Iqembu abacwaningi baseGraz University of Technology e-Austria kanye ne-Helmholtz Center for Information Security (CISPA), bathole i-vector entsha yokuhlaselwa kweForeshadow (L1TF), ekuvumela ukuthi ukhiphe idatha kwimemori ye-Intel SGX enclaves, ama-SMM, izindawo zememori zohlelo lokusebenza lwe-kernel, nemishini ebonakalayo ezinhlelweni zokwenza okuhle.
Ngokungafani nokuhlaselwa kwasekuqaleni kweForeshadow, Ukuhluka okusha akucaciswanga kuma-processor we-Intel futhi kuthinta Ama-CPU avela kwabanye abenzi abanjengo I-ARM, IBM ne-AMD. Futhi, inketho entsha ayidingi ukusebenza okuphezulu futhi ukuhlaselwa kungenziwa ngisho nangokusebenzisa iJavaScript neWebAssembly kusiphequluli sewebhu.
IForeshadow isebenzisa iqiniso lokuthi lapho inkumbulo itholakala kukheli elibonakalayo, ekhiqiza okuhlukile (ukwehluleka kwekhasi lokugcina), iprosesa ibala ngekheli ngekheli futhi ilayishe idatha uma ikulondolozi lwe-L1.
Ukufinyelela kokuqagela kwenziwa ngaphambi kokuthi kuqedwe yetafula lekhasi lememori futhi ngaphandle kwesimo sokufakwa kwetafula lekhasi lememori (PTE), okungukuthi, ngaphambi kokuqinisekisa ukuthi idatha isememori ebonakalayo futhi iyafundeka.
Ngemuva kokuqeda isheke lokutholakala kwememori, lapho kungekho inkomba Yethula ku-PTE, ukusebenza kulahliwe, kepha imininingwane ibekiwe futhi ingatholwa kusetshenziswa izindlela zokunquma okuqukethwe okulondolozwe okwesikhashana ngokusebenzisa iziteshi eziseceleni (ngokuhlaziya ushintsho esikhathini sokufinyelela kudatha efakwe kunqolobane nengagciniwe).
Abaphenyi bakhombisile lokho izindlela ezikhona zokuzivikela kwiForeshadow azisebenzi futhi zenziwa ngokuchazwa okungalungile kwenkinga.
Ukuba sengozini kweForeshadow ingabanjiswa noma ngabe kusetshenziswa izindlela zokuvikela ku-kernel ezazibhekwa njengezanele phambilini.
Ngenxa yalokho, Abaphenyi bakhombise ukuthi kungenzeka ukwenza ukuhlaselwa kweForeshadow kumasistimu anezinhlamvu ezindala, lapho zonke izindlela zokuvikelwa zeForeshadow zinikwe amandla, kanye nezinhlamvu ezintsha, lapho kuvikeleka kuphela iSpecter-v2 (kusetshenziswa inketho ye-Linux kernel nospectre_v2).
Umphumela we-prefetch utholwe ukuthi awuhlobene nemiyalo ye-preetch yesoftware noma umphumela we-hardware prefetch ngesikhathi sokufinyelela kwememori, kepha kunalokho kuvela ekucabangeni kokucatshangelwa kwamarejista wesikhala somsebenzisi ku inhlamvu.
Lokhu kuchazwa ngokungeyikho kwembangela yokuba sengozini ekuqaleni kuholele ekucabangeni kokuthi ukuvuza kwedatha kuForeshadow kungenzeka kuphela ngesilondolozi se-L1, ngenkathi ubukhona bamazwibela ekhodi athile (amadivayisi we-prech) ku-kernel inganikela ekuvukeni kwedatha ngaphandle kwesilondolozi se-L1, ngokwesibonelo ku-L3 Cache.
Isici esidaluliwe sibuye sivule namathuba okwenza ukuhlaselwa okusha. kuhloswe ukuhumusha amakheli wangempela kumakheli wangempela ezindaweni ze-sandbox futhi kunqume amakheli nedatha egcinwe kumarejista we-CPU.
Njengamademo, kukhombisa abacwaningi ikhono lokusebenzisa umphumela oveziwe uku khipha idatha kusuka kunqubo eyodwa kuye kwenye ngokufaka cishe izingcezu eziyi-10 ngomzuzwana kusistimu ene-Intel Core i7-6500U CPU.
Ithuba lokuhlunga okuqukethwe kwamarekhodi liyakhonjiswa I-Intel SGX enclave (kuthathe imizuzu engu-15 ukuthola inani lama-32-bit elibhalwe kwirejista engama-64-bit).
Ukuvimba ukuhlaselwa kukaForeshadow nge-L3 cache, indlela yokuvikela iSpecter-BTB (Isigcini Sesibalo Samagatsha) ukusebenza kusethi ye-retpoline patch kuyasebenza.
Ngakho-ke, Abaphenyi bakholelwa ukuthi kubalulekile ukushiya i-retpoline inikwe amandla ngisho nasezinhlelweni ezinama-CPU amasha, asevele enokuvikela ekubekekeni engcupheni okwaziwayo ekusebenzeni okucatshangelwayo kwemiyalo ye-CPU.
Ngakolunye uhlangothi, Abamele i-Intel bathe abahlelile ukufaka ezinye izindlela zokuvikela ngokumelene neForeshadow kubaprosesa futhi bakuthathe njengokwanele ukunika amandla ukuvikelwa ekuhlaselweni yi-Specter V2 ne-L1TF (Foreshadow).
Umthombo: https://arxiv.org