<s>
An	O
XML	B-Application
denial-of-service	I-Application
attack	I-Application
(	O
XDoS	B-Application
attack	O
)	O
is	O
a	O
content-borne	O
denial-of-service	O
attack	O
whose	O
purpose	O
is	O
to	O
shut	O
down	O
a	O
web	O
service	O
or	O
system	O
running	O
that	O
service	O
.	O
</s>
<s>
A	O
common	O
XDoS	B-Application
attack	O
occurs	O
when	O
an	O
XML	B-Protocol
message	O
is	O
sent	O
with	O
a	O
multitude	O
of	O
digital	O
signatures	O
and	O
a	O
naive	O
parser	B-Language
would	O
look	O
at	O
each	O
signature	O
and	O
use	O
all	O
the	O
CPU	B-Device
cycles	O
,	O
eating	O
up	O
all	O
resources	O
.	O
</s>
<s>
These	O
are	O
less	O
common	O
than	O
inadvertent	O
XDoS	B-Application
attacks	O
which	O
occur	O
when	O
a	O
programming	O
error	O
by	O
a	O
trusted	O
customer	O
causes	O
a	O
handshake	O
to	O
go	O
into	O
an	O
infinite	B-Algorithm
loop	I-Algorithm
.	O
</s>
