Measuring the Impact and Perception of Acceptable Advertisements

14 Pages·2015·1.9 MB·English

Measuring the Impact and Perception of
Acceptable Advertisements
Robert J. Walls Eric D. Kilmer Nathaniel Lageman Patrick D. McDaniel
DepartmentofComputerScienceandEngineering
PennsylvaniaStateUniversity,UniversityPark,PA,USA
{rjwalls,ekilmer,njl5114,mcdaniel}@cse.psu.edu
ABSTRACT strike a balance between the needs of users and publishers, and
theyemphasizetransparencyaskeytotheprogram’ssuccess[6,
In2011,AdblockPlus—themostwidely-usedadblockingsoftware—
22]. However, Eyeodrewstrongcriticismwhentheyconfirmed
begantopermitsomeadvertisementsaspartoftheirAcceptable
somecompanies—includingGoogle,Microsoft,andAmazon—paid
Adsprogram. Underthisprogram,someadnetworksandcontent
undisclosedamountstobeincludedinthewhitelist[9,32]. Some
providerspaytohavetheiradvertisementsshowntousers. Such
viewthisarrangementasaconflictofinterest;theorganizationthat
practiceshavebeencontroversialamongbothusersandpublishers.
providesblockingsoftwareisinapositiontoindirectlyprofitfrom
Inasteptowardsinformingthediscussionaboutthesepractices,
adsbeingshown.
we present the first comprehensive study of the Acceptable Ads
TheAcceptableAdsprogramimpactsmillionsofusersandbil-
program. Specifically,wecharacterizewhichadvertisementsare
lionsofdollars,1butlittleisknownaboutthewhitelistingprocess
allowedandhowthewhitelistinghaschangedsinceitsintroduction
orhowitimpactsusers.Inthispaper,weprovidethefirstcompre-
in2011.Weshowthatthelistoffiltersusedtowhitelistacceptable
hensivestudyoftheAcceptableAdsprogram.Weidentifyhowthe
advertisementshasbeenupdatedonaverageevery1.5daysandgrew
usersexperiencetheWebunderthisprogrambyexploringtheuse
from9filtersin2011toover5,900intheSpringof2015. More
ofadpolicies(calledfilterlists,orjustwhitelists).Wedeveloptools
broadly,thecurrentwhitelisttriggersfilterson59%ofthetop5,000
andtechniquestoexploreandcorrelateinformationfromInternet
websites. Ourmeasurementsalsoshowthattheprogramallows
measurements,acompletehistoryoftheprogram’swhitelist,instru-
advertisementson2.6millionparkeddomains.Lastly,wetakethe
mentedbrowserbehavior,andusersurveys.Inthis,wehavefocused
lessonslearnedfromouranalysisandsuggestwaystoimprovethe
onthefollowingquestions:
transparencyofthewhitelistingprocess.
1. Whatisinthewhitelistandhowhasitchangedovertime?
CategoriesandSubjectDescriptors
Wefindthatatthecurrentrevision,Rev. 988,thewhitelist
H.3.5[On-lineInformationServices]:Web-basedservices;K.4.4 contains5,936filtersandisupdatedevery1.5daystoaddor
[ComputersandSociety]:ElectronicCommerce modify11.4filtersonaverage.
2. Whobenefitsfromthewhitelist? Wefindthatthewhitelist
GeneralTerms identifies 3,545 unique explicitly listed publisher domains
(including15ofthetop100),andthatfivegeneral-purpose
AcceptableAds;AdblockPlus;AdAvoidance
filtertypesareresponsibleforallowingcontenton2,676,165
parkeddomains.
1. INTRODUCTION
3. Howdowemeasuretheimpactofthewhitelist?Wesurvey
Over144millionusersemployadblockingsoftware[27].Users whitelistuseintheAlexatop5,000mostpopularwebsites
aremotivatedbyadesiretohideintrusiveads,increasetheirprivacy, aswellas5,000sitesfromthe5kto1millionmostpopular.
orprotectthemselvesfrommaliciousadverts[34].Yet,someclaim Thecurrentwhitelisttriggersfilterson59%ofthetop5,000
adblockingthreatenstheWeb’sbusinessmodel.Indeed,Googlelost websitesbutexplicitlywhitelistonlyafewpercentofless
anestimated$887millioninrevenuetoblockinginQ22013[26,31]. popularsites.
In2011EyeoGmbH—themakerofthemostpopularadblocker,
4. Howdousersperceiveacceptableadvertisements?Asurvey
AdblockPlus—introducedtheirAcceptableAdsprogram.Through
ofover300usersshowedwidedissensiononmanyadver-
thisprogram,AdblockPlusallowssome“non-intrusive”adsthat
tisementsthatwerejudgedasbeinginvasive. Oneareaof
satisfyasetofcommunity-drivenguidelines,suchas“adsshould
agreementwasclear: advertisementsinterspersedwithand
neverobscurepagecontent.” AccordingtoEyeo,theirgoalisto
largelyindistinguishablefromwebcontentweredeemedas
Permissiontomakedigitalorhardcopiesofallorpartofthisworkforpersonalor undesirable.
classroomuseisgrantedwithoutfeeprovidedthatcopiesarenotmadeordistributed
forprofitorcommercialadvantageandthatcopiesbearthisnoticeandthefullcitation Our study is motivated by other large-scale Web and security
onthefirstpage. Copyrightsforcomponentsofthisworkownedbyothersthanthe
measurement studies, including those characterizing SPAM [14,
author(s)mustbehonored.Abstractingwithcreditispermitted.Tocopyotherwise,or
17], affiliate programs [20], domain abuse [4,7], and malicious
republish,topostonserversortoredistributetolists,requirespriorspecificpermission
and/[email protected]. advertising[19,34].WebeginbydetailingtheoperationofAdblock
IMC’15,October28–30,2015,Tokyo,Japan.
1TheInternetAdvertisingBureaureportedarecordhighof$12.4bil-
Copyrightisheldbytheowner/author(s).PublicationrightslicensedtoACM.
lioninU.S.advertisingrevenueforQ32014,breakingtheprevious
ACM978-1-4503-3848-6/15/10...$15.00.
recordof$12.1billioninQ4of2013[13].
DOI:http://dx.doi.org/10.1145/2815675.2815703.
107
<iframe id="ad_main" frameborder="0" scrolling="no" name="ad_main" src="http://static.adzerk.
net/reddit/ads.html?sr=-reddit.com,loggedout&amp;bust2#http://www.reddit.com"></iframe>
Figure1:SampleadcodefromReddit.ThiscodedisplaysaniframeforanAdzerkadvertisementontherightsideofthepage.Similarcodeconstructions
arecommonacrossdifferentsitesusingthesameadnetwork.ThisallowsAdblockPlustouseasinglefiltertoblockadsonmultipledomains.
PlusandtheAcceptableAdsprogram. Wethencharacterizehow
theprogramworksinpractice. Finally,weoffersuggestionsfor
improvingthetransparencyofthewhitelistingprocess.
2. ADBLOCKPLUS
AdblockPlusisthemostwidelyusedbrowserextensionwithover
50millionusersacrossallmajorbrowsers.2 In2014,theextension’s
Firefoxversionwasdownloaded68milliontimesandboasted19.2
millionusersdaily.3 AdblockPlusisopensourceandavailablefree
ofcharge.
