{"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\/pt\/blog\/news\/uyazvimost-v-yadre-linux-pozvolyayushhaya-povysit-svoi-privilegii-cherez-bpf","title":{"rendered":"Uma vulnerabilidade no n\u00facleo do Linux, que permite o aumento de privil\u00e9gios atrav\u00e9s do BPF.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Publicado<\/a><\/noindex> informa\u00e7\u00f5es sobre a vulnerabilidade (CVE-2020-8835<\/a><\/noindex>) no n\u00facleo do Linux, que foi utilizada em uma competi\u00e7\u00e3o Pwn2Own 2020<\/a><\/noindex> para demonstrar a invas\u00e3o do Ubuntu. A vulnerabilidade permitiu que um usu\u00e1rio n\u00e3o privilegiado obtivesse privil\u00e9gios de root. Um exploit funcional existe, mas ainda n\u00e3o foi publicado. Essa vulnerabilidade est\u00e1 presente na subsistema eBPF, que permite executar manipuladores para rastreamento, an\u00e1lise de desempenho de subsistemas e gerenciamento de tr\u00e1fego, sendo executados dentro do n\u00facleo em uma m\u00e1quina virtual especial com JIT.<\/p>\n

O problema \u00e9 causado por um erro na fun\u00e7\u00e3o __reg_bound_offset32(), que \u00e9 utilizada para verificar opera\u00e7\u00f5es de 32 bits no bytecode BPF. Devido ao c\u00e1lculo incorreto dos limites do registrador, ao processar aplicativos BPF cuidadosamente formatados, surgiram condi\u00e7\u00f5es para ler e gravar dados fora do buffer alocado na \u00e1rea de mem\u00f3ria do n\u00facleo. O problema surgiu no n\u00facleo 5.5 e, posteriormente, ao portar corre\u00e7\u00f5es, foi transferido para o n\u00facleo 5.4, assim como em o pacote com n\u00facleo 5.3<\/a><\/noindex>, que \u00e9 oferecido no Ubuntu Linux.<\/p>\n

Para bloquear a vulnerabilidade, \u00e9 recomendado reverter<\/a><\/noindex> o patch problem\u00e1tico ou proibir a execu\u00e7\u00e3o de aplicativos BPF por usu\u00e1rios n\u00e3o privilegiados configurando o sysctl kernel.unprivileged_bpf_disabled para o valor 1. O status da corre\u00e7\u00e3o nas distribui\u00e7\u00f5es: Ubuntu<\/a><\/noindex>, Debian<\/a><\/noindex>, Arch<\/a><\/noindex>, Fedora<\/a><\/noindex> e SUSE<\/a><\/noindex> (no n\u00facleo, RHEL<\/a><\/noindex> a modifica\u00e7\u00e3o problem\u00e1tica n\u00e3o foi transferida).<\/p>\n

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

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

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