<s>
CCleaner	B-Application
(	O
,	O
originally	O
Crap	B-Application
Cleaner	I-Application
)	O
,	O
developed	O
by	O
Piriform	O
Software	O
,	O
is	O
a	O
utility	B-Application
used	O
to	O
clean	O
potentially	O
unwanted	O
files	O
and	O
invalid	O
Windows	B-Protocol
Registry	I-Protocol
entries	O
from	O
a	O
computer	O
.	O
</s>
<s>
It	O
was	O
originally	O
developed	O
for	O
Microsoft	B-Application
Windows	I-Application
only	O
,	O
but	O
in	O
2012	O
,	O
a	O
macOS	B-Application
version	O
was	O
released	O
.	O
</s>
<s>
An	O
Android	B-Application
version	O
was	O
released	O
in	O
2014	O
.	O
</s>
<s>
CCleaner	B-Application
can	O
delete	O
potentially	O
unwanted	O
files	O
left	O
by	O
certain	O
programs	O
,	O
including	O
Microsoft	B-Application
Edge	I-Application
,	O
Internet	B-Application
Explorer	I-Application
,	O
Firefox	B-Application
,	O
Google	B-Application
Chrome	I-Application
,	O
Opera	B-Application
,	O
Safari	B-Application
,	O
Windows	B-Device
Media	I-Device
Player	I-Device
,	O
eMule	B-Protocol
,	O
Google	B-Protocol
Toolbar	I-Protocol
,	O
Netscape	B-Protocol
,	O
Microsoft	B-Application
Office	I-Application
,	O
Nero	B-Application
,	O
Adobe	B-Application
Acrobat	I-Application
,	O
McAfee	O
,	O
Adobe	B-Operating_System
Flash	I-Operating_System
Player	I-Operating_System
,	O
Sun	B-Device
Java	I-Device
,	O
WinRAR	B-Application
,	O
WinAce	B-Application
,	O
WinZip	B-Application
and	O
GIMP	B-Application
along	O
with	O
browsing	O
history	O
,	O
cookies	B-Application
,	O
recycle	B-Application
bin	I-Application
,	O
memory	O
dumps	O
,	O
file	O
fragments	O
,	O
log	O
files	O
,	O
system	O
caches	B-General_Concept
,	O
application	O
data	O
,	O
autocomplete	O
form	O
history	O
,	O
and	O
various	O
other	O
data	O
.	O
</s>
<s>
The	O
program	O
includes	O
a	O
registry	B-Application
cleaner	I-Application
to	O
locate	O
and	O
correct	O
problems	O
in	O
the	O
Windows	B-Protocol
registry	I-Protocol
,	O
such	O
as	O
missing	O
references	O
to	O
shared	O
DLLs	O
,	O
unused	O
registration	O
entries	O
for	O
file	O
extensions	O
,	O
and	O
missing	O
references	O
to	O
application	B-Application
paths	I-Application
.	O
</s>
<s>
CCleaner	B-Application
2.27	O
and	O
later	O
can	O
wipe	O
the	O
MFT	O
free	O
space	O
of	O
a	O
drive	O
,	O
or	O
the	O
entire	O
drive	O
.	O
</s>
<s>
CCleaner	B-Application
can	O
uninstall	B-Application
programs	O
or	O
modify	O
the	O
list	O
of	O
programs	O
that	O
execute	O
on	O
startup	O
.	O
</s>
<s>
Since	O
version	O
2.19	O
,	O
CCleaner	B-Application
can	O
delete	O
Windows	O
System	O
Restore	O
points	O
.	O
</s>
<s>
CCleaner	B-Application
can	O
also	O
automatically	O
update	O
installed	O
programs	O
and	O
computer	O
drivers	O
.	O
</s>
<s>
CCleaner	B-Application
also	O
has	O
its	O
own	O
web	B-Application
browser	I-Application
called	O
CCleaner	B-Application
Browser	B-Application
.	O
</s>
<s>
CCleaner	B-Application
Browser	B-Application
is	O
included	O
to	O
optionally	O
install	O
in	O
the	O
CCleaner	B-Application
installer	O
,	O
but	O
it	O
can	O
also	O
be	O
installed	O
from	O
its	O
.	O
</s>
<s>
CCleaner	B-Application
Browser	B-Application
avoids	O
advertising	O
,	O
avoids	O
tracking	B-Application
,	O
has	O
built-in	O
security	O
against	O
all	O
kinds	O
of	O
malware	O
,	O
phishing	O
,	O
malicious	O
downloads	B-Application
,	O
and	O
also	O
avoids	O
unwanted	O
elements	O
such	O
as	O
pop-ups	O
or	O
excessive	O
browser	B-Application
cache	B-General_Concept
.	O
</s>
<s>
It	O
is	O
based	O
on	O
Google	O
's	O