Adblock Plus was created by Michael McDonald’s as a fork
of Henrik Aasted Sørensen’s Adblock project. In January 2006,
Wladimir Palant rewrote the code and released it as a separate
Figure2: AcceptableadsonReddit.com. Redditisamemberofthe
projectforFirefox. Sincethen,AdblockPlushasbeenportedto
AcceptableAdsprogram.Consequently,AdblockPlusallowsbothoftheads
run on all major browsers: Chrome (Dec. 2010 [28], formerly onthispage.Athird-partynetwork,Adzerk,servestheadontherightside
AdThwart[3]),Opera(Nov. 2012[10]),InternetExplorer(Aug. (labeled1). Thesponsoredlink(labeled2)isembeddeddirectlyintothe
2013[29]),andSafari(Jan. 2014[25]). EyeooffersanAndroid page.
version,butitisnotavailableintheGooglePlaystore[30].
AdblockPlususestextuallyencodedfilterstodeterminethecon-
tentshownonapage.Blockingfiltersrestrictpagecontent,while networks make it possible for publishers to show ads by simply
exceptionfiltersoverrideanymatchingblockingfilterstoallowthe includingasmallsnippetofcodeprovidedbytheadnetwork.This
content. Filterdefinitionsgenerallyconsistof: (i)amatchingex- straightforward interface also simplifies the blocking process by
pressionthatspecifieswhatcontenttoblock(orallow),e.g.,the allowingasinglefiltertoblockadsonmultiplesites.
URLofanadvertisingnetwork;and(ii)asetoffilteroptions,e.g., For example, reddit.com uses the code in Figure 1 to show
theimageoptionappliesthefiltertoimagerequests. Adetailed Adzerkadvertisements.WhenanAdblockPlususervisitsthepage,
descriptionofthefiltersyntaxisincludedinAppendixA. theirbrowserwillmakeathird-partywebrequesttofetchtheadver-
AdblockPlususersrarelywritetheirownfilters. Instead,they tisementfromAdzerk. AdblockPluswillpreemptthisrequestto
subscribetoregularlypublishedtext-basedfilterlists. Bydefault, checkiftherequestURLmatchesanyfilters.Ifthematchisfora
AdblockPlussubscribesuserstotwofilterlists:thefirst,EasyList, blockingfilter,suchasthefollowing,AdblockPluswillcancelthe
containstensofthousandsoffilterstoblockadvertisementsand request,stoppingthebrowserfromfetchingthead.
coversmostcommonadnetworks.Otherblockingextensionsalso 1 ||adzerk.net^$third-party
useEasyList,includingthesecondmostpopularblocker,AdBlock.
Theseconddefaultfilterlist—whichwerefertoastheAcceptable Inshort,theabovefilterwillblockallthird-partyrequeststoadzerk.
Adswhitelist—isusedtoimplementtheAcceptableAdsprogram. netoranyofitssubdomains.Foramorecompleteexplanationof
Inshort,thislistoverridestheuser’sotherfilterlistsallowingcertain filtersyntaxseeAppendixA.
publisherstoshowadvertisments. Wecharacterizethescopeand Iftherequestmatchesanexceptionfilter,5thenAdblockPlusal-
impactofthewhitelistinlatersections. lowsit,regardlessofanyblockingfiltermatches.Theadvertisement
Userscansubscribetoadditionalfilterliststhatprovidefunction- isthenshownasanimageontherightofthepage—denotedbythe
alitybeyondblockingadvertisementsincluding:disablingtracking, bold1inFigure2.
allowingtheuserto“browsethewebtrulyanonymously”,blocking
2.1.2 MatchingPageElements
knownmaliciousdomains,andremovingsocialmediabuttons,such
astheFacebookLikebutton.4 Wedeferanalysisoftheseliststo AdblockPlususesdifferentfiltersyntaxformatchingadvertising
futurework. elementsembeddeddirectlyintothepage.Similartohowrequest
filtersmatchURLs,elementfiltersuseCSSSelectors6toidentify
2.1 FilterMatching elementsbasedonattributessuchastheelement’sclassorid.
Broadly,individualfiltersmatchoneoftwotypesofcontent:Web The following filter blocks the “sponsored link” at the top of
requestsorpageelements.Webrieflydescribeeachbelow. Reddit’sfrontpage(bold2inFigure2)bymatchingelementswith
anidattributeofsiteTable_organic.
2.1.1 MatchingWebRequests
1 reddit.com###siteTable_organic
Publishersoftenrelyonthird-partyadnetworks,suchasAdzerk
orGoogleAdsense,todisplayadvertisementsontheirsite.These However,AdblockPlusdoesnotblockeitheroftheadvertise-
mentsinourexample.ItallowstheseadsbecauseRedditisapart
2https://adblockplus.org/en/about oftheAcceptableAdsprogram.
3https://addons.mozilla.org/en-US/firefox/addon/
adblock-plus/statistics/ 5Requestexceptionfiltersaredenotedbythe@@prefix.
4https://adblockplus.org/en/features 6http://www.w3.org/TR/CSS21/selector.html
108
Filter Restricted Blocking Unrestricted Sitekey
Category
6000 Added Added Unrestricted
About.com AdSense for Search
●
Added Google
Whitelist Released Search ads
ers4000 in ABP 2.0 Added Conversion
Filt Added Sedo Tracking for ●
of Sitekey DoubleClick
er
b Added
m
u2000 Reddit ●
N
●●
0 ●●
−01 −07 −01 −07 −01 −07 −01
2012 2012 2013 2013 2014 2014 2015
Figure3:ThegrowthoftheAcceptableAdswhitelist.Thewhitelisthasgrownsteadilysinceitsintroductionin2011.Onaverage,thisfilterlistisupdated
every1.5days,addingormodifying11.4exceptionfilters.Themostrecentversion(Rev.988onApril28,2015)includes5,936filters.Amongtheseareexceptions
fordomainparkingservices,conversionstracking,andthird-partyadnetworks.
3. ACCEPTABLEADS Eyeo’spracticeshaveincensedsomepublisherstosuchadegree
InMay2011,AdblockPlus’screator,WladimirPalant,outlined thattheyhaveaccusedthecompanyof“extortion”and“shaking
the criteria for Acceptable Ads with the goal of “encourag[ing] down”websites[23]. Recently,thiscriticismhasescalatedtothe
websitestouseadvertisingthatusersdon’tperceiveasannoying.”7 courtroom,andEyeoisfacinglawsuitsinFranceandGermany[11,
Theseguidelineshavebeenrefinedmultipletimesbasedonfeedback 12,16]. In Germany, publishers filed suit against Eyeo claiming
fromthecommunity. Whitelistedsitesarerequiredtoadhereto thattheirproductisanti-competitiveandthreatenstheirabilityto
theseguidelines. Toparaphrasethemostrecentcriteria[1],sites generaterevenue.TheregionalcourtinHamburgruledinfavorof
mustensurethat: Eyeoafterafourmonthtrial[15,33].
1. Advertisementscannotcontainanimations,sounds,or“attention- 3.1 FilterListMaintenance
grabbing”images.
