{"id":114581,"date":"2024-03-26T12:25:42","date_gmt":"2024-03-26T10:25:43","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/zenhammer-metod-ataki-dlya-iskazheniya-soderzhimogo-pamyati-na-platformah-amd-zen"},"modified":"2024-03-26T12:25:42","modified_gmt":"2024-03-26T10:25:43","slug":"zenhammer-metod-ataki-dlya-iskazheniya-soderzhimogo-pamyati-na-platformah-amd-zen","status":"publish","type":"post","link":"https:\/\/prohoster.info\/hr\/blog\/news\/zenhammer-metod-ataki-dlya-iskazheniya-soderzhimogo-pamyati-na-platformah-amd-zen","title":{"rendered":"ZenHammer \u2014 metoda napada za iskrivljavanje sadr\u017eaja memorije na platformama AMD Zen","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Istra\u017eiva\u010di s Tehni\u010dkog sveu\u010dili\u0161ta u Zurichu razvili su ZenHammer napad, koji je varijanta RowHammer napada za promjenu sadr\u017eaja pojedinih bitova dinami\u010dke radne memorije (DRAM), prilago\u0111ena za kori\u0161tenje na platformama s AMD procesorima. Raniji RowHammer napadi bili su ograni\u010deni na sustave s Intel procesorima, ali istra\u017eivanje je pokazalo da se izobli\u010denja memorijskih \u0107elija tako\u0111er mogu posti\u0107i na platformama s AMD kontrolerima memorije. <\/p>\n

Rad metode demonstriran je na AMD Zen 2 i Zen 3 sustavima s DDR4 memorijom od tri vode\u0107a proizvo\u0111a\u010da (Samsung, Micron i SK Hynix). Napad uspje\u0161no zaobilazi implementirani mehanizam TRR (Target Row Refresh) u memorijskim \u010dipovima, koji je usmjeren na za\u0161titu od izobli\u010denja memorijskih \u0107elija u susjednim redovima. Prema procjenama istra\u017eiva\u010da, sustavi temeljen na CPU AMD Zen 3 su vi\u0161e ranjivi nego sustavi s Intel Coffee Lake procesorima, i lak\u0161e ih je i u\u010dinkovitije napasti. Na AMD Zen 2 sustavima, izobli\u010denja \u0107elija postignuta su na 7 od 10 testiranih DDR4 \u010dipova, dok su na Zen 3 sustavima postignuta na 6 od 10. Istra\u017eiva\u010di su tako\u0111er analizirali mogu\u0107nost napada na AMD Zen 4 sustave s DDR5 memorijom, ali metoda napada razvijena za DDR4 uspje\u0161no je reprodukovana samo na 1 od 10 testiranih DDR5 \u010dipova, pri \u010demu sama mogu\u0107nost napada nije isklju\u010dena, ali zahtijeva razvoj u\u010dinkovitijih obrazaca \u010ditanja pogodnih za DDR5 ure\u0111aje. <\/p>\n

Za rad s AMD \u010dipovima uspjeli smo prilagoditi ranije razvijene eksploite koji mijenjaju sadr\u017eaj unosa u tablici stranica memorije (PTE, page table entry) kako bismo stekli privilegije jezgre, zaobilaze\u0107i provjeru lozinke\/ovla\u0161tenja putem modifikacije memorije procesa sudo i o\u0161te\u0107uju\u0107i pohranjeni otvoreni klju\u010d RSA-2048 u OpenSSH kako bismo rekonstruirali privatni klju\u010d. Napad na stranice memorije uspjelo je reproducirati na 7 od 10 testiranih DDR4 \u010dipova, napad na RSA klju\u010d \u2014 na 6 \u010dipova, dok je napad na sudo izveden na 4 \u010dipa, pri \u010demu je vrijeme napada iznosilo 164, 267 i 209 sekundi.

\"ZenHammer<\/center> <\/p>\n

Metoda se tako\u0111er mo\u017ee primijeniti za napad na sustav putem preglednika, radi uno\u0161enja izmjena iz virtualnih ma\u0161ina<\/a> ili za organizaciju napada putem mre\u017ee. Na GitHubu pod MIT licencom objavljen je izvorni kod alata DARE za obrnutu in\u017eenjering raspodjele adresa u DRAM memoriji, kao i dva seta alata za fuzzing-testiranje izobli\u010denja bitova u memoriji \u2014 ddr4_zen2_zen3_pub za DDR4 \u010dipove (Zen 2 i Zen 3) i ddr5_zen4_pub za DDR5 \u010dipove (Zen 4), koji se mogu koristiti za provjeru vlastitih sustava na podlo\u017enost napadima.

\"ZenHammer<\/center> <\/p>\n

Za iskrivljenje bitova primjenjuje se metoda RowHammer, koja se temelji na tome da u DRAM memoriji, koja predstavlja dvodimenzionalnu mre\u017eu \u0107elija sastavljenih od kondenzatora i tranzistora, neprekidno \u010ditanje istog podru\u010dja memorije dovodi do fluktuacije napona i anomalija, uzrokuju\u0107i malu izgubljenost naboja susjednih \u0107elija. Ako je intenzitet \u010ditanja velik, susjedna \u0107elija mo\u017ee izgubiti dovoljno velike koli\u010dine naboja i sljede\u0107i ciklus regeneracije ne uspijevaju vratiti njezino prvotno stanje, \u0161to dovodi do promjene vrijednosti spremljenog u toj \u0107eliji. U istra\u017eivanju su otkrivene osobitosti mehanizama mapiranja fizi\u010dke memorije i sinkronizacije s a\u017euriranjem memorije koje se koriste u AMD procesorima, omogu\u0107iv\u0161i rekonstrukciju niskonivoe adresacije DRAM-a, odre\u0111ivanje adresa susjednih \u0107elija, razvoj metoda za zaobila\u017eenje ke\u0161iranja, kao i izra\u010dun obrazaca i frekvencije operacija koje dovode do gubitka naboja. <\/p>\n

