{"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\/fr\/blog\/news\/uyazvimost-v-yadre-linux-pozvolyayushhaya-povysit-svoi-privilegii-cherez-bpf","title":{"rendered":"Une vuln\u00e9rabilit\u00e9 dans le noyau Linux permettant d'\u00e9lever ses privil\u00e8ges via BPF","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Publi\u00e9<\/a><\/noindex> d\u00e9tails sur la vuln\u00e9rabilit\u00e9 (CVE-2020-8835<\/a><\/noindex>) dans le noyau Linux, qui a \u00e9t\u00e9 utilis\u00e9e lors de la comp\u00e9tition Pwn2Own 2020<\/a><\/noindex> pour d\u00e9montrer le piratage d'Ubuntu. La vuln\u00e9rabilit\u00e9 a permis \u00e0 un utilisateur non privil\u00e9gi\u00e9 d'obtenir des droits root. Un exploit fonctionnel existe, mais n'est pas encore publi\u00e9. La vuln\u00e9rabilit\u00e9 se trouve dans le sous-syst\u00e8me eBPF, qui permet d'ex\u00e9cuter des gestionnaires pour le tra\u00e7age, l'analyse des performances des sous-syst\u00e8mes et la gestion du trafic, ex\u00e9cut\u00e9s au sein du noyau dans une machine virtuelle sp\u00e9ciale avec JIT.<\/p>\n

Le probl\u00e8me est caus\u00e9 par une erreur dans la fonction __reg_bound_offset32(), utilis\u00e9e pour v\u00e9rifier les op\u00e9rations 32 bits dans le bytecode BPF. En raison d'un calcul incorrect des limites du registre, des conditions pour lire et \u00e9crire des donn\u00e9es en dehors du tampon allou\u00e9 dans la m\u00e9moire du noyau sont survenues lors du traitement des applications BPF sp\u00e9cialement con\u00e7ues. Le probl\u00e8me est apparu dans le noyau 5.5 et, lors du backport des corrections, a \u00e9t\u00e9 transf\u00e9r\u00e9 dans le noyau 5.4, ainsi que dans le paquet avec le noyau 5.3<\/a><\/noindex>, propos\u00e9 dans Ubuntu Linux.<\/p>\n

Pour bloquer la vuln\u00e9rabilit\u00e9, il est recommand\u00e9 de revenir<\/a><\/noindex> sur le patch probl\u00e9matique ou d'interdire l'ex\u00e9cution des applications BPF par des utilisateurs non privil\u00e9gi\u00e9s en r\u00e9glant sysctl kernel.unprivileged_bpf_disabled sur 1. Statut de la correction dans les distributions : Ubuntu<\/a><\/noindex>, Debian<\/a><\/noindex>, Arch<\/a><\/noindex>, Fedora<\/a><\/noindex> et SUSE<\/a><\/noindex> (dans les noyaux RHEL<\/a><\/noindex> le changement probl\u00e9matique n'a pas \u00e9t\u00e9 port\u00e9).<\/p>\n

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

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

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