Eyeoregularlyupdatesthewhitelist. Onaverage,thecompany
2. Advertisementscannotobscurepagecontentorobstructread-
addsormodifies11.4filtersevery1.5days,andhasadocumented
ingflow,i.e.,theadcannotbeplacedinthemiddleofablock
processforrequestingnewwhitelistfilterstobeadded.Theprocess
oftext.
ofaddingnewsitestotheAcceptableAdsprogramcomprisesfour
3. Advertisementsmustbeclearlydistinguishedfromthepage
steps:contact,application,agreement,andinclusion.
contentandmustbelabeledusingtheword“advertisement”
Thefirststep,contact,consistsofcommunicationbetweenEyeo
orequivalentterms.
andaperspectivepublisher.Eitherpartymayinitiatethisdialog[24].
4. Banner advertisements should not force the user to scroll
Next, Eyeoworkswiththepublishertoensuretheirsitefollows
downtoviewpagecontent.
theAcceptableAdsguidelines(theapplicationstep). OnceEyeo
confirmsthesite’sadvertisementsadheretotheirpolicy,theyestab-
AfterpublishingtheinitialAcceptableAdsrequirements,Palant
lishaprivateagreementwiththepublisher.Theseagreementsmay
andhispartner, TillFaida, createdEyeoGmbHinAugust2011.
involveafee,butEyeodoesnotcurrentlydisclosethefeestructure,
TheirgoalwastomaketheAdblockPlusproject“moresustain-
monetaryvalue,orlistofpayingpublishers. However,anecdotal
able”[8].Thefollowingmonth,thecompanybegansurveyingusers
abouttheirwillingnesstoallowadvertisinginsomeform.8 Bythe sourcesclaimthecompanyhasrequestedupto30%ofrecovered
revenue[5],andEyeoacknowledgestheyhaveexperimentedwith
year’sendreleasedAcceptableAdsasanopt-outfeatureinAdblock
Plusversion2.0.9 bothflatandperformance-basedfees[24].Afterreachinganagree-
ment,AdblockPlusaddsthefiltertothelistandsolicitscommunity
Theprogramhasbeencontroversial.Eyeodrewcriticismfrom
feedbackontheapplicationviaanonlineforum.10 Forumposts
bothusersandpublisherswhentheyconfirmedthatsomecompanies—
madeafterNov. 2014includelinkstothewhitelistrevisionand
includingGoogle,Microsoft,andAmazon—paidundisclosedamounts
optionalsamplescreenshots.
tobeincludedinthewhitelist[9,32].Eyeohasstatedthatreceived
funds are used to sustain the program. Further, they state that
whitelistingisfreeforsmallersitesandallparticipantsofthepro-
4. WHITELISTANALYSIS
grammustabidebytheacceptableadscriteria.
Inthefollowingsections,weexaminethecompletehistoryof
7https://adblockplus.org/forum/viewtopic.php?f=4&t=
Eyeo’sAcceptableAdsprogram.Ouranalysiscombineswhitelist
7551
8https://adblockplus.org/releases/ changeswithpublicdisclosuresandempiricalobservationsofbrowser
adblock-plus-1310-released behavior.Wefocusonansweringthefollowingbroadquestions.
9https://adblockplus.org/releases/
adblock-plus-20-released 10https://adblockplus.org/forum/viewforum.php?f=12
109
Year Revisions FiltersAdded FiltersRemoved DomainsAdded DomainsRemoved
2011 26 25 17 5 1
2012 47 225 30 59 4
2013 311 5152 1555 2248 73
2014 386 2179 775 859 125
2015 219 1227 495 371 207
Total 989 8808 2872 3542 410
Table1: YearlyactivityfortheAcceptableAdswhitelist. Thistableshowstheyear,numberofrevisions,numberoffirst-partydomains,andnumberof
changestoexceptionfilters—modificationsarecountedasnewfilters.ThedatacoverschangesuptoApr.28,2015(Rev.988).
1. Howhasthewhitelistchangedovertime? Weanalyzeall
Whitelist
revisionsofthewhitelisttoquantifythenumberofdomains Filters
andfilters.Section4.1.
2. Who benefits explicitly from the whitelist? We first char- e
p
acterizethewhitelistfiltersbasedontheirscopeandtarget o Restricted Sitekey Unrestricted
c
content.Then,weparsethewhitelistfilterstoextractexplic- S
itlylistedpublisherdomainsandgroupthesedomainsbased e
p Request Element Request Element
onpopularityandcategory.Section4.2. Ty
3. How do we measure the impact of the whitelist? We run
anautomatedsurveyacrossthetop5,000mostpopularweb- Figure4:HierarchyofFilterTypesintheWhitelist.
sitesand5,000additionalsitesfromthe5Kto1Mtopsites.
Section5.
4. Howdousersperceiveacceptableadvertisements?Wesurvey Figure 4 illustrates a hierarchy of whitelist filter types and their
305usersonAmazon’sMechanicalTurkplatformandask scope.Wediscusseachclassindetailbelow.
themtorate15“acceptable”advertisements.Section6
4.2.1 RestrictedExceptionFilters
4.1 WhitelistHistory Arestrictedexceptionfilterexplicitlydefinesthefirst-partydo-
Eyeo tracks all whitelist changes in a public Mercurial repos- mainsforwhichitactivates,i.e.,thefilterwillonlymatchwhenthe
itory.11 Using this repository, we extracted 988 versions of the userisbrowsingapageononeofthesedomains. Thesyntaxfor
whitelistdatingfromthestartofthewhitelistinOct.2011toApr. definingthedomainlistdependsonthefilter’stype.Forexample,
2015.Themostrecentversion(Rev.988)comprises5,936distinct the following are two of the whitelist’s restricted exceptions for
filters.Themajorityoftheseexceptionsallowadvertisementsand reddit.com.
otheradvertisingfunctionalitysuchasconversiontracking. 1 reddit.com#@##ad_main
Figure3showsthegrowthoftheAcceptableAdswhitelistover 2 @@||adzerk.net/reddit/$subdocument,
time. There are two large jumps visible in the figure. The first document,domain=reddit.com
correspondstoGoogle’sofficialadditiontothewhitelistonJune
21,2013(Rev.200).12 Intotal,thisrevisionadded1,262filtersfor Thefirstfilter—anelementexception—instructsAdblockPlusto
allowanyreddit.comelementswiththead_mainidentifier. For
Googlesearchadvertisementsongoogle.comandothervariations
elementfilters,restricteddomainsareprependedtothestart. The
ofthisURL,e.g., google.co.uk. Thesecondjumpwascaused
secondfilterallowsrequeststoadzerk.net, theadproviderfor
byfiltersforask.com,about.com,andrelatedsubdomains,e.g.,
reddit.com. In this case, the filter is restricted via the domain
cars.about.com.TheseadditionsarediscussedinSection7.
option.