free	B-License
and	I-License
open-source	I-License
project	O
Chromium	B-Language
.	O
</s>
<s>
The	O
browser	B-Application
is	O
only	O
available	O
for	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
CCleaner	B-Application
was	O
first	O
launched	O
in	O
2004	O
for	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
It	O
remained	O
a	O
Windows-only	O
utility	B-Application
until	O
2012	O
.	O
</s>
<s>
On	O
2	O
June	O
2011	O
,	O
Piriform	O
announced	O
a	O
public	O
beta	O
test	O
program	O
for	O
CCleaner	B-Application
for	O
Mac	B-Application
.	O
</s>
<s>
The	O
Mac	B-Application
version	O
graduated	O
to	O
the	O
test	O
stage	O
on	O
30	O
January	O
2012	O
.	O
</s>
<s>
Piriform	O
released	O
CCleaner	B-Application
for	O
Android	B-Application
in	O
2014	O
.	O
</s>
<s>
In	O
2016	O
Piriform	O
announced	O
2	O
billion	O
CCleaner	B-Application
downloads	B-Application
worldwide	O
.	O
</s>
<s>
In	O
January	O
2014	O
it	O
had	O
been	O
the	O
most	O
popular	O
software	O
on	O
FileHippo	B-Application
for	O
more	O
than	O
a	O
year	O
,	O
and	O
had	O
a	O
5-star	O
editor	O
's	O
rating	O
on	O
and	O
Softpedia	O
.	O
</s>
<s>
CCleaner	B-Application
has	O
been	O
reviewed	O
by	O
Chip.de,	O
TechRadar	O
,	O
PC	O
Magazine	O
and	O
TechRepublic	O
.	O
</s>
<s>
Upon	O
an	O
error	O
in	O
the	O
code	O
,	O
the	O
Active	O
Monitoring	O
component	O
of	O
CCleaner	B-Application
5.45	O
,	O
which	O
was	O
designed	O
to	O
measure	O
junk	O
levels	O
to	O
trigger	O
cleaning	O
,	O
switched	O
back	O
on	O
again	O
.	O
</s>
<s>
In	O
December	O
2018	O
,	O
it	O
was	O
reported	O
that	O
users	O
installing	O
CCleaner	B-Application
would	O
also	O
have	O
Avast	B-Operating_System
Antivirus	I-Operating_System
installed	O
without	O
their	O
permission	O
,	O
with	O
TechSpot	O
claiming	O
this	O
arguably	O
made	O
CCleaner	B-Application
no	O
better	O
than	O
the	O
malware	O
it	O
was	O
supposed	O
to	O
defend	O
against	O
.	O
</s>
<s>
In	O
July	O
2020	O
,	O
Microsoft	B-Application
Windows	I-Application
Defender	I-Application
began	O
flagging	O
the	O
free	O
version	O
of	O
CCleaner	B-Application
as	O
a	O
"	O
potentially	B-Application
unwanted	I-Application
application	I-Application
"	O
,	O
stating	O
that	O
"	O
while	O
the	O
bundled	O
applications	O
themselves	O
are	O
legitimate	O
,	O
bundling	O
of	O
software	O
,	O
especially	O
products	O
from	O
other	O
providers	O
,	O
can	O
result	O
in	O
unexpected	O
software	O
activity	O
that	O
can	O
negatively	O
impact	O
user	O
experiences.	O
"	O
</s>
<s>
After	O
Piriform	O
was	O
acquired	O
by	O
Avast	O
,	O
in	O
September	O
2017	O
,	O
CCleaner	B-Application
5.33	O
was	O
compromised	O
by	O
the	O
incorporation	O
into	O
the	O
distributed	O
program	O
of	O
the	O
Floxif	O
trojan	O
horse	O
that	O
could	O
install	O
a	O
backdoor	O
,	O
enabling	O
remote	O
access	O
to	O
2.27	O
million	O
machines	O
which	O
had	O
installed	O
CCleaner	B-Application
to	O
be	O
infected	O
.	O
</s>
<s>
Avast	O
insisted	O
that	O
the	O
malware	O
was	O
already	O
in	O
CCleaner	B-Application
version	O
5.33	O
,	O
prior	O
to	O
the	O
purchase	O
of	O
Piriform	O
.	O
</s>
<s>
On	O
13	O
September	O
,	O
Piriform	O
released	O
CCleaner	B-Application
5.34	O
and	O
CCleaner	B-Application
Cloud	O
1.07.3191	O
,	O
without	O
the	O
malicious	O
code	O
.	O
</s>
<s>
On	O
21	O
October	O
2019	O
,	O
Avast	O
disclosed	O
a	O
second	O
security	O
breach	O
during	O
which	O
attackers	O
tried	O
again	O
to	O
insert	O
malware	O
inside	O
CCleaner	B-Application
releases	O
.	O
</s>
