Preventingmultiplayercheating

CMSC425.01Spring2019

Administrivia

• Finalhomework(Hw3)• Errata: Question2(a)hasabadheuristic.• Correctedhomeworkposted

• Finalmidterm• Prepmaterialonwebsite• Mondaywilldoreview• ThursdayMay8th

Today’squestion

Howtopreventcheating

Cheating…

• Frustratesplayers• Reducesingamepurchases• Causesplayerstoquit• Impactspaidplayerleagues

• Yourexperiences?

Considermoregenerally…

• Alwaysgoodtoconsidersecurity

• Howaregameslike

• Onlinebanking• Onlineretail• Socialmedia• Anythingnetworked

Cheating…

• Frustratesplayers• Reducesingamepurchases• Causesplayerstoquit• Impactspaidplayerleagues

• Yourexperiences?

• Howprevent?

Cheating…

• Frustratesplayers• Reducesingamepurchases• Causesplayerstoquit• Impactspaidplayerleagues

• Yourexperiences?

• Howprevent?

https://www.aimforest.com/cheat-detail/call-of-duty-ghosts-hacks-aimbots-and-other-cheats

PritchardonGamasutra

• Ifyoubuildit,theywillcometohackandcheat• Hackingattemptsincreaseasagamebecomesmoresuccessful• Cheatersactivelytrytocontrolknowledgeoftheircheats• Yourgame,alongwitheverythingonthecheater’scomputer,isnotsecure—notmemory,notfiles,notdevicesandnetworks• Obscurityisnotsecurity• Anycommunicationoveranopenlineissubjecttointerception,analysisandmodification• Thereisnosuchthingasaharmlesscheat• Trustintheserveriseverythinginclient-servergames• Honestplayerswouldlikethegametotipthemofftocheaters

Networkgamemodels

• Clientserver• Clientsoftware• Serversoftware

• Peertopeer• Identicalvs.differentclients• Withorwithoutlockstep

• Question• Howiscomputationshared?

https://developer.valvesoftware.com/wiki/Source_Multiplayer_Networking

Cheatingattacks• ReflexAugmentation:Improvephysicalperformance,suchasthefiringrateoraiming• InformationExposure:Clientsobtain/modifyinformationthatshouldbehidden.• Protocolcheats:Clientscaptureandmodifyordelaypackets• AuthoritativeClients:Althoughtheservershouldhavefullauthority,someonlinegamesgrantclientsauthorityovergameexecutionforthesakeofefficiency.Cheatersthenmodifytheclientsoftware.• Compromisedservers:Ahackedserverthatbiasesgame-playtowardsthegroupthatknowsofthehacks.• BugsandDesignLoopholes:Bugsanddesignflawsinthegameareexploited.InfrastructureWeaknesses:Differencesorproblemswiththeoperatingsystemornetworkenvironmentareexploited.

• https://en.wikipedia.org/wiki/Cheating_in_online_games

ReflexAugmentation

• Enhanceclientsoftware• Externallycapturepackets• Modifyclientcode

• Aimbot• Reflexenhancer• Howdetect?

ReflexAugmentation

• Enhanceclientsoftware• Externallycapturepackets• Modifyclientcode

• Aimbot• Reflexenhancer• Howdetect?• Checkclientexecutable• Analyzepackettraffic

InformationExposure

• Accessanduseinformationnotentitledto• Infrastructure-levelcheats

• Whatmightacheatuse?

InformationExposure

• Accessanduseinformationnotentitledto

• Whatmightacheatuse?• Keyvariables• Graphicshacks• Itemproperties• Physicsbehavior• Time(speedhack)• Ghosting

Keyvariables

• Lives,strength,health,etc.• Youhavetheexecutable– howfindthesevariables?

Keyvariables

• Lives,strength,health,etc.• Youhavetheexecutable– howfindthesevariables?

• Runprogram.• Ifnum_lives=5,searchforlocationswith5• Getkilled,findonethatjustdecreased

• Howprevent?

Keyvariables

• Lives,strength,health,etc.• Youhavetheexecutable– howfindthesevariables?

• Runprogram.• Ifnum_lives=5,searchforlocationswith5• Getkilled,findonethatjustdecreased

• Howprevent?• Encryptorprotectkeyvariables

Graphicshacks(removalofgameelements)

• Changelocalgraphicsrendering• Turnoffrenderingelements• Eliminatefog,walls,etc

Itemhacks

• Modifyitemproperties• Firingrate,accuracy,portionaction,itemfrequency

Physicsandspeedhacks

• Changecolliderbehavior• Changephysicsenginebehavior

• Controlgameclock

Ghosting

• Cooperationbetweentwoplayers• Onerunsasspectator• Informsactualplayeroflocationofotherplayers,etc

Protocolcheats

• Interferewithnetworkpackets• Packetsmaybeinserted,destroyed,duplicated,ormodified

• Suppressedupdate:• Acceptopponentpackets,suppressown,togetadvantage• Usesserverpolicyofinterpolatingandbackwinding• Preventbymonitoringpatternsofpacketdelay

Protocolcheats

• Interferewithnetworkpackets• Packetsmaybeinserted,destroyed,duplicated,ormodified

• Suppressedupdate:• Acceptopponentpackets,suppressown,togetadvantage• Usesserverpolicyofinterpolatingandbackwinding• Preventbymonitoringpatternsofpacketdelay

• Fixeddelay:• Delayallpackets• Localplayersseeinfofaster• Preventbylockstep,analysis,slidingpipelines

Protocolcheats

• Interferewithnetworkpackets• Packetsmaybeinserted,destroyed,duplicated,ormodified

• Inconsistency:corruptpackets• Time-stamp:postdatepackets• Spoofing:sentoutpacketsmasqueradingasotherplayer

DetectingCheating

• Signaturedetection- Detectingofcertainpatternsofbytesinmemory,checkedagainstadatabase(whitelist)• Heuristicanalysis- Statisticalanalysisofbehavior• Userreports- Informationprovidedbyotherusers

• 1.Metricsforbestpathonmap• 2.Navmesh process(R_D_Palgorithm,triangulation)

• 3.Walkableterrain• 4.Findpathsontriangulatedspace• 5.Configurationspaces• 6.Qualityofpath• 7.C-obstacles• 8.Minkowski sums• 9.Navmesh - grid,mulitresolution grid• 10.Visibilitygraph• 11.Medialaxis• 12.Randomizedplacement• 13.Rapidly-expandedRandomTrees(RRTs)• 14.L-systemplusturtle• 15.Fractaldimension

• 16.Randomizedand3DL-systems• 17.Particlesystems• 18.Flocking• 19.Mandelbrotsets• 20.Constructivesolidgeometry• 21.Shadingequation• 22.Bumpmapping• 23.Polygonalmeshes- basics,Euler'sformula

• 24.DECLdatastructures• 25.Perlinnoise• 26.A*• 27.Admissibleheuristic• 28.Multiplayercheatingattacks• 29.Forbiddenvelocitiesforcrowdmotion• 30.Fittingcubiccurvestodatapoints