Table1summarizestheyearlychanges.Thesecondfullyearof
Restricted exception filters make up 89% of the whitelist and
thewhitelist(2013)sawthelistgrowbyanorderofmagnitudeover
cover3,545fullyqualifieddomains,includingsearchengines(Mi-
thepreviousyear:Eyeomade4,633filterchanges,bringingthetotal
crosoft, Yahoo, Google), commercial sales (Walmart, Amazon),
to2,319publisherdomainscomparedtojust60domainsin2012.
contentpublishers(Reddit,About.com,Cracked),andISPs(Com-
However,aswediscussbelow,thesenumbersbelietheactualscope
cast,TimeWarner),amongstothers. Manyofthefullyqualified
ofthewhitelist.
domainsappearinginthewhitelistmaptothesamepublisher.Forin-
4.2 WhitelistScope stance,thewhitelistincludesover1,044subdomainsforabout.com,
including cars.about.com and food.about.com. Additionally,
InordertounderstandwhobenefitsfromtheAcceptableAds
thereare919country-baseddomainsforGooglepropertiesincluded
program,weneedtofirstunderstandthescopeofawhitelistfilter,
inthewhitelist,e.g.,google.co.ukandgoogle.de.Table2shows
i.e.,thesetofdomainsthatcanactivatethefilter.Forsomefilters,
therespectivecountandAlexarankingsforfullyqualifieddomains.
thislistofapplicabledomainsisexplicitlyenumeratedinthefilter’s
definition. We call these restricted filters. For others—namely 4.2.2 UnrestrictedExceptionFilters
unrestrictedandsitekeyfilters—thefiltercanapplytoanydomain.
Anunrestrictedexceptionfilterappliestoallfirst-partydomains,
Theimplicationhereisthatitisimpossibletodeterminetheactual
i.e., these exceptions can match on any site. The whitelist uses
impactofthesefiltersusingfilterdefinitionsalone.Instead,wecan
unrestricted exceptions primarily for two purposes. First, many
onlyempiricallyestimatethisvaluethroughsitesurveys(Section5).
of these filters enable conversion tracking. Broadly, conversion
11https://hg.adblockplus.org/exceptionrules trackingisusedtomeasureifanadvertisementresultedinsome
12https://hg.adblockplus.org/exceptionrules/rev/ useraction,e.g.,userpurchasedtheproductafterclickingonthead.
8bdf815a5291 Second,unrestrictedfiltersareusedtowhitelistspecificadnetworks.
110
Alexa FullyQualified Company Whitelisted Domains(.com)
Partition Domains Sedo 2011-11-30 1,060,129
All 1,990 ParkingCrew 2013-05-27 368,703
Top1,000,000 1,286 (0.12%) RookMedia 2013-07-31 949
Top5,000 316 (6.32%) Uniregistry 2013-09-25 1,246,359
Top1,000 167(16.70%) Digimedia 2014-07-02 25
Top500 112(22.40%) 2,676,165
Top100 33(33.00%)
Table3: Domainstatisticsforthefiveparkingserviceswhitelistedby
Table2: Domainsexplicitlyincludedinthewhitelist. Thewhitelistcon- AdblockPlus.RookMediawasremovedfromthewhitelistonSept.16,2014
tainsrestrictedexceptionfiltersfor3,544fullyqualifiedpublisherdomains. (rev.656);allothersremainactive.
Thiscorrespondsto1,990effectivesecond-leveldomains,e.g.,google.com
istheeffectivesecond-leveldomainofmaps.google.com.Percentagesare
onthetotalnumberofdomainswithintheparticularAlexapartition. Germany(thesamecityasEyeo). Thecompany’sfounder, Tim
Schumacher,isalsoEyeo’schiefinvestorandparticipatedinthe
initialdevelopmentoftheAcceptableAdsprogram[24].
Thispracticeallowstheadnetworktoshowadvertisementsacross
Currently,thereare4sitekeysand25sitekeyfiltersinthewhitelist,
multipledomainswithouthavingtoexplicitlyincludethesedomain
all belonging to domain parking services. They are, in order of
inthewhitelist.PageFairisanexampleofthelatter.
introduction,Sedo,ParkingCrew,Uniregistry,andDigimedia. A
PageFair. While PageFair is oft-quoted for their reports on the fifthsitekey(forRookMedia)wasremovedfromthewhitelistin
prevalenceofadblockinganditsmonetarycosts—infact,wecite Sept.2014.
oneintheintroduction—thecompanyisalsoanadnetworkinvolved Parkeddomainstypicallyexisttoshowadvertisements(andsell
intheAcceptableAdsprogram.13 domains),usuallyintheformoflinkstopagesrelatedtothedomain
name. Misspellings of popular sites are also frequently parked.
1 @@||pagefair.net^$third-party
Forexample,reddit.cmisaparkeddomainthatadvertisesdating
2 @@||tracking.admarketplace.net^$third-
servicesandphotosofcelebrities;thisdomainiswhitelistedunder
party
theAcceptableAdsprogramusingasitekey.Foramorecomplete
3 @@||imp.admarketplace.net^$third-party
treatment of domain parking, see the recent work by Alrwais et
TheseunrestrictedexceptionfiltersallowPageFairtoshowadver- al.[4].
tisementsonanypartneredwebsitewithoutneedingaseparateex- Using the top-level domain zone file for .com domains, we
ception for each domain. The company takes a “minority share identified approximately 3 million parked domains managed by
of the additional advertising revenue” that they provide publish- one of the parking services listed in Table 3. Specifically, we
ers.PageFairalsopaysEyeotoparticipateintheAcceptableAds focusedonthosedomainswhosenameserversbelongtooneof
program. thesitekeyparkingservices. Forexample,Sedodomainsusethe
Anotheradvertisingnetwork,Influads,hassimilarunrestricted ns1.sedoparking.comandns2.sedoparking.comnameservers.
exceptions. Thelistofparkingnameservers,inpart,wasderivedfromtheexam-
plesitesgiveninAdblockPlusonlineforums.Weusedautomated
1 @@||influads.com^$script,image
2 #@##influads_block toolstovisiteachsuspecteddomainandonlyrecordedthosethat
presentedasitekeysignature.
Thesecondofthesefilters—anelementexception—isnotactually Table3providesalowerboundonthenumberofdomainsfor
limitedtoInfluadsadvertisements;instead,thisfilterwillmatchany each parking service. In total, we find the four active sitekeys
elementonanysiteaslongastheelement’sidisinfluads_block. accountforatleast2,676,165distinctwhitelisteddomains.
This is the only example of an unrestricted element filter in the Finally,someoftheabovesitesrequiredspecialaccommodations
whitelist,andpossiblyanoversightbythewhitelist’sauthors. toscrape.Forexample,ParkingCrewdomainsemploycountermea-
InSection5,wefurtherexploretheimpactofthe156unrestricted surestopreventscraping,returninga403responseiftheuser-agent
exceptionfiltersusingasurveyofpopulardomains. stringmatchesthatofatoollikecurl.Further,somedomains,e.g.,
Uniregistry, behave differently given the presence or absence of
4.2.3 SitekeyExceptionFilters
specificcookievalues. Forinstance,whenauservisitsaUnireg-
AsitekeyexceptionfilterincludesaDER-encoded,base-64repre- istrydomainforthefirsttime,thesitewillreturnapagethatfirst
sentationofanRSApublickey. generatesacookieandthenredirectstheusertoanotherpagewith
1 ! Text ads on Sedo parking domains advertisements(andthesitekeysignature).
