{"id":104043,"date":"2022-05-15T09:36:47","date_gmt":"2022-05-15T07:36:48","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-python-pozvolyayushhaya-vyzvat-sistemnye-komandy-iz-izolirovannyh-skriptov"},"modified":"2022-05-15T09:36:47","modified_gmt":"2022-05-15T07:36:48","slug":"uyazvimost-v-python-pozvolyayushhaya-vyzvat-sistemnye-komandy-iz-izolirovannyh-skriptov","status":"publish","type":"post","link":"https:\/\/prohoster.info\/pt\/blog\/news\/uyazvimost-v-python-pozvolyayushhaya-vyzvat-sistemnye-komandy-iz-izolirovannyh-skriptov","title":{"rendered":"Vulnerabilidade no Python que permite executar comandos do sistema a partir de scripts isolados","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Foi publicado um m\u00e9todo de contorno para sistemas de execu\u00e7\u00e3o isolada de c\u00f3digo em Python, baseado em um erro antigo, que surgiu no Python 2.7, identificado em 2012 e ainda n\u00e3o corrigido no Python 3. Esse erro permite, por meio de um c\u00f3digo especialmente elaborado em Python, iniciar um acesso \u00e0 mem\u00f3ria j\u00e1 liberada (Use-After-Free) no CPython. Inicialmente, acreditava-se que esse erro n\u00e3o apresentava uma amea\u00e7a \u00e0 seguran\u00e7a e que apenas em casos muito raros, normalmente artificiais, poderia levar a um encerramento an\u00f4malo do script. <\/p>\n

Um pesquisador de seguran\u00e7a com o pseud\u00f4nimo kn32 se interessou pelo problema e conseguiu preparar um exploit funcional que permite chamar qualquer comando do sistema, sem ter acesso direto a m\u00e9todos como os.system. O exploit \u00e9 implementado em Python puro e funciona sem a importa\u00e7\u00e3o de bibliotecas externas ou a instala\u00e7\u00e3o do manipulador 'code.__new__'. Apenas o 'builtin.__id__' \u00e9 utilizado como hook, que geralmente n\u00e3o \u00e9 proibido. Do ponto de vista pr\u00e1tico, o c\u00f3digo proposto pode ser usado para contornar mecanismos de isolamento em v\u00e1rios servi\u00e7os e ambientes (como em ambientes de treinamento, shells online, manipuladores embarcados etc.), que permitem a execu\u00e7\u00e3o de c\u00f3digo em Python, mas restringem as chamadas dispon\u00edveis e n\u00e3o permitem o acesso a m\u00e9todos como os.system. <\/p>\n

O c\u00f3digo proposto \u00e9 an\u00e1logo \u00e0 chamada de os.system, funcionando atrav\u00e9s da explora\u00e7\u00e3o de uma vulnerabilidade no CPython. O exploit \u00e9 compat\u00edvel com todas as vers\u00f5es do Python 3 em sistemas com arquitetura x86-64 e demonstra opera\u00e7\u00e3o est\u00e1vel no Ubuntu 22.04, mesmo com os modos de prote\u00e7\u00e3o PIE, RELRO e CET ativados. A opera\u00e7\u00e3o consiste em obter do c\u00f3digo em Python informa\u00e7\u00f5es sobre o endere\u00e7o de uma das fun\u00e7\u00f5es no c\u00f3digo execut\u00e1vel do CPython. Com base nesse endere\u00e7o, \u00e9 calculado o endere\u00e7o base do CPython na mem\u00f3ria e o endere\u00e7o da fun\u00e7\u00e3o system() na inst\u00e2ncia do libc carregada na mem\u00f3ria. No final, \u00e9 feito um salto direto para um endere\u00e7o espec\u00edfico da system, substituindo o ponteiro do primeiro argumento pela string '\/bin\/sh'.

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

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[…]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":104044,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-104043","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Vulnerabilidade no Python que permite executar comandos do sistema a partir de scripts isolados | ProHoster","description":"Foi publicado um m\u00e9todo de contorno para sistemas de execu\u00e7\u00e3o isolada de c\u00f3digo em Python, baseado em um erro antigo, que surgiu no Python 2.7, identificado em 2012 e ainda n\u00e3o 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