Muva nje I-Intel iveze ukukhubazeka okusha okusha kuma-processor ayo, iphinde ibhekise kokuhlukile we-MDS owaziwayo (Microarchitectural Data Sampling) futhi kusekelwe ekusetshenzisweni kwezindlela zokuhlaziya ezivela eceleni kudatha ezakhiweni ze-microarchitecture. I- abacwaningi abavela eNyuvesi yaseMichigan naseVrije Universiteit Amsterdam (VUSec) bathole amathuba okuhlaselwa.
Ngokuya nge-Intel, lokhu kuthinta amaprosesa wamanje wedeskithophu kanye namaselula afana ne-Amber Lake, iKaby Lake, iCofi Lake, neWhisky Lake, kepha neCascade Lake yamaseva.
Isilondolozi
Owokuqala unegama elithi L1D Isampuli Yokuxoshwa noma i-L1DES ngamafuphi noma yaziwa nangokuthi yi-CacheOut, bhalisiwe njenge "CVE-2020-0549" lo nguye onobungozi obukhulu kakhulu selokhu ivumela ukucwila kwamabhuloki womugqa we-cache okuphoqelelwe ukuphuma kunqolobane yezinga lokuqala (L1D) kusikhala sokugcwalisa, okufanele singabi nalutho kulesi sigaba.
Ukunquma idatha esezingene kusibambisi se-padding, izindlela zokuhlaziya ezivela eceleni eziphakanyiswe phambilini ekuhlaselweni kwe-MDS ne-TAA (Transactional Asynchronous Abort) ziyasebenza.
Ingqikithi yokuvikelwa okwenziwe ngaphambilini kwe-MDS ne-TAA kuvele ukuthi, ngaphansi kwezimo ezithile, imininingwane ichithwa ngemuva kokuhlinzwa, ngakho-ke izindlela ze-MDS ne-TAA zisasebenza.
Njengomphumela, umhlaseli anganquma ukuthi ngabe idatha esusiwe kusuka kunqolobane yezinga eliphezulu ngesikhathi sokwenziwa kohlelo lokusebenza ngaphambili olwalunomgogodla we-CPU yamanje noma izinhlelo zokusebenza ezisebenza ngasikhathi sinye kweminye imicu enengqondo (i-hyperthread) kumgogodla ofanayo we-CPU (ukukhubaza i-HyperThreading kunganciphisi ukuhlaselwa).
Ngokungafani nokuhlaselwa kwe-L1TF, i-L1DES ayikuvumeli ukukhetha amakheli athile womzimba ukuqinisekisa, kepha ivumela ukuqapha kokungenzi lutho kokunye ukulandelana okunengqondo ehambisana nokulayisha noma ukugcina amanani kwimemori.
Ithimba le-VUSec liguqule indlela ye-RIDL yokuhlaselwa kwe-L1DES nokuthi uhlobo lokuxhaphaza luyatholakala, oludlula futhi indlela yokuvikela ye-MDS ehlongozwe yi-Intel, ngokususelwa ekusetshenzisweni komyalelo we-VERW ukusula okuqukethwe kwe-microarchitecture buffers lapho bebuya ku-kernel baye esikhaleni somsebenzisi noma lapho bedlulisa ukulawula ohlelweni lwezivakashi.
Ngaphezu kwalokho, futhi IZombieLoad ibuyekeze indlela yayo yokuhlasela ngobungozi be-L1DES.
Ngenkathi abacwaningi baseYunivesithi yaseMichigan bezenzele indlela yabo yokuhlasela I-CacheOut ekuvumela ukuthi ukhiphe imininingwane ebucayi ku-kernel yohlelo lokusebenza, imishini ebonakalayo kanye ne-SGX evikelekile. Le ndlela incike ekukhohlisweni ne-TAA ukunquma okuqukethwe kubhafa yokugcwalisa ngemuva kokuvuza kwedatha kusuka kunqolobane ye-L1D.
VRS
Ukuba sengozini kwesibili yi-Vector Register Sampling (VRS) okuhlukile kwe-RIDL (Rogue In-Flight Data Load), okuyi okuhlobene nokuvuza kwesitolo yemiphumela yerejista ye-vector funda imisebenzi eguqulwe ngesikhathi kwenziwa imiyalo ye-vector (SSE, AVX, AVX-512) kumgogodla ofanayo we-CPU.
Ukuvuza kwenzeka ezimeni ezithile ezingavamile futhi kubangelwa iqiniso lokuthi umsebenzi wokuqagela owenziwe, okuholela ekubonisweni kwesimo samarekhodi e-vector kusitoreji sesitoreji, uyabambezeleka futhi unqanyulwe ngemuva kokuthi i-buffer isuliwe, hhayi ngaphambili. Ngokufana nobungozi be-L1DES, okuqukethwe kubhafa yesitoreji kunganqunywa kusetshenziswa izindlela zokuhlasela ze-MDS ne-TAA.
Nokho, ngokusho kwe-Intel akunakwenzeka ukuthi kuxhashazwe njengoba ihlukaniswe njengeyinkimbinkimbi kakhulu ukwenza ukuhlaselwa kwangempela futhi wabela izinga eliphansi lobungozi, ngesilinganiso se-CVSS esingu-2.8.
Yize abaphenyi beqembu le-VUSec belungiselele uhlobo lokuxhaphaza olukuvumela ukuthi unqume amanani wamarejista e-vector atholwe ngenxa yezibalo kokunye ukulandelana okunengqondo komgogodla we-CPU ofanayo.
I-CacheOut ibaluleke kakhulu kuma-opharetha amafu, njengoba izinqubo zokuhlasela zingafunda idatha engaphezu komshini obonakalayo.
Okokugcina I-Intel ithembisa ukukhipha isibuyekezo se-firmware ngokuqalisa izindlela zokuvimba lezi zinkinga.