	O
might	O
be	O
even	O
more	O
widespread	O
than	O
SPDY	B-Protocol
and	O
TLS	O
compression	O
combined	O
.	O
</s>
<s>
At	O
the	O
August	O
2013	O
Black	O
Hat	O
conference	O
,	O
researchers	O
Gluck	O
,	O
Harris	O
and	O
Prado	O
announced	O
a	O
variant	O
of	O
the	O
CRIME	O
exploit	O
against	O
HTTP	B-Protocol
compression	O
called	O
BREACH	B-Protocol
(	O
short	O
for	O
Browser	B-Protocol
Reconnaissance	I-Protocol
and	I-Protocol
Exfiltration	I-Protocol
via	I-Protocol
Adaptive	I-Protocol
Compression	I-Protocol
of	I-Protocol
Hypertext	I-Protocol
)	O
.	O
</s>
<s>
It	O
uncovers	O
HTTPS	B-Protocol
secrets	O
by	O
attacking	O
the	O
inbuilt	O
HTTP	B-Protocol
data	O
compression	O
used	O
by	O
webservers	O
to	O
reduce	O
network	O
traffic	O
.	O
</s>
