{"id":76196,"date":"2020-03-31T19:42:05","date_gmt":"2020-03-31T17:42:05","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-yadre-linux-pozvolyayushhaya-povysit-svoi-privilegii-cherez-bpf"},"modified":"2020-03-31T19:42:05","modified_gmt":"2020-03-31T17:42:05","slug":"uyazvimost-v-yadre-linux-pozvolyayushhaya-povysit-svoi-privilegii-cherez-bpf","status":"publish","type":"post","link":"https:\/\/prohoster.info\/nl\/blog\/news\/uyazvimost-v-yadre-linux-pozvolyayushhaya-povysit-svoi-privilegii-cherez-bpf","title":{"rendered":"Kwetsbaarheid in de Linux-kernel die privileges kan verhogen via BPF.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Gepubliceerd<\/a><\/noindex> informatie over de kwetsbaarheid (CVE-2020-8835<\/a><\/noindex>) in de Linux-kernel, die werd gebruikt in de competitie Pwn2Own 2020<\/a><\/noindex> tijdens de demonstratie van het hacken van Ubuntu. De kwetsbaarheid stelde een niet-geprivilegieerde gebruiker in staat om rootrechten te verkrijgen. Er bestaat een werkende exploit, maar deze is nog niet gepubliceerd. De kwetsbaarheid is aanwezig in de eBPF-subsysteem, waarmee handlers kunnen worden uitgevoerd voor tracing, analyse van subsystemen en verkeersbeheer, uitgevoerd binnen de kernel in een speciale virtuele machine met JIT.<\/p>\n

Het probleem wordt veroorzaakt door een fout in de functie __reg_bound_offset32(), die wordt toegepast voor het controleren van 32-bits operaties in de BPF-bytecode. Door een onjuiste berekening van de registergrenzen ontstonden er bij het verwerken van speciaal ontworpen BPF-applicaties omstandigheden voor het lezen en schrijven van gegevens buiten de toegewezen buffer in het geheugen van de kernel. Het probleem verscheen in kernel 5.5 en werd later, bij het backporten van de correcties, overgebracht naar kernel 5.4, evenals in de pakket met kernel 5.3<\/a><\/noindex>, aangeboden in Ubuntu Linux.<\/p>\n

Om de kwetsbaarheid te blokkeren, wordt aangeraden om de<\/a><\/noindex> problematische patch terug te draaien of het uitvoeren van BPF-applicaties door niet-geprivilegieerde gebruikers te verbieden door sysctl kernel.unprivileged_bpf_disabled in te stellen op 1. Status van de correctie in distributies: Ubuntu<\/a><\/noindex>, Debian<\/a><\/noindex>, Arch<\/a><\/noindex>, Fedora<\/a><\/noindex> en SUSE<\/a><\/noindex> (in de kernel RHEL<\/a><\/noindex> de problematische wijziging is niet overgebracht).<\/p>\n

<\/a><\/noindex><\/p>\n

Bron: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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