I-Retbleed, ubuthathaka obutsha bohlobo lweSpecter oluchaphazela i-Intel kunye ne-AMD

Ulwazi lwakhutshwa malunga ne-a uhlaselo olutsha apho i-Intel kunye ne-AMD processors zisengozini, uhlaselo oluqikelelwayo lwamva nje lunokuvuza ngokufihlakeleyo amagama ayimfihlo kunye nezinye iinkcukacha ezinovakalelo.

phantsi kwegama lekhowudi "Retbleed", uhlaselo lujolise kwii-retpolines, enye yeendlela zokukhusela ezicetywayo kwi-2018 ukunciphisa i-Specter, i-subset ye-microarchitectural synchronization side-channel attack echaphazela ii-microprocessors zanamhlanje.

Bobabini abenzi beetshiphu baphinda bayasokola ukuqulatha into ejike ibe bubungozi obuzingileyo nobunenkani.

I-Retbleed bubuthathaka kutshanje ifunyenwe ngabaphandi kwi-Swiss Federal Institute of Technology (ETH) evela eZurich. Inegama layo kuba isebenzisa ukhuselo lwesoftware eyaziwa ngokuba yi-retpoline.

Olu khuselo lwaziswa ngo-2018 ukunciphisa iziphumo eziyingozi zohlaselo oluqikelelwayo lokubulawa. Uhlaselo oluqikelelwayo lusebenzisa into yokuba xa abaqhubekekisi bale mihla bedibana nesebe lomyalelo othe ngqo okanye ongathanga ngqo, baqikelela idilesi yomyalelo olandelayo abaza kuwufumana kwaye bawuphumeze ngokuzenzekelayo phambi kokuba uqikelelo luqinisekiswe.

Uhlaselo oluqikelelwayo lusebenza ngokuqhatha iprosesa ukwenza umyalelo ofikelela kwidata enovakalelo kwinkumbulo eqhele ukwaliwa kwisicelo esingathandekiyo. Idata iyabuyiswa emva kokurhoxisa umsebenzi.

I-retpoline isebenza ngokusebenzisa uthotho lwemisebenzi yokubuyisela ukwahlula amasebe angathanga ngqo ohlaselo oluqikelelwayo lokubulawa, ngokusebenzayo ukumisa isoftwe elingana nespringboard ezithi ziphume ngokukhuselekileyo. Ngamanye amazwi, i-retpoline isebenza ngokutshintsha imitsi kunye neefowuni ezingathanga ngqo kunye neembuyekezo.

Nangona kukho iinkxalabo, ingozi yokuziphatha kwangaphambili ukubuyiswa kwiimfumba zefowuni ezinzulu zazithathwa njengephantsi kwaye ii-retpolines zaba yeyona ndlela yokunciphisa i-Specter. Abanye abaphandi baye balumkisa iminyaka ukuba olu khuselo alwanelanga ukunciphisa uhlaselo oluqikelelwayo, njengoko bekholelwa ukuba imbuyekezo esetyenziswe yi-retpoline yayichaphazeleka kwi-BTI. Umyili weLinux uLinus Torvalds uzikhabile ezo zilumkiso, exoxa ukuba izinto ezinjalo azinakwenzeka.

Nangona kunjalo, abaphandi be-ETH Zurich bafumene ukuba imigodi, eneneni, ilungile. Abaphandi e-ETH Zurich babonise ngokucacileyo ukuba i-retpoline ayanelanga ukunqanda uhlaselo oluqikelelwayo lokubulawa. Ubungqina babo bengqiqo busebenza ngokuchasene neeprosesa ze-Intel ezine-Kaby Lake kunye ne-Coffee Lake microarchitectures kunye ne-AMD Zen 1, i-Zen 1+ kunye ne-Zen 2 microarchitectures.

"Iziphumo zethu zibonisa ukuba yonke imiyalelo ebuyayo elandela isitayile somnxeba esinzulu ngokwaneleyo inokugqithwa kusetyenziswa imbali yesebe echanekileyo kwi-Intel CPUs. Ngokumalunga nabaqhubekekisi be-AMD, sifumanisa ukuba nawuphi na umyalelo wokubuyiswa unokuqweqwediswa, kungakhathaliseki ukuba bekuphi na ukufowunelwa kwangaphambili, ukuba nje indawo ekufikelelwa kuyo isebe langaphambili ikhethwe ngokuchanekileyo ngexesha lokuqweqwediswa,” kuphawulwe abaphengululi e-L. ETH Zurich Johannes Wikner kunye Kaveh Razavi kumsebenzi wabo wophando.

Ngokuyinene, I-malware kumatshini inokusebenzisa iRetbleed ukufumana inkumbulo ukuba ayinakufikelela kuyo, njengedatha yekernel yendlela yokusebenza, amagama agqithisiweyo, izitshixo, kunye nezinye iimfihlo. Ngokutsho kwabaphengululi, iSpecter Variant 2 ithathe ithuba lamasebe angathanga ngqo ukuphumeza ukubulawa okuqikelelwayo kwikernel. Amasebe angathanga ngqo aguqulelwe kwi-postbacks kusetyenziswa i-retpoline ukunciphisa iSpecter Variant 2. I-Retbleed ibonisa ukuba iingxelo zembuyekezo ngelishwa zivuza phantsi kweemeko ezithile ezifana namasebe angathanga ngqo.

Oku kuthetha ukuba ngelishwa i-retpoline yaba kukuthomalalisa okunganelanga kwasekuqaleni. Ngokutsho kwabaphandi, I-Retbleed inokuvuza inkumbulo kwi-Intel CPU cores ngesantya sekwaye malunga I-219 bytes ngesekhondi kunye nokuchaneka kwe-98%.

I-exploit inokukhupha inkumbulo engundoqo ye-CPUs ye I-AMD ene-bandwidth ye-3,9 KB ngesekhondi. Abaphandi bathi ikwazile ukufumana kwaye ivuze i-hashi yengcambu yekhompyuter ye-Linux kwimemori yomzimba malunga nemizuzu engama-28 kunye neeprosesa ze-Intel kunye nemizuzu emi-6 kunye neeprosesa ze-Intel AMD.

Inqaku lophando lwabaphandi kunye neposi yebhlog ichaza iimeko ze-microarchitectural eziyimfuneko ukuze kuqhutywe i-Retbleed. Kwi-Intel, imbuyekezo iqala ukuziphatha njengokutsiba okungathanga ngqo xa i-buffer ye-stack buffer, equlethe uqikelelo lwento ekujoliswe kuyo, iyaphuphuma.

"Oku kuthetha ukuba nayiphi na ingxelo esinokuyifumana ngokufowunelwa kwenkqubo ingasetyenziswa, kwaye zininzi," babhala abaphandi. “Sikwafumanise ukuba ii-CPU ze-AMD zibonisa ukutsiba kwesiporho (CVE-2022-23825) - iingqikelelo zesebe ezenzeka nokuba akukho myalelo wesebe ohambelanayo,” bongeze watsho.

Kufuneka kuqatshelwe ukuba izixokelelwano zeWindows azichaphazeleki, njengoko ezi nkqubo zingagqibekanga kwiNgcaciso eThintelweyo yeSebe engangqalanga (IBRS), ekwalunciphiso olufumanekayo kubasebenzisi beLinux.

Umthombo: https://comsec.ethz.ch


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