Iqela labaphandi ukusuka kwiDyunivesithi yasimahla yaseAmsterdam, iSwitzerland Higher Technical School yeZurich kunye neQualcomm uqhube isifundo malunga nokusebenza kokhuseleko ngokuchasene Uhlaselo Umqolo isetyenziswe kwii-chip memory ze-DDR4, ezivumela umxholo wezinto ezizimeleyo zememori yokufikelela ngokungacwangciswanga (i-DRAM) ukuba itshintshwe.
Iziphumo zazidanisa okoko i-DDR4 ihlala isengozini (CVE-2020 to 10.255) to RowHammer, as le bug ivumela ukugqwetha umxholo omncinci imemori nganye Ukufunda ngokujikeleza idatha kwiiseli ezikufutshane.
Kuba i-DRAM iludidi lwesibini lweeseli, nganye nganye ine-capacitor kunye ne-transistor, ukufundwa okuqhubekayo kwindawo enye yenkumbulo kukhokelela ekuguqulweni kwamandla ombane kunye neempazamo, kubangela ukwehla koxinzelelo oluncinci kwiiseli ezingabamelwane.
Ukuba ubungakanani bokufunda bukhulu ngokwaneleyo, emva koko iseli inokulahleka isixa esikhulu esaneleyo sentlawulo kwaye umjikelo wokuphinda uzalwe ngokutsha awuyi kuba nexesha lokubuyisela imeko yentsusa, eya kuthi ikhokelele kutshintsho kwixabiso ledatha egcinwe kwiseli .
Ukuthintela oku, iichips ze-DDR4 zanamhlanje zisebenzisa itekhnoloji ye-TRR. (Target Row Refresh), eyilelwe ukuthintela ukuphazamiseka kweseli ngexesha lokuhlaselwa kweRowHammer.
Ingxaki yile akukho ndlela imanyeneyo yokuphunyezwa kwe-TRR kwaye i-CPU nganye kunye nomenzi wememori uguqulela i-TRR ngendlela yabo, besebenzisa ezabo iindlela zokukhusela ngaphandle kokuveza iinkcukacha zokuphunyezwa.
Ukufunda ngeendlela ezisetyenziswa ngabavelisi ukuvimba iRowHammer yenze kwalula ukufumana iindlela zokujikeleza ukhuseleko.
Ngexesha lokuqinisekisa, kwavela ukuba "ukhuseleko ngokungabonakali" umgaqo osetyenziswe ngabavelisi ngexesha lokuphunyezwa kwe-TRR kunceda kuphela ukukhusela kwiimeko ezizodwa, ezibandakanya ukuhlaselwa okuqhelekileyo okuguqula utshintsho kumthwalo weseli kumqolo omnye okanye emibini emelene.
Ukusetyenziswa okuphuhliswe ngabaphandi kusivumela ukuba sivavanye ubukho beetshipsi kukhetho oluhlaselayo lweRowHammer, apho kwenziwa khona inzame yokuphembelela ukulayishwa kwemigca eliqela yeeseli zememori ngaxeshanye.
Olu hlaselo lunokudlula kukhuseleko lweTRR iphunyezwe ngabavelisi abathile kwaye ikhokelela kwimemori yokugqwetha kancinci nakwiikhompyuter ezintsha ezinememori ye-DDR4.
Kwii-DIMM ezingama-42 ezifundwayo, i-13 ibisesichengeni kukhetho oluqhelekileyo lokuhlaselwa kweRowHammer, ngaphandle kokukhuselwa. I-SK Hynix, iMicron kunye ne-Samsung yokumilisela iimodyuli ezinengxaki, iimveliso zazo zigubungela i-95% yentengiso yeDRAM.
Ukongeza kwi-DDR4, Iichipsi ze-LPDDR4 ezisetyenziswe kwizixhobo eziphathwayo nazo zafundwa, que babekwanobuzaza ukhetho oluphambili lweRowHammer. Ngokukodwa, imemori esetyenziswe kwiGoogle Pixel, Google Pixel 3, LG G7, OnePlus 7 kunye ne-Samsung Galaxy S10 ii-smartphones zachaphazeleka.
Abaphandi babenakho ukuvelisa ngeendlela ezahlukeneyo zokuxhaphaza kwiitshipsi ze-DDR4 enzima.
Ukusetyenziswa kweRowHammer yokuxhaphaza i-PTE (ukungena kwetafile yamaphepha) kuyadingeka ukufumana ilungelo lokuhlaselwa kwe-kernel ngaphakathi kwemizuzwana eyi-2.3 ukuya kwiiyure ezintathu kunye nemizuzwana elishumi elinesihlanu, kuxhomekeke kwitshiphusi ezivavanywayo.
Uhlaselo lomonakalo kwi-RSA-2048 yoluntu olugcinwe kwimemori luthathe kwimizuzwana engama-74.6 ukuya kwimizuzu engama-39 kunye nemizuzwana engama-28. Uhlaselo lokuphepha ugunyaziso ngokuguqula imemori yenkqubo yesudo yathatha imizuzu engama-54 kunye nemizuzwana eli-16.
Ukuvavanya iichips zememori ze-DDR4 isetyenziswe ngabasebenzisi, Umsebenzi weTRRespass ukhutshiwe. Uhlaselo oluyimpumelelo lufuna ulwazi malunga nokubekwa kweedilesi ezibonakalayo ezisetyenziswa kwisilawuli sememori ngokunxulumene neebhanki kunye nemiqolo yeeseli zememori.
Ukufumanisa ubeko, Ukusetyenziswa komdlalo kuphuculwe ngakumbi, okufuna ukuqala ngamalungelo engcambu. Kwixesha elizayo elikufutshane, kucwangcisiwe ukupapasha isicelo sokuvavanya inkumbulo yee-smartphones.
Iinkampani ze-Intel kunye ne-AMD zincomela ukukhusela ukusetyenziswa kwememori ngokulungiswa kwempazamo (ECC), abalawuli bememori ngenkxaso ye-MAC kwaye basebenzise inqanaba lokuhlaziya eliphezulu.
Umthombo: https://www.vusec.net