{"id":82556,"date":"2020-05-22T19:41:55","date_gmt":"2020-05-22T17:41:55","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/kriticheskaya-uyazvimost-v-realizaczii-funkczii-memcpy-dlya-armv7-iz-sostava-glibc"},"modified":"2020-05-22T19:41:55","modified_gmt":"2020-05-22T17:41:55","slug":"kriticheskaya-uyazvimost-v-realizaczii-funkczii-memcpy-dlya-armv7-iz-sostava-glibc","status":"publish","type":"post","link":"https:\/\/prohoster.info\/pt\/blog\/news\/kriticheskaya-uyazvimost-v-realizaczii-funkczii-memcpy-dlya-armv7-iz-sostava-glibc","title":{"rendered":"Vulnerabilidade cr\u00edtica na implementa\u00e7\u00e3o da fun\u00e7\u00e3o memcpy para ARMv7 do Glibc","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Pesquisadores de seguran\u00e7a da Cisco revelaram<\/a><\/noindex> detalhes no aplicativo para Windows, que permitia ao usu\u00e1rio elevar seus privil\u00e9gios no sistema para administrador (a vulnerabilidade foi causada pela intera\u00e7\u00e3o inadequada entre o cliente GUI sem privil\u00e9gios e o servi\u00e7o de sistema).<\/a><\/noindex> (CVE-2020-6096<\/a><\/noindex>) na implementa\u00e7\u00e3o da fun\u00e7\u00e3o memcpy() fornecida na Glibc para a plataforma ARMv7 de 32 bits. O problema \u00e9 causado pelo tratamento inadequado de valores negativos do par\u00e2metro que define o tamanho da \u00e1rea a ser copiada, devido ao uso de otimiza\u00e7\u00f5es em assembly que manipulam inteiros de 32 bits com sinal. A chamada memcpy() em sistemas ARMv7 com tamanho negativo resulta em compara\u00e7\u00f5es incorretas e grava\u00e7\u00f5es fora dos limites do buffer especificado.<\/p>\n

A vulnerabilidade pode ser explorada para executar c\u00f3digo em situa\u00e7\u00f5es em que um invasor possa induzir a forma\u00e7\u00e3o de um valor negativo para a vari\u00e1vel que determina o tamanho dos dados copiados (por exemplo, um n\u00famero negativo pode ocorrer ao transferir mais de 2 GB de dados, mas para a explora\u00e7\u00e3o, \u00e9 necess\u00e1rio enviar pelo menos 4 GB para ultrapassar os limites do buffer). A fun\u00e7\u00e3o memcpy() \u00e9 amplamente utilizada em aplica\u00e7\u00f5es, e os processadores ARMv7 s\u00e3o comuns em sistemas automotivos, dispositivos m\u00f3veis, industriais, de consumo, de comunica\u00e7\u00e3o e embarcados, que podem potencialmente ser alvos de ataques atrav\u00e9s de Bluetooth, HD Radio\/DAB, USB, CAN bus, Wi-Fi e outras fontes de dados externas (por exemplo, servi\u00e7os e aplica\u00e7\u00f5es acess\u00edveis pela rede que aceitam dados sem restri\u00e7\u00e3o de tamanho podem ser atacadas).<\/p>\n

Como exemplo, \u00e9 apresentado o desenvolvimento de um exploit funcional para atacar um servidor http incorporado nos sistemas de informa\u00e7\u00e3o automotivos, acess\u00edvel atrav\u00e9s da rede Wi-Fi do ve\u00edculo. Um invasor externo pode explorar a vulnerabilidade na fun\u00e7\u00e3o memcpy deste servidor enviando uma solicita\u00e7\u00e3o GET de tamanho muito grande e obter acesso root ao sistema.<\/p>\n

\"Vulnerabilidade<\/a><\/noindex><\/center><\/p>\n

Em sistemas x86 de 32 bits, o problema n\u00e3o se manifesta, pois a implementa\u00e7\u00e3o da memcpy para esta arquitetura interpreta corretamente a vari\u00e1vel de tamanho como um valor inteiro sem sinal do tipo size_t (na escrita em assembly, implementa\u00e7\u00e3o<\/a><\/noindex> para ARMv7 \u00e9 tratado como inteiro com sinal). A corre\u00e7\u00e3o est\u00e1 dispon\u00edvel no formato patch<\/a><\/noindex>, que far\u00e1 parte da atualiza\u00e7\u00e3o de agosto da Glibc 2.32.
\nA corre\u00e7\u00e3o consiste em substituir o uso de instru\u00e7\u00f5es assembly que operam com operandos com sinal (bge e blt) por suas equivalentes sem sinal (blo e bhs). <\/p>\n

O problema ainda n\u00e3o foi resolvido em Debian 9 e 10<\/a><\/noindex> (n\u00e3o se manifesta no Debian 8), Fedora<\/a><\/noindex>, Ubuntu<\/a><\/noindex>, OpenEmbedded, Tizen (utiliza glibc). RHEL<\/a><\/noindex> e SUSE<\/a><\/noindex> o problema n\u00e3o se aplica, uma vez que eles n\u00e3o suportam sistemas ARMv7 de 32 bits. O Android n\u00e3o \u00e9 vulner\u00e1vel, pois utiliza sua pr\u00f3pria implementa\u00e7\u00e3o da libc (Bionic). Em OpenWRT<\/a><\/noindex> a maioria das compila\u00e7\u00f5es utiliza Musl por padr\u00e3o, mas o reposit\u00f3rio tamb\u00e9m cont\u00e9m glibc.<\/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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[…]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":82557,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-82556","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\udd47 Vulnerabilidade cr\u00edtica na implementa\u00e7\u00e3o da fun\u00e7\u00e3o memcpy para ARMv7 a partir do Glibc | ProHoster","description":"Pesquisadores de seguran\u00e7a da Cisco revelaram 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