Za za\u0161titu od RowHammer proizvo\u0111a\u010di \u010dipova primjenjuju mehanizam TRR (Target Row Refresh), koji blokira iskrivljenje \u0107elija u posebnim slu\u010dajevima, ali ne \u0161titi od svih mogu\u0107ih varijanti napada. Najefikasnija metoda za\u0161tite ostaje kori\u0161tenje memorije s kodovima korekcije gre\u0161aka (ECC), koja zna\u010dajno ote\u017eava, ali potpuno ne isklju\u010duje provo\u0111enje napada klase RowHammer. Smanjenje vjerojatnosti uspje\u0161nog napada tako\u0111er omogu\u0107uje pove\u0107anje frekvencije regeneracije memorije. <\/p>\n

Tvrtka AMD objavila je izvje\u0161taj o problemu, u kojem se navodi da se u AMD procesorima koriste kontroleri memorije koji odgovaraju DDR specifikacijama, a budu\u0107i da uspje\u0161nost napada ovisi uglavnom o postavkama sustava i DRAM memoriji, pitanja o uklanjanju problema treba postaviti proizvo\u0111a\u010dima memorije i sustava. Me\u0111u postoje\u0107im metodama za ote\u017eavanje izvo\u0111enja Rowhammer napada spominje se kori\u0161tenje ECC memorije, pove\u0107anje u\u010destalosti regeneracije memorije, isklju\u010divanje moda odgo\u0111ene regeneracije i kori\u0161tenje procesora s kontrolerima koji podr\u017eavaju MAC (Maximum Activate Count) re\u017eim za DDR4 (1., 2. i 3. generacija AMD EPYC 'Naples', 'Rome' i 'Milan') te RFM (Refresh Management) za DDR5 (4. generacija AMD EPYC).
\n
Izvor: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0418\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u0438 \u0438\u0437 \u0428\u0432\u0435\u0439\u0446\u0430\u0440\u0441\u043a\u043e\u0439 \u0432\u044b\u0441\u0448\u0435\u0439 \u0442\u0435\u0445\u043d\u0438\u0447\u0435\u0441\u043a\u043e\u0439 \u0448\u043a\u043e\u043b\u044b \u0426\u044e\u0440\u0438\u0445\u0430 \u0440\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u0430\u043b\u0438 \u043c\u0435\u0442\u043e\u0434 \u0430\u0442\u0430\u043a\u0438 ZenHammer, \u043f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u043b\u044f\u044e\u0449\u0438\u0439 \u0441\u043e\u0431\u043e\u0439 \u0432\u0430\u0440\u0438\u0430\u043d\u0442 \u0430\u0442\u0430\u043a \u043a\u043b\u0430\u0441\u0441\u0430 RowHammer \u0434\u043b\u044f \u0438\u0437\u043c\u0435\u043d\u0435\u043d\u0438\u044f \u0441\u043e\u0434\u0435\u0440\u0436\u0438\u043c\u043e\u0433\u043e \u043e\u0442\u0434\u0435\u043b\u044c\u043d\u044b\u0445 \u0431\u0438\u0442\u043e\u0432 \u0434\u0438\u043d\u0430\u043c\u0438\u0447\u0435\u0441\u043a\u043e\u0439 \u043e\u043f\u0435\u0440\u0430\u0442\u0438\u0432\u043d\u043e\u0439 \u043f\u0430\u043c\u044f\u0442\u0438 (DRAM), \u0430\u0434\u0430\u043f\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u044b\u0439 \u0434\u043b\u044f \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u044f \u043d\u0430 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u0430\u0445 \u0441 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u0440\u0430\u043c\u0438 AMD. \u041f\u0440\u043e\u0448\u043b\u044b\u0435 \u043c\u0435\u0442\u043e\u0434\u044b \u0430\u0442\u0430\u043a \u043a\u043b\u0430\u0441\u0441\u0430 RowHammer \u043e\u0433\u0440\u0430\u043d\u0438\u0447\u0438\u0432\u0430\u043b\u0438\u0441\u044c \u0441\u0438\u0441\u0442\u0435\u043c\u0430\u043c\u0438 \u043d\u0430 \u0431\u0430\u0437\u0435 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u0440\u043e\u0432 Intel, \u043d\u043e \u043f\u0440\u043e\u0432\u0435\u0434\u0451\u043d\u043d\u043e\u0435 \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u043d\u0438\u0435 \u043f\u043e\u043a\u0430\u0437\u0430\u043b\u043e, \u0447\u0442\u043e \u0438\u0441\u043a\u0430\u0436\u0435\u043d\u0438\u044f \u044f\u0447\u0435\u0435\u043a \u043f\u0430\u043c\u044f\u0442\u0438 \u0442\u0430\u043a\u0436\u0435 \u043c\u043e\u0436\u043d\u043e […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":114582,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-114581","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47ZenHammer \u2014 metoda napada za iskrivljavanje sadr\u017eaja memorije na platformama AMD Zen | ProHoster","description":"Istra\u017eiva\u010di sa \u0160vicarskog federalnog instituta tehnologije u Z\u00fcrichu razvili su metodu napada ZenHammer, koja predstavlja varijantu RowHammer napada za promjenu sadr\u017eaja pojedinih bitova dinami\u010dke operativne 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