2 @@$sitekey=MFwwDQYJK...wEAAQ,document
Factoring Sitekeys. All current sitekeys use 512 bit RSA keys
AdblockPlusallowsadvertisementsonanydomainthatpresentsa (RSA-155). Such small key sizes are well within the factoring
validsignaturesignedwithacurrentsitekey. Effectively,sitekeys capabilities of an individual or publisher with modest hardware
delegatethetaskofwhitelistingtothepublisher. resources.Todemonstratethis,weconstructedaclustercomprising
AdblockPluscalculatesthesignaturebysigningastringcontain- 8desktopcomputersrunningUbuntu14.04,eachwithanIntelXeon
ingtheURI,hostname,anduser-agentstringoftheHTTPrequest. E5-2630clockedat2.30GHzand32GBofmemory.Weusedthe
AdblockPlusthencomparestheresultwiththesignaturereturnedby CADO-NFS14implementationoftheNumberFieldSievealgorithm.
theserverin:(i)theX-Adblock-keyheaderoftheHTTPresponse, Thissetuptookapproximatelyoneweekonaveragetofactoreach
and(ii)thedata-adblockkeyattributeofthereturnedpage. sitekey.
Thefirstsitekey—addedtothewhitelistbeforeitsrelease—belongs InFigure5,wedemonstratehowanadversarialpublishercould
toSedo,adomainparkingandhostingcompanybasedinCologne, useafactoredsitekeytoshowintrusiveormaliciousadvertising.
13https://pagefair.com/about/ 14http://cado-nfs.gforge.inria.fr/
111
(a)Withoutsitekey. (b)Withsitekey.
Figure5:Exploitingsitekeys.Usingaclusterofdesktopcomputers,wewereabletofactoroneofthewhitelistsitekeysinfivedays.Thederivedkeyallowed
ourtestsitetobypassAdblockPlus’sblockingentirely.
Forourproofofconcept,weusedAdblockPlus’sdefaultsettings matchesbytheheightandcolorofthebars,respectively.Domains
withboththeEasyListblacklistandtheAcceptableAdswhitelist explicitly included in the whitelist are shown in bold along the
enabled.Thefigureshowsourtestsitebeforeandafteraddingthe x-axis.
sitekey.Inshort,ourtestsitebypassedallblockingfilters. Thisfigureillustratesanumberofsubtleissueswhenmeasur-
ing filter behavior. First, 12 domains not explicitly included in
5. MEASURINGFILTERBEHAVIOR thewhitelistneverthelessactivatewhitelistfilters,e.g.,youtube.
com.Second,whitelistfiltersactivateneedlessly.Thatis,thefilter
Ourpreviousanalysis—focusingonthecontentofthewhitelist—
matchescontentthatwouldnothaveotherwisebeenblockedbythe
providesanecessarybutincompletepictureofthewhitelist’sbe-
EasyListblacklist. Third, sitesmaybehavedifferentlybasedon
havior. Forinstance,thewhitelistincludesanexceptionfilterfor
browserstateandconfiguration.Forexample,ask.comwillactivate
PageFairadvertisements,butitdoesnotlistanyofthedomainsthat
morefiltersiftheuserdoesnothavespecificcookiesinthebrowser
usePageFair.
cache.Further,somesiteswillshowdifferentadvertisementsifthe
Complicatingmatters,whitelistbehavioralsodependsonamyr-
sitesdetectsthepresenceofAdblockPlus,e.g.,imgur.com.
iadofmoresubtlefactorsincludingfilterambiguity,unpredictable
Finally,notallwhitelistfiltersaredirectlyresponsiblefordis-
websitebehavior,andcomplexinteractionsbetweendifferentfilters
playingadvertisements,e.g.,gstaticexceptions.Manycommon
andfilterlists.InthisSection,weexpandonourpreviousanalysis
exceptionsareforconversiontrackinganddonotvisuallyimpact
usingempiricalmeasurementsoffilteractivation.
thewebsite.
Theseresultssuggeststheneedformorecomplexanalysistech-
Methodology.WeinstrumentAdblockPlustomeasurefilteractiva-
niquestofullycharacterizethewhitelist’sbehavior.Weleavesuch
tionsondomainsdrawnfromfoursamplegroups:(i)the5,000most
populardomains,15(ii)1,000domainsrandomlysampledfromthe explorationsforfuturework.
rank5K–50Kpopularitystrata,(iii)1,000domainsrandomlysam-
pledfromtherank50K–100Kpopularitystrata,(iv)1,000domains 5.1 ActiveFiltersontheTop5KDomains
randomlysampledfromtherank100K–1Mpopularitystrata.
OftheTop5,000domains,3,956activatedatleastoneAdblock
WeinstrumentedAdblockPlustorecordfilteractivationsand
usedSelenium16tovisiteachdomain.Wesurveyedonlythelanding PlusfilterfromeithertheEasyListblacklistortheAcceptableAds
whitelist.Theremaining1,044domainswerelargelynon-English
pageofeachsite.Bylimitingourvisittothefirstpage,oursurvey
(andthusoutofthepurviewofEasylist)orrequiredadditionaluser
producesalowerboundonthenumberofmatchingfiltersassome
interactiontotriggerfilters,e.g.,logins,searchqueries,etc.
filterswillnotactivatewithoutuserinteraction.Forinstance,Google
Figure7showsthedistributionofthetotalanddistinctwhitelist
searchadsonlyappearafterasearch.
filtermatchespersurveyedsite.Weincludeonlydomainswithat
Figure6showsthefilteractivationsonthetop50siteswithat
leastonewhitelistfilteractivation(2,934sites). Toyota.comsaw
leastonefilteractivation. Weshowthenumberandtypeoffilter
themostfilteractivationswith83totalmatchesfor8distinctfilters,
15WebsitepopularitywasbasedonAlexarankingsfromApr.2015. 5%ofthesurveyedsitesactivatedatleast12exceptionfilters(non-
http://www.alexa.com/topsites distinct),and,onaverage,eachsiteactivated2.6distinctwhitelist
16http://www.seleniumhq.org/ filters.
