{"id":53866,"date":"2019-12-12T00:00:00","date_gmt":"2019-12-11T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/plundervolt-novyj-metod-ataki-na-protsessory-intel-zatragivayushhij-tehnologiyu-sgx"},"modified":"2020-02-18T14:01:48","modified_gmt":"2020-02-18T11:01:48","slug":"plundervolt-novyj-metod-ataki-na-protsessory-intel-zatragivayushhij-tehnologiyu-sgx","status":"publish","type":"post","link":"https:\/\/prohoster.info\/pt\/blog\/news\/plundervolt-novyj-metod-ataki-na-protsessory-intel-zatragivayushhij-tehnologiyu-sgx","title":{"rendered":"Plundervolt \u2014 um novo m\u00e9todo de ataque a processadores Intel, afetando a tecnologia SGX","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

A Intel lan\u00e7ou<\/a><\/noindex> atualiza\u00e7\u00e3o de microc\u00f3digo que corrige uma vulnerabilidade<\/a><\/noindex> (CVE-2019-14607), permitindo<\/a><\/noindex> via manipula\u00e7\u00f5es no mecanismo de controle din\u00e2mico da tens\u00e3o e frequ\u00eancia da CPU, iniciar a corrup\u00e7\u00e3o do conte\u00fado das c\u00e9lulas de dados, incluindo aquelas utilizadas em c\u00e1lculos em enclaves isolados do Intel SGX. O ataque foi denominado Plundervolt e potencialmente permite que um usu\u00e1rio local obtenha eleva\u00e7\u00e3o de privil\u00e9gios no sistema, cause nega\u00e7\u00e3o de servi\u00e7o e acesse dados confidenciais.<\/p>\n

O ataque representa um perigo apenas no contexto de manipula\u00e7\u00e3o de c\u00e1lculos em enclaves SGX, pois para sua execu\u00e7\u00e3o requer privil\u00e9gios de root no sistema. Em um cen\u00e1rio simples, o atacante pode causar distor\u00e7\u00f5es nas informa\u00e7\u00f5es processadas no enclave, mas em cen\u00e1rios mais complexos existe a possibilidade de recria\u00e7\u00e3o de chaves privadas armazenadas no enclave, usadas para criptografia com algoritmos RSA-CRT e AES-NI. A t\u00e9cnica tamb\u00e9m pode ser aplicada para gerar erros em algoritmos inicialmente corretos para provocar vulnerabilidades ao lidar com mem\u00f3ria, como o acesso a \u00e1reas al\u00e9m do buffer alocado.
\nProt\u00f3tipo de c\u00f3digo para realizar o ataque foi publicado<\/a><\/noindex> no GitHub<\/p>\n

A ess\u00eancia do m\u00e9todo \u00e9 criar condi\u00e7\u00f5es para surgimento de distor\u00e7\u00f5es imprevistas nos dados durante os c\u00e1lculos em SGX, das quais a implementa\u00e7\u00e3o de criptografia e autentica\u00e7\u00e3o de mem\u00f3ria no enclave n\u00e3o protege. Para introduzir distor\u00e7\u00f5es, foi poss\u00edvel utilizar interfaces de programa\u00e7\u00e3o padr\u00e3o para gerenciar frequ\u00eancia e tens\u00e3o, normalmente aplicadas para reduzir o consumo de energia durante ociosidade do sistema e ativar o m\u00e1ximo desempenho durante tarefas intensivas. As caracter\u00edsticas de frequ\u00eancia e tens\u00e3o abrangem todo o chip, impactando tamb\u00e9m a execu\u00e7\u00e3o de c\u00e1lculos no enclave isolado. <\/p>\n

Ao alterar a tens\u00e3o, \u00e9 poss\u00edvel criar condi\u00e7\u00f5es em que a carga \u00e9 insuficiente para regenerar a c\u00e9lula de mem\u00f3ria dentro da CPU, levando a uma altera\u00e7\u00e3o no seu valor. A principal diferen\u00e7a em rela\u00e7\u00e3o ao ataque RowHammer<\/a><\/noindex> \u00e9 o que RowHammer permite alterar o conte\u00fado de bits individuais na mem\u00f3ria DRAM, atrav\u00e9s da leitura c\u00edclica de dados de c\u00e9lulas vizinhas, enquanto o Plundervolt permite a altera\u00e7\u00e3o de bits dentro da CPU, quando os dados j\u00e1 est\u00e3o carregados da mem\u00f3ria para a execu\u00e7\u00e3o de c\u00e1lculos. Essa caracter\u00edstica permite contornar os mecanismos de controle de integridade e criptografia de dados na mem\u00f3ria aplicados no SGX, j\u00e1 que os valores na mem\u00f3ria permanecem corretos, mas podem ser distorcidos durante opera\u00e7\u00f5es com eles, at\u00e9 que o resultado seja gravado na mem\u00f3ria.<\/p>\n

Se o valor alterado for utilizado em um processo de multiplica\u00e7\u00e3o na criptografia, o resultado ser\u00e1 um texto cifrado incorreto. Tendo a capacidade de acessar o manipulador no SGX para criptografar seus dados, um atacante pode provocar falhas para acumular estat\u00edsticas sobre a altera\u00e7\u00e3o do texto cifrado na sa\u00edda e, em alguns minutos, recuperar o valor da chave armazenada no enclave. O texto original na entrada e o texto cifrado correto na sa\u00edda s\u00e3o conhecidos, a chave n\u00e3o muda, e a sa\u00edda de um texto cifrado incorreto indica a distor\u00e7\u00e3o de algum bit para o oposto. <\/p>\n

