No componente systemd-coredump, que trata dos arquivos core gerados ap\u00f3s a falha de processos, foi identificada uma vulnerabilidade (CVE-2022-4415) que permite a um usu\u00e1rio local n\u00e3o privilegiado determinar o conte\u00fado da mem\u00f3ria de processos privilegiados executados com a flag suid root. A presen\u00e7a do problema na configura\u00e7\u00e3o padr\u00e3o foi confirmada nas distribui\u00e7\u00f5es openSUSE, Arch, Debian, Fedora e SLES. <\/p>\n
A vulnerabilidade \u00e9 causada pela falta de um tratamento adequado do par\u00e2metro sysctl fs.suid_dumpable no systemd-coredump, que, com o valor padr\u00e3o definido como 2, permite a gera\u00e7\u00e3o de core dumps para processos com a flag suid. Assume-se que os arquivos core gravados pelo kernel para processos suid devem ter permiss\u00f5es que restrinjam a leitura apenas ao usu\u00e1rio root. A ferramenta systemd-coredump, chamada pelo kernel para salvar os arquivos core, salva o arquivo core sob o identificador root, mas tamb\u00e9m fornece acesso aos arquivos core com base em ACL, permitindo a leitura com base no identificador do propriet\u00e1rio que originalmente iniciou o processo. <\/p>\n
Essa caracter\u00edstica permite que arquivos core sejam carregados sem considerar que o programa pode mudar o identificador do usu\u00e1rio e ser executado com privil\u00e9gios elevados. O ataque consiste em que o usu\u00e1rio pode iniciar um aplicativo suid e enviar a ele um sinal SIGSEGV, ap\u00f3s o qual poder\u00e1 carregar o conte\u00fado do arquivo core, que inclui um corte da mem\u00f3ria do processo no momento da falha. <\/p>\n
Por exemplo, o usu\u00e1rio pode executar «\\\/usr\\\/bin\\\/su» e em outro terminal encerrar sua execu\u00e7\u00e3o com o comando «kill -s SIGSEGV `pidof su`», ap\u00f3s o qual o systemd-coredump salvar\u00e1 o arquivo core no diret\u00f3rio \\\/var\\\/lib\\\/systemd\\\/coredump, configurando para ele um ACL que permite a leitura ao usu\u00e1rio atual. Como a ferramenta suid ‘su’ l\u00ea o conte\u00fado de \\\/etc\\\/shadow, o invasor pode obter acesso \u00e0s informa\u00e7\u00f5es sobre os hashes das senhas de todos os usu\u00e1rios no sistema. A ferramenta sudo n\u00e3o est\u00e1 vulner\u00e1vel a esse ataque, pois pro\u00edbe a gera\u00e7\u00e3o de arquivos core atrav\u00e9s do ulimit. <\/p>\n
De acordo com os desenvolvedores do systemd, a vulnerabilidade se manifesta a partir da vers\u00e3o 247 do systemd (novembro de 2020), mas segundo o pesquisador que identificou o problema, a vers\u00e3o 246 tamb\u00e9m est\u00e1 sujeita \u00e0 vulnerabilidade. A vulnerabilidade ocorre se o systemd for compilado com a biblioteca libacl (que vem por padr\u00e3o em todas as distribui\u00e7\u00f5es populares). Uma corre\u00e7\u00e3o est\u00e1 atualmente dispon\u00edvel na forma de um patch. \u00c9 poss\u00edvel acompanhar a corre\u00e7\u00e3o nas distribui\u00e7\u00f5es nas seguintes p\u00e1ginas: Debian, Ubuntu, Gentoo, RHEL, SUSE, Fedora, Gentoo, Arch. Como uma medida tempor\u00e1ria de prote\u00e7\u00e3o, pode-se definir o sysctl fs.suid_dumpable para 0, desativando a transfer\u00eancia de dumps para o manipulador systemd-coredump. \u0412 \u043a\u043e\u043c\u043f\u043e\u043d\u0435\u043d\u0442\u0435 systemd-coredump, \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0438\u0432\u0430\u044e\u0449\u0435\u043c \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0443 core-\u0444\u0430\u0439\u043b\u043e\u0432, \u0433\u0435\u043d\u0435\u0440\u0438\u0440\u0443\u0435\u043c\u044b\u0445 \u043f\u043e\u0441\u043b\u0435 \u0430\u0432\u0430\u0440\u0438\u0439\u043d\u043e\u0433\u043e \u0437\u0430\u0432\u0435\u0440\u0448\u0435\u043d\u0438\u044f \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u0432, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2022-4415), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u043c\u0443 \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0438\u0442\u044c \u0441\u043e\u0434\u0435\u0440\u0436\u0438\u043c\u043e\u0435 \u043f\u0430\u043c\u044f\u0442\u0438 \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u044b\u0445 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u0432, \u0437\u0430\u043f\u0443\u0449\u0435\u043d\u043d\u044b\u0445 \u0441 \u0444\u043b\u0430\u0433\u043e\u043c suid root. \u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u0432 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u0438 \u043f\u043e \u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e \u043f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u043e \u0432 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 openSUSE, Arch, Debian, Fedora \u0438 SLES. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432\u044b\u0437\u0432\u0430\u043d\u0430 \u043e\u0442\u0441\u0443\u0442\u0441\u0442\u0432\u0438\u0435\u043c \u043a\u043e\u0440\u0440\u0435\u043a\u0442\u043d\u043e\u0439 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0438 sysctl-\u043f\u0430\u0440\u0430\u043c\u0435\u0442\u0440\u0430 fs.suid_dumpable \u0432 systemd-coredump, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u043f\u0440\u0438 \u0432\u044b\u0441\u0442\u0430\u0432\u043b\u0435\u043d\u043d\u043e\u043c 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Fonte: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"