112
filter_survey
Filter Whitelist EasyList EasyList−Overlapping
Source
20
n Filters11055 Whitelist Whitelist
o
pti 0
e
xc 0
Number of E2100 Sans Whitelist Sans Whitelist
googyloe.utcuobyme a.−ch aoo1mom. a−cz oow3inmk. i−cp oe4ditm a−w.i totr6egr .−cg qoo7q.om cg−lo e.m9 c−lol ii.i1nvn0ke .e−c doi1nm1. w−ce io1bym2o .a−ch oo1om4. e−cb og.aj1oyp5. o−cbgl loo1e.m6g cs−o p.j1otp8. g−co oo1hgm9al o−e. 1d22e03 .−cg mo2osm3no .−gcal oe2m.m6ac z−o. ou2n.k7 c−go .oj2rop8 eg−ld e.d2iftr9. g−coa oso3kmg0. l−ce .o3cm2o s−wm oo.r3hbdr3u .p−rc eo3sm4s .−co on3clm5mi a−acilli k.er3axu6d ps−r. enx3sevt7si .−dc eo3opm8s .a−cy op3iam9l .m−c go4urm2. g−co moi4ocm3gr l−oe s.r4ofu4t .g−c mo4aim5l .−cg oo4om7 g−l fe.4cit82 .g−co oo4gm9l i−e. me5das1bd .−cc ao5sgam2ho .−omc gaol5zem3o a−nddi. sstpd5leaer4y .cv−ick coo5evm6se .r−fcl oo5gm7w .go−co ooo5glgm8l e−.e. cc6oa0 nm−.a vm6ex3rg .−tcoi ooa6gnm5l y−ea. .cc6on6 −m. h6gk7o .−c o6m8 − 69
Figure6:Filtermatcheswithandwithoutthewhitelistenabled.TheupperpanelshowsthefiltermatcheswhenboththewhitelistandEasyListareenabled,
thebottomshowsmatcheswhenjustEasyListisenabled.WelimitthisfiguretositesthatmatchatleastonefilterfromeitherthewhitelistorEasyList(andelide
sina.com.cnforeaseofpresentation).Eachbarislabeledwiththedomainandrank.Bolddenotesdomainsexplicitlyincludedinawhitelistfilterdefinition.The
heightofthebarrepresentsthenumberofmatchesandthefillspecifiesthefilter’ssource.Filtersthatmatchinbothconfigurationsareshowninblack.
Filter(Truncated) Domains Modified Purpose
1 @@||stats.g.doubleclick.net^$script,image 1,559 2013-02-21 Conversiontracking.
2 @@||googleadservices.com^$third-party 1,535 2013-06-21 Googlesearchads.
3 @@||gstatic.com^$third-party 1,282 2013-06-21 Googlesearchads.
4 @@||googleads.g.doubleclick.net/pagead/view... 929 2013-08-08 Experimental.
5 @@||google.*/ads/user-lists/$image,subdoc... 892 2013-05-31 Conversiontracking.
6 @@||googletagmanager.com/gtm.js 746 2013-08-08 Experimental.
7 @@||fls.doubleclick.net^$subdocument,image 300 2013-03-20 Conversiontracking.
8 @@||doubleclick.net/activity*$subdocument,i... 135 2013-08-08 Experimental.
9 @@||google.com/adsense/search/*.js$domain=~... 78 2015-01-22 GoogleAdsense(A-filter)
10 @@||google.*/ads/conversion 69 2014-11-28 Conversiontracking.
11 @@||p.skimresources.com/px.gif?ch=1&rn= 53 2013-11-07 Texttoaffiliatelinks.
12 ||p.skimresources.com/px.gif?ch=2&rn= 53 2013-11-07 Blocking,texttoaffiliatelinks.
13 @@||r.skimresources.com/api/?$script 48 2013-08-27 Texttoaffiliatelinks.
14 @@||s.skimresources.com/js/*.skimlinks.js^$... 48 2013-08-14 Texttoaffiliatelinks.
15 @@||t.skimresources.com/api/track.php?$script 47 2013-08-27 Texttoaffiliatelinks.
16 @@||pagefair.net^$third-party 31 2014-01-30 PageFairads.
17 #@##influads_block 30 2012-11-08 Influadsads.
18 ||viglink.com/images/pixel.gif?ch=2$third-party 25 2014-06-02 Blocking,texttoaffiliatelinks.
19 @@||doubleclick.net/json 22 2013-08-08 Experimental.
20 @@||google.com/gen_204 20 2013-08-08 Experimental.
Table4:Mostcommonwhitelistfiltersinthesurvey.Thistabledisplaysthe20mostcommonexceptionfiltersfromoursurveyofAlexa’stop5,000websites.
Number9onthislistwasaddedwithoutcommunityvetting;itallowsGoogle’sAdSenseforsearchonnearlyalldomains.
Table4showsthe20mostcommonwhitelistexceptionfiltersin other resources to sites to increase browsing performance. The
theTop5,000group.Asexpected,allofthesefiltersareunrestricted. necessityofthegstatic.comfilterisuncleartous,giventhatEa-
Aswediscussedpreviously,unrestrictedfilterscantriggeronany syListdoesnotcurrentlycontainanyfiltersthatwouldblockthe
site. observedgstatic.comrequests.
The most activated filter, @@||stats.g.doubleclick.net^ We observed one unrestricted element exception filter, #@##
$script,image,triggeredon1,559domains(31.2%). Thisfilter influads_block, which activated on 30 different domains. As
isusedtoallowsconversiontracking.Thesecond-mostpopularfil- discussedinSection4.2.2,thisfilterpreventstheblockingofcon-
ter, @@||googleadservices.com^$third-party, wasobserved tentcontainedwithinanyelementwithanidofinfluads_block.
on1,535domains,andallowsadvertisementsfromGoogle’sAd-
Sensenetwork. Thethird-mostpopularfilter,@@||gstatic.com 5.2 FilterActivationsAcrossCategories
^$third-party,occurredon1,282domains. Thisfilterdoesnot
appear to contribute to the visibility of advertisements. Instead, Figure 8 shows the number of filters triggered by domains in
theGoogle-ownedgstatic.comservesfonts,scripts,images,and each group. The top portion shows categorical filter activation
frequencieswhilethelowerportionshowsfilteractivationfrequency
113
FSioltuerrce ● Whitelist ● EasyList GPrroopuoprtion ● 0.2 ● 0.4 ● 0.6
SWpoorrltds ●●●●●●●● ●●●● ●●●● ●● ●● ●● ●● ●● ●● ● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ● ● ●● ●● ●● ● ● ●● ●● ●● ● ● ●● ● ● ●● ● ●● ●● ●● ● ●●
Society ●●●●●●●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
Shopping ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
Science ●●●● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
Regional ●●●●●●●●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
Kids_aRRneedcf_ereHTrNeaeoentemiwocneenss ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●● ●●●●● ●●●●● ●●●●●●●●●● ●●●● ●●● ●●●● ●●●● ●●● ●●●●● ●●●● ●●●●● ●●●●● ●●●● ●●●●● ●●●●● ●●●● ●● ●●●●● ●●●● ●●●●● ●●●●● ●● ●●● ●●●● ●● ●●● ●●●●● ●●● ●●●● ●●●● ●●● ● ●●● ●●● ●●● ●●● ●●● ●●●● ●●●●● Category
Health ●●●● ●●●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
Games ●●●● ●●●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
Computers ●●●●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
BusinAerstss ●●●●●●●●●●●●●●●● ●● ●● ●● ●● ●● ●● ● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●●●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ●● ● ●● ●● ● ●● ●● ● ● ●● ●● ●●
Adult ●●● ● ● ● ● ● ● ● ● ● ●
top5k ●●●●●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● P
tottopop1p50100mkk ●●●●●●●●●●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● ●●● opularity
@ @||@st@@a|t|[email protected]||sgt.gado@tiooc@ug.|l|bclegoea@ocdmlois^@gc|le$||krte|.gvhagiin@[email protected]−.|.lsg|..glep.gc.ead*oosr/otoyamyugndl^bdlse$i/ttec.ua.ca.lsigtiecromk−.na.l.i.ncsatogs.m.e/.r.scafo..#.m/#/gdpit|.vu|@.[/.ibapd@ad|a^|dng=ssx.."@esy.datiic@dv||o−:2mf/.l/gmgs.a.^pctdd$−otso.haium/rdbly−dt−|e"|s]c/plaisadcrrwtkf|#o.|ylb#lnic..renicat/t.od^.e.s|$om||.b|s^ccyaur$i.otgt.m.hoemiaroo^.zdg$lon−tenehpti−r^aard$t#−t/dy#shs|ipi|feyrtarcsrduatt−rueyrmnp.eemac[.pritocudyob^m|a^=m|"d$^ktrgs|$|.|htx|oirarhdoi.eddrg..nvl−.d.seeptoc_i^a.uar$|tnbt|dlyehsneti@r_ec^ilifxd$.@−tc.a|.|hkcpi..drancordteo−u|ty|b^|pmla|$^aedar|$~ct|[email protected]−@en.r|sr.|etpgtoig/r^as.iroa$tntnco|yte|higgtirl.rv^iucetd.$.bo−ti.c.hcopmiro^amrdn$/t−tpayrhpidorajsrde|te−|cyntbp.isaczer/ootsygmre^aar$p.t.h?.hifiircl||sde..s.=c.eaordv.imso^n|&p|$gt#−eefh#nisf.rxyeb.d@sca−.tinc@pv|.no|.e/.eg|mra|mo^_@deo$mastagod@lehs|iro|eruf.vkrid*be/e−er.e.a|1|pxn.dtpaecset1r/urto^7cbytn$rmotaml^anh−|ia$cv|.tt.ikeas..h.rci.nrsamicekdatoo−r,atn5pmamn^adarie$|stt|htyewhi/rids.rdavondade.li−[email protected]@y^|mos|/$^tp*m.$.|h$t.|is.rh~kpii.dsr−sudm.k−r/i.b.edwpmsoraworcetuwusy/rocdmueeerlisnc.vtceesor.yc/m/*opmx/..p..x.gi...