Analisando os pares acumulados de valores corretos e distorcidos dos textos cifrados durante v\u00e1rias falhas, usando m\u00e9todos de An\u00e1lise Diferencial de Falhas (DFA, Differential Fault Analysis<\/a><\/noindex>) \u00e9 poss\u00edvel prever<\/a><\/noindex> as chaves prov\u00e1veis usadas para a criptografia sim\u00e9trica AES, e ent\u00e3o, analisando as interse\u00e7\u00f5es das chaves em diferentes conjuntos, determinar a chave procurada.<\/p>\n

\r\n \"Por\r\n
<\/div>\r\n <\/div><\/center><\/p>\n

O problema afeta v\u00e1rios modelos de processadores Intel, incluindo a CPU Intel Core da 6\u00aa \u00e0 10\u00aa gera\u00e7\u00e3o, assim como a 5\u00aa e 6\u00aa gera\u00e7\u00f5es Xeon E3, 1\u00aa e 2\u00aa gera\u00e7\u00f5es Intel Xeon Scalable, Xeon D,
\n Xeon W e Xeon E.
\nLembre-se de que a tecnologia SGX (<\/p>\n

Software Guard Extensions) surgiu nos processadores Intel Core da sexta gera\u00e7\u00e3o (Skylake) e<\/a><\/noindex>) surgiu nos processadores Intel Core de sexta gera\u00e7\u00e3o (Skylake) e oferece<\/a><\/noindex> uma s\u00e9rie de instru\u00e7\u00f5es que permitem isolar \u00e1reas de mem\u00f3ria confidenciais para aplica\u00e7\u00f5es de n\u00edvel do usu\u00e1rio \u2014 enclaves, cujo conte\u00fado n\u00e3o pode ser lido ou modificado mesmo pelo n\u00facleo e pelo c\u00f3digo executado nos modos ring0, SMM e VMM. Transferir o controle para o c\u00f3digo no enclave n\u00e3o \u00e9 poss\u00edvel por meio de fun\u00e7\u00f5es tradicionais de mudan\u00e7a e manipula\u00e7\u00f5es de registradores e pilha \u2014 para transferir o controle para o enclave, uma nova instru\u00e7\u00e3o especialmente criada \u00e9 utilizada, que realiza uma verifica\u00e7\u00e3o de autoriza\u00e7\u00e3o. Nesse contexto, o c\u00f3digo colocado no enclave pode usar m\u00e9todos cl\u00e1ssicos de chamada para acessar fun\u00e7\u00f5es dentro do enclave e uma instru\u00e7\u00e3o especial para chamar fun\u00e7\u00f5es externas. Para prote\u00e7\u00e3o contra ataques de hardware, como a conex\u00e3o ao m\u00f3dulo DRAM, \u00e9 usado criptografia da mem\u00f3ria do enclave.<\/p>\n

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

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

\u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Intel \u0432\u044b\u043f\u0443\u0441\u0442\u0438\u043b\u0430 \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u043c\u0438\u043a\u0440\u043e\u043a\u043e\u0434\u0430, \u0443\u0441\u0442\u0440\u0430\u043d\u044f\u044e\u0449\u0435\u0433\u043e \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2019-14607), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0443\u044e \u0447\u0435\u0440\u0435\u0437 \u043c\u0430\u043d\u0438\u043f\u0443\u043b\u044f\u0446\u0438\u0438 \u0441 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u043e\u043c \u0434\u0438\u043d\u0430\u043c\u0438\u0447\u0435\u0441\u043a\u043e\u0433\u043e \u0443\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u044f \u043d\u0430\u043f\u0440\u044f\u0436\u0435\u043d\u0438\u0435\u043c \u0438 \u0447\u0430\u0441\u0442\u043e\u0442\u043e\u0439 \u0432 CPU \u0438\u043d\u0438\u0446\u0438\u0438\u0440\u043e\u0432\u0430\u0442\u044c \u043f\u043e\u0432\u0440\u0435\u0436\u0434\u0435\u043d\u0438\u0435 \u0441\u043e\u0434\u0435\u0440\u0436\u0438\u043c\u043e\u0433\u043e \u044f\u0447\u0435\u0435\u043a \u0441 \u0434\u0430\u043d\u043d\u044b\u043c\u0438, \u0432 \u0442\u043e\u043c \u0447\u0438\u0441\u043b\u0435 \u0432 \u043e\u0431\u043b\u0430\u0441\u0442\u044f\u0445, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u043c\u044b\u0445 \u043f\u0440\u0438 \u0432\u044b\u0447\u0438\u0441\u043b\u0435\u043d\u0438\u044f\u0445 \u0432 \u0438\u0437\u043e\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u044b\u0445 \u0430\u043d\u043a\u043b\u0430\u0432\u0430\u0445 Intel SGX. \u0410\u0442\u0430\u043a\u0430 \u043f\u043e\u043b\u0443\u0447\u0438\u043b\u0430 \u043d\u0430\u0437\u0432\u0430\u043d\u0438\u0435 Plundervolt, \u0438 \u043f\u043e\u0442\u0435\u043d\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u0434\u043e\u0431\u0438\u0442\u044c\u0441\u044f \u043f\u043e\u0432\u044b\u0448\u0435\u043d\u0438\u044f \u0441\u0432\u043e\u0438\u0445 \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0439 \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435, \u0432\u044b\u0437\u0432\u0430\u0442\u044c […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-53866","post","type-post","status-publish","format-standard","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\udd47Plundervolt \u2014 um novo m\u00e9todo de ataque aos 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