<s>
A	O
pingback	B-Application
is	O
one	O
of	O
four	O
types	O
of	O
linkback	B-Application
methods	O
for	O
Web	O
authors	O
to	O
request	O
notification	O
when	O
somebody	O
links	O
to	O
one	O
of	O
their	O
documents	O
.	O
</s>
<s>
Some	O
weblog	O
software	O
and	O
content	B-Protocol
management	I-Protocol
systems	I-Protocol
,	O
such	O
as	O
WordPress	B-Application
,	O
Movable	B-Protocol
Type	I-Protocol
,	O
Serendipity	B-Protocol
,	O
and	O
Telligent	B-Protocol
Community	I-Protocol
,	O
support	O
automatic	O
pingbacks	B-Application
where	O
all	O
the	O
links	O
in	O
a	O
published	O
article	O
can	O
be	O
pinged	O
when	O
the	O
article	O
is	O
published	O
.	O
</s>
<s>
Other	O
content	B-Protocol
management	I-Protocol
systems	I-Protocol
,	O
such	O
as	O
Drupal	B-Application
and	O
Joomla	B-Protocol
,	O
support	O
pingbacks	B-Application
through	O
the	O
use	O
of	O
addons	O
or	O
extensions	O
.	O
</s>
<s>
Essentially	O
,	O
a	O
pingback	B-Application
is	O
an	O
XML-RPC	B-Protocol
request	O
(	O
not	O
to	O
be	O
confused	O
with	O
an	O
ICMP	O
ping	B-Protocol
)	O
sent	O
from	O
Site	O
A	O
to	O
Site	O
B	O
,	O
when	O
an	O
author	O
of	O
the	O
blog	O
at	O
Site	O
A	O
writes	O
a	O
post	O
that	O
links	O
to	O
Site	O
B	O
.	O
</s>
<s>
The	O
request	O
includes	O
the	O
URI	B-Protocol
of	O
the	O
linking	O
page	O
.	O
</s>
<s>
If	O
that	O
link	O
exists	O
,	O
the	O
pingback	B-Application
is	O
recorded	O
successfully	O
.	O
</s>
<s>
This	O
makes	O
pingbacks	B-Application
less	O
prone	O
to	O
spam	O
than	O
trackbacks	B-Application
.	O
</s>
<s>
Pingback-enabled	O
resources	O
must	O
either	O
use	O
an	O
X-Pingback	O
header	B-General_Concept
or	O
contain	O
a	O
element	O
to	O
the	O
XML-RPC	B-Protocol
script	O
.	O
</s>
<s>
The	O
Pingback	B-Application
specification	O
was	O
developed	O
in	O
2002	O
by	O
Stuart	O
Langridge	O
,	O
Simon	O
Willison	O
,	O
and	O
Ian	O
Hickson	O
.	O
</s>
<s>
In	O
March	O
2014	O
,	O
Akamai	B-Application
published	O
a	O
report	O
about	O
a	O
widely	O
seen	O
exploit	O
involving	O
pingback	B-Application
that	O
targets	O
vulnerable	O
WordPress	B-Application
sites	O
.	O
</s>
<s>
Details	O
about	O
this	O
vulnerability	O
have	O
been	O
publicized	O
since	O
2012	O
,	O
with	O
Akismet	O
reporting	O
in	O
2013	O
that	O
"	O
almost	O
100%	O
of	O
trackbacks	B-Application
and	O
pingbacks	B-Application
are	O
spam	O
"	O
.	O
</s>
<s>
The	O
pingback	B-Application
attacks	O
consist	O
of	O
"	O
reflection	O
"	O
and	O
"	O
amplification	O
"	O
:	O
an	O
attacker	O
sends	O
a	O
pingback	B-Application
to	O
a	O
legitimate	O
Blog	O
A	O
,	O
but	O
providing	O
information	O
of	O
the	O
legitimate	O
Blog	O
B	O
(	O
impersonation	O
)	O
.	O
</s>
<s>
Then	O
,	O
Blog	O
A	O
needs	O
to	O
check	O
Blog	O
B	O
for	O
the	O
existence	O
of	O
the	O
informed	O
link	O
,	O
as	O
it	O
's	O
how	O
the	O
pingback	B-Application
protocol	O
works	O
,	O
and	O
thus	O
it	O
downloads	O
the	O
page	O
off	O
Blog	O
B	O
server	O
's	O
,	O
causing	O
a	O
reflection	O
.	O
</s>
<s>
This	O
can	O
lead	O
to	O
10x	O
,	O
20x	O
,	O
and	O
even	O
bigger	O
amplifications	O
(	O
DoS	B-Device
)	O
.	O
</s>
<s>
WordPress	B-Application
changed	O
a	O
bit	O
how	O
the	O
pingback	B-Application
feature	O
works	O
to	O
mitigate	O
this	O
kind	O
of	O
vulnerability	O
:	O
the	O
IP	O
address	O
that	O
originated	O
the	O
pingback	B-Application
(	O
the	O
attacker	O
address	O
)	O
started	O
being	O
recorded	O
,	O
and	O
thus	O
shown	O
in	O
the	O
log	O
.	O
</s>
<s>
Notwithstanding	O
,	O
in	O
2016	O
,	O
pingback	B-Application
attacks	O
continued	O
to	O
exist	O
,	O
supposedly	O
because	O
the	O
website	O
owners	O
do	O
n't	O
check	O
the	O
user	O
agent	O
logs	O
,	O
that	O
have	O
the	O
real	O
IP	O
addresses	O
.	O
</s>
<s>
Thus	O
,	O
it	O
's	O
still	O
recommended	O
to	O
disable	O
the	O
pingbacks	B-Application
,	O
to	O
prevent	O
attacking	O
other	O
sites	O
(	O
although	O
this	O
does	O
not	O
prevent	O
being	O
target	O
of	O
attacks	O
)	O
.	O
</s>