Figure8: Filtermatchespergroupranking. Eachrowrepresents1,000domainswithintherespectiveAlexarankinggroup. Foreachgroupweplotthe
frequencyeachfilteristriggeredbydomainsinthatgroup.
Wealsofindthat4ofthesefiltersweretriggeredmoreoftenby
thetop5,000websitesthanbyanyoftheothergroups.Thereisone
Total Distinct filterthatwasusedmostoftenbythegroupofdomainsconsisting
fromAlexarank100,000to1,000,000.Thisparticularfilterisused
1.00 forconversiontracking.
es0.75 6. USERPERCEPTION
Sit
of Underlying the Acceptable Ads program is the goal that both
n 0.50 publishersandusersfindthewhitelistedadstobeacceptable.There
o
cti havebeenmanystudiesofhowusersperceiveWebadvertisements
Fra0.25 (e.g.,[21]),andthedegreetowhichtheyintrudeontheuserexperi-
ence(e.g., [18]).Inthissection,webuildontheseeffortstosurvey
userperceptionofadvertisementsonpopularwebsitesbasedonthe
criteriastatedinEyeo’sAcceptableAdsguidelines[1]. Weused
0.00
Amazon’sMechanicalTurk[2]tosolicitparticipation,limitingour
1 10 100
Number of Exception Filters pooltoworkerswithatleast5,000approvedsubmissionsandat
least98%approvalrate. Eachofthe305respondentswerepaid
1$USandcompletedthe72questionsurveyinabout10minutes.
Figure7:ECDFoffiltermatchespersurveyeddomain.Weonlyinclude
50%oftheusersusedsomeformofadblockingsoftwarebefore,
domainswithatleastonematch.Asinglefiltermaymatchmultipleelements
(orrequests)onasingledomain;thesolidlinerepresentsthetotalnumberof with61%usingtheGoogleChromebrowser,28%usingFireFox,
matcheswhilethedashedlineisthenumberofuniquematchingfilters. 9%Safari,and1%eachforOperaandInternetExplorer.Theresults
ofthesurveyarediscussedbelowandshowninFigure9.
Theonlinesurveyshowedeightdifferentsites,eachcontaining
forthemostpopularsitestakenfromAlexa. Wechosethetop50 oneormoreadvertisementsallowedbyAdblockPlus. Theeight
mostfrequentlyactivatedfiltersandfoundthatthe5mostactivated sites were selected based on their popularity and diversity of ad
filtersoutofboththeEasyListandWhitelistwereallfiltersfrom placement. Specifically,wechooseasearchengine(Google),an
thewhitelist.ThesefiltersalsorelatedtoGoogle.Thisimpliesthat imagehostingservice(Imgur),anonlineretailer(Walmart),aWeb
thesefiltersmaybemorebroadthannecessary. service(IsItUp.com),anonlinegameforum(Utopia-game.com),a
Wefindthatthewhitelistfiltersareskewedmoretowardsshop- humorwebsite(Cracked.com),aviralcontentcurator(ViralNova),
pingwebsites,whichwecanattributetothefilter’spurpose. andauser-submittedcontentsite(Reddit).
114
S1: The advertisements are eye catching and grab my attention. S2: The advertisements are clearly distinguished from page content.
75 75
Google #1 Utopia #1 Viralnova Taboola #2 Google #1 Utopia #1 Viralnova Taboola #2
Google #2 Utopia #2 Viralnova Taboola #3 Google #2 Utopia #2 Viralnova Taboola #3
65 Google #3 Reddit #1 Walmart #1 65 Google #3 Reddit #1 Walmart #1
Imgur #1 Reddit #2 Cracked.com #1 Imgur #1 Reddit #2 Cracked.com #1
IsItUp.com #1 Viralnova Taboola #1 Cracked.com #2 IsItUp.com #1 Viralnova Taboola #1 Cracked.com #2
55 55
Percent of respondents 234555 Percent of respondents 234555
15 15
5 5
Strongly disagree Disagree Neutral Agree Strongly agree Strongly disagree Disagree Neutral Agree Strongly agree
(a)Attentiongrabbingadvertisements (b)Advertisementdistinguishedfromcontent
SearchEngineMarketingAdvertisements
S3: The advertisements on this page obscure page content or obstruct reading flow. Attention Distinguished Obscuring
75 µ 0.217 0.597 -0.260
Google #1 Utopia #1 Viralnova Taboola #2
Google #2 Utopia #2 Viralnova Taboola #3 VAR(X) 0.304 0.095 0.219
65 Google #3 Reddit #1 Walmart #1
Imgur #1 Reddit #2 Cracked.com #1
IsItUp.com #1 Viralnova Taboola #1 Cracked.com #2 BannerAdvertisements
55
Percent of respondents 234555 VARµµ(X) AAC-tt000tto..ee.102nnn514tttii25e7oonnntAdDDviiessttr-00ii0tnn..i.71ggs9e53uu3m51ii5sshheneeddts OObb-000ss..cc.106uu241rr523iinngg
15 VAR(X) 0.009 0.305 0.178
5
(d)Meanandvarianceofthesurveyresponses. Calculatedbyassigning
Strongly disagree Disagree Neutral Agree Strongly agree integervalues[-2,2]totheLikertscale,e.g.,stronglydisagreewasgiven-2.
(c)Advertisementobscuringcontent
Figure9:Userperceptionsurveyresults.
