DDR4 memory chips imakhalabe pachiwopsezo cha RowHammer ngakhale chitetezo chowonjezera

Gulu la ofufuza ochokera ku Vrije Universiteit Amsterdam, ETH Zurich ndi Qualcomm kuwononga kuphunzira za momwe chitetezo chimagwirira ntchito m'magulu amakono a DDR4 memory chips Chitsogozo, kukulolani kuti musinthe zomwe zili mumtundu umodzi wa dynamic random access memory (DRAM). Zotsatira zake zinali zokhumudwitsa ndipo tchipisi ta DDR4 kuchokera kwa opanga akuluakulu akadali khalani osatetezeka (CVE-2020-10255).

Chiwopsezo cha RowHammer chimalola zomwe zili m'makumbukidwe amunthu aliyense kuti zisokonezeke powerenga mozungulira deta kuchokera ku ma cell oyandikana nawo. Popeza kukumbukira kwa DRAM ndi ma cell amitundu iwiri, iliyonse imakhala ndi capacitor ndi transistor, kuwerengera mosalekeza kwa dera lomwelo la kukumbukira kumabweretsa kusinthasintha kwamagetsi ndi zolakwika zomwe zimapangitsa kutayika pang'ono kwa ma cell oyandikana nawo. Ngati kuchuluka kwa kuwerenga kuli kokwanira, ndiye kuti selo likhoza kutaya ndalama zambiri zokwanira ndipo kusinthika kotsatira kudzakhala ndi nthawi yobwezeretsa chikhalidwe chake choyambirira, chomwe chidzatsogolera kusintha kwa mtengo wa deta yosungidwa mu selo. .

Kuti aletse izi, tchipisi tamakono ta DDR4 timagwiritsa ntchito ukadaulo wa TRR (Target Row Refresh), wopangidwa kuti aletse ma cell kuti asokonezeke pakuwukira kwa RowHammer. Vuto ndiloti palibe njira imodzi yogwiritsira ntchito TRR ndipo CPU iliyonse ndi wopanga kukumbukira amatanthauzira TRR m'njira yakeyake, amagwiritsa ntchito njira zake zodzitetezera ndipo samaulula tsatanetsatane wa kukhazikitsa.
Kuwerenga njira zotsekera za RowHammer zomwe opanga amapanga zidapangitsa kuti zikhale zosavuta kupeza njira zolambalala chitetezo. Ataunika, zidapezeka kuti mfundo yopangidwa ndi opanga "chitetezo kudzera mosadziwika bwino (chitetezo ndi kusawoneka) pokhazikitsa TRR imathandiza kokha pachitetezo pazochitika zapadera, kuphimba kuukira komwe kumayendetsa kusintha kwa ma cell mumizere imodzi kapena iwiri yoyandikana.

Zomwe zimagwiritsidwa ntchito ndi ochita kafukufuku zimapangitsa kuti zitheke kuyang'ana kutengeka kwa tchipisi kumitundu yosiyanasiyana ya RowHammer kuukira, komwe kuyesa kukopa kuwongolera kumapangidwira mizere ingapo yama cell kukumbukira nthawi imodzi. Kuwukira kotereku kumatha kudutsa chitetezo cha TRR chokhazikitsidwa ndi opanga ena ndikuyambitsa katangale pang'ono, ngakhale pa hardware yatsopano yokhala ndi kukumbukira kwa DDR4.
Mwa ma DIMM a 42 omwe adaphunziridwa, ma module a 13 adakhala pachiwopsezo chamitundu yosagwirizana ndi RowHammer, ngakhale adalengeza chitetezo. Ma module ovuta adapangidwa ndi SK Hynix, Micron ndi Samsung, omwe adapanga chimakwirira 95% ya msika wa DRAM.

Kuphatikiza pa DDR4, tchipisi ta LPDDR4 zomwe zimagwiritsidwa ntchito pazida zam'manja zidaphunziridwanso, zomwe zidakhalanso zokhudzidwa ndi mitundu yosiyanasiyana ya kuukira kwa RowHammer. Makamaka, kukumbukira komwe kumagwiritsidwa ntchito mu Google Pixel, Google Pixel 3, LG G7, OnePlus 7 ndi Samsung Galaxy S10 mafoni adakhudzidwa ndi vutoli.

Ofufuza adatha kupanganso njira zingapo zopezera ma tchipisi ovuta a DDR4. Mwachitsanzo, kugwiritsa ntchito RowHammer-dyera masuku pamutu kwa PTE (Zolemba Patsamba la Tsamba) zidatenga kuchokera ku masekondi 2.3 mpaka maola atatu ndi masekondi khumi ndi asanu kuti apeze mwayi wa kernel, kutengera tchipisi toyesedwa. Kuukira pakuwonongeka kwa kiyi yapagulu yosungidwa kukumbukira, RSA-2048 idatenga masekondi 74.6 mpaka 39 mphindi 28 masekondi. Kuukira zidatenga mphindi 54 ndi masekondi 16 kuti zidutse cheke posintha kukumbukira njira ya sudo.

Ntchito yasindikizidwa kuti iwonetsere ma DDR4 memory chips omwe ogwiritsa ntchito amagwiritsa ntchito TRRespass. Kuti muthe kuchita bwino kuukira, chidziwitso chokhudza masanjidwe a maadiresi omwe amagwiritsidwa ntchito muzowongolera kukumbukira pokhudzana ndi mabanki ndi mizere yama cell a kukumbukira ndikofunikira. Chida chapangidwanso kuti chizindikire masanjidwewo sewero, zomwe zimafuna kuthamanga ngati mizu. Posachedwapanso anakonza sindikizani pulogalamu yoyesa kukumbukira kukumbukira kwa smartphone.

Makampani Intel и AMD Kuti atetezedwe, adalangiza kugwiritsa ntchito kukumbukira zolakwika (ECC), owongolera kukumbukira omwe ali ndi chithandizo cha Maximum Activate Count (MAC), ndikugwiritsa ntchito kuchuluka kotsitsimula. Ofufuza akukhulupirira kuti tchipisi tatulutsidwa kale palibe njira yothetsera chitetezo chotsimikizika ku Rowhammer, komanso kugwiritsa ntchito ECC ndikuwonjezera kuchuluka kwa kukumbukira kukumbukira sikunakhale kothandiza. Mwachitsanzo, adafunsidwa kale njira kuukira kukumbukira kwa DRAM kudutsa chitetezo cha ECC, ndikuwonetsanso kuthekera koukira DRAM kudzera netiweki yakomwekokuchokera dongosolo la alendo и mothandizidwa ndi kuthamanga JavaScript mu msakatuli.

Source: opennet.ru