Foreachwhitelistedadvertisement,weaskedtheparticipantsto fromthecontent.HencetheallowancebyAdblockPlusseemsto
ratetheirlevelofagreementwithstatementsrelatingtoacceptability beinconflictwiththeprogram’sstatedpolicies.
onaLikertscale,e.g.,“StronglyDisagree,”“Disagree,”“Neutral,” Statement3:Theadvertisementsonthispageobscurepagecon-
“Agree,”or“StronglyAgree.”Eachstatementisadirecttranscription tentorobstructreadingflow. -Thislaststatementmeasuresthe
fromtheAdblockPluspolicy(withminoradjustmentsforclarity) degreetowhichusersfeeltheadsareintrusiveoncontentuse.While
andstatescharacteristicsthatmustormustnotbetrueforanad- themixedcontent/advertisinggridsseemtoinhibitsomecontent
vertisementtobe“acceptable”.Ideally,AdblockPlusshouldonly use,otheradstrategieswereviewedasmoreinvasive.Inparticular,
allowadvertisementsthatmeetthesecriteria. alittlemorethanathirdofusersviewedsidebaradvertisements
Statement1: Theadvertisementsareeyecatchingandgrabmy (e.g.,Reddit#1,notshown),firstsearchresults(Google#1),and
attention. -Thisfirststatementmeasuresthelevelofdistraction topbaradvertisements(Cracked.com#1)asinhibiting.
thattheadvertisementhasontheuser. Thereweretwotypesof
Summary. While theabove results areinstructive, onemust be
advertisementsthatmanyusersfoundtobeattentiongrabbingor
carefulnottoover-readthemeaningofonesurvey.Asummaryof
distracting. Figure10showstwoexamplesoftheadvertisements
thesurveyresultsinFigure9(d)showsthatthereisbroaddissension
deemed most attention getting, (10a, Google Ad #2, with 73%
amongst the participants about what was acceptable, confusing,
agreeingorstronglyagreeing)theimage-basedsalesadvertisements
orinhibiting. However, thisreenforcesourexperience; wehave
displayed with search results on engines and, (10b, Utopia Ad
observedthateachpersonviewsadvertisementsdifferently—often
#2,45%)theadvertisingbarnexttonavigationbuttonsonmany
vastlyso. Therefore,anysinglepolicyofwhitelistingisunlikely
websites.
to serve the needs of a large and diverse user community well.
Statement2:Theadvertisementsareclearlydistinguishedfrom Developingdeeperandlargerstudiesofuserdesiresisneededto
pagecontent.-Thisstatementisdesignedtomeasurehowwellthe developabetterunderstandingofuserpreferencesandultimatelya
usercandistinguishtheadvertisementsfrompagecontent. Illus- morepreciseandflexibleadvertisementblockingpolicy.
tratedinFigure10,themixedcontent/advertisinggridimagesused
incuratorwebsitessuchasViralNovaappearstointentionallyblur
thelinesbetweenadvertisementandcontent.Almost90%ofusers 7. UNDOCUMENTEDFILTERS
viewingallgrid-layoutadsstatedthattheywerenotdistinguished
Overthecourseofouranalysisoutlinedintheprevioussections,
wediscoveredseveralinstanceswherefilterswereaddedwithout
115
(a)GoogleAd#2 (b)UtopiaAd#2 (c)ViralNovaAd#1
Figure10:Surveyadvertisementexamples.
community vetting or public disclosure. For completeness, we !A6
discusstworepresentativeinstanceshere. @@||Ask.com^$elemhide
@@||us.ask.com^$elemhide
Google’sintroduction.Googlewasofficiallyaddedtothewhitelist
@@||uk.ask.com^$elemhide
onJune21,2013(Rev. 200).17 Priortothis,Eyeoallowedsome
publishers(butnotall)toshowGoogleAdSenseforsearchadson
!A29
theirownsearchpages.Ofparticularnoteamongtheseexceptions
@@||google.com/adsense/search/ads.
arethetwofiltersaddedforgolem.de(Rev.67,Dec.2012).18
js$domain=search.comcast.net
1 @@||google.com/ads/search/module/ads/*/ @@||google.com/ads/search/module/ads/*/
search.js$domain=suche.golem.de|www. search.js$script,domain=search.
google.com comcast.net
2 www.google.com#@##adBlock @@||google.com/afs/$script,subdocument,
document,domain=search.comcast.net
TheseexceptionfiltersarestructureddifferentlythanpreviousAd-
Sensefilters.Namely,thefirstexceptionspecifiesbothgolem.de !A46
and www.google.com in the domain list. This is unusual as the @@||kayak.com.au^$elemhide
additionofGoogleinthefirst-partydomainoptionisnotneces- @@||kayak.com.br^$elemhide
saryforshowingsearchadvertisementsongolem.de.Rather,this @@||checkfelix.com^$elemhide
option makes the filter active on www.google.com. The second
filter is even more unusual as it unblocks the adBlock element !A50
onwww.google.com, i.e., thefilterdoesnotmakeanyreference @@||twcc.com^$elemhide
togolem.de. NoneofthepreviousAdSenseexceptionsincluded @@||google.com/adsense/search/ads.
analogousfilters. js$domain=twcc.com
Roughlytwoweekslater,Eyeomodifiedthesefilters19tomatch @@||google.com/ads/search/module/ads/*/
otherrestrictedAdSenseexceptions. Inparticular,theyremoved search.js$script,domain=twcc.com
www.google.comfromthedomainlistinthefirstfilteranddeleted
thesecondfilterentirely.
Figure11: SubsetofA-filtergroups. Incontrasttotypicalfilters,A-filter
1 @@||google.com/ads/search/module/ads/*/ groupsdonotcontainacommentwithalinktotheforum.Insofaraswecan
search.js$domain=suche.golem.de determine,noneofthesefilterswerepubliclydisclosedbyEyeo.Intotal,we
uncovered59A-filtergroups.
Theforumpostforthegolem.defiltersdoesnotprovideanyra-
tionalefortheinitialdissimilaritiesbetweentheseotherAdSense
exceptions,nordoesitindicatethepurposeofthelaterchanges(or
evenmentionsuchchangesweremade).However,duringthetwo
A-Listfilters.Thereare61instancesofEyeoaddingwhitelistfilters
weekstheoriginalfilterswereactive, Googlecouldconceivably
withoutcommunityvetting—manyofwhichareexceptionsforlarge
haveusedthefilters(especiallytheelementfilter)tomeasurethe
companies.WerefertotheseasA-filtersbecauseofthenondescript
impactofwhitelistingbyaddinganelementwithidadBlock.This
commentsprecedingeachgroupinthewhitelist,e.g.!A1.Figure11
elementwouldbeactiveviathewhitelistwhennormaladswerenot.
shows four example sets. Insofar as we can determine, none of
17hg.adblockplus.org/exceptionrules/rev/8bdf815a5291 thesefilterswerepubliclydisclosed. Inotherwords,noneofthe
18hg.adblockplus.org/exceptionrules/rev/feb913d65a21 A-filtergroupsappearinEyeo’snotificationforum. NearlyallA-
19hg.adblockplus.org/exceptionrules/rev/9c5f8032d88b filteradditionsusethesamerepositorycommitmessage,“Updated
116