{"id":37225,"date":"2019-10-31T22:16:26","date_gmt":"2019-10-31T19:16:26","guid":{"rendered":"https:\/\/prohoster.info\/blog\/ataka-knob-pozvolyayushhaya-perehvatit-zashifrovannyj-trafik-bluetooth\/"},"modified":"2019-10-31T22:16:26","modified_gmt":"2019-10-31T19:16:26","slug":"ataka-knob-pozvolyayushhaya-perehvatit-zashifrovannyj-trafik-bluetooth","status":"publish","type":"post","link":"https:\/\/prohoster.info\/pt\/blog\/news\/ataka-knob-pozvolyayushhaya-perehvatit-zashifrovannyj-trafik-bluetooth","title":{"rendered":"Ataque KNOB, permitindo interceptar tr\u00e1fego Bluetooth criptografado","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Revelado<\/a><\/noindex> informa\u00e7\u00f5es<\/a><\/noindex> sobre o ataque KNOB<\/a><\/noindex> (Key Negotiation Of Bluetooth), permitindo a intercepta\u00e7\u00e3o e substitui\u00e7\u00e3o de informa\u00e7\u00f5es no tr\u00e1fego Bluetooth criptografado. Com a capacidade de bloquear a transmiss\u00e3o direta de pacotes durante o processo de negocia\u00e7\u00e3o de conex\u00e3o entre dispositivos Bluetooth, o atacante pode for\u00e7ar a utiliza\u00e7\u00e3o de chaves com apenas 1 byte de entropia para a sess\u00e3o, possibilitando a aplica\u00e7\u00e3o do m\u00e9todo de for\u00e7a bruta para determinar a chave de criptografia. <\/p>\n

O problema \u00e9 causado por falhas (CVE-2019-9506) na especifica\u00e7\u00e3o Bluetooth BR\/EDR Core 5.1 e vers\u00f5es anteriores, que permitem o uso de chaves de criptografia muito curtas e n\u00e3o impedem a interfer\u00eancia do atacante durante a fase de negocia\u00e7\u00e3o de conex\u00e3o, permitindo a reodnica\u00e7\u00e3o para chaves inseguras semelhantes (substitui\u00e7\u00e3o de pacotes por um atacante n\u00e3o autenticado \u00e9 poss\u00edvel). O ataque pode ser realizado durante a negocia\u00e7\u00e3o de conex\u00e3o dos dispositivos (sess\u00f5es j\u00e1 estabelecidas n\u00e3o podem ser atacadas) e \u00e9 eficaz apenas para conex\u00f5es nos modos BR\/EDR (Bluetooth Basic Rate\/Enhanced Data Rate), se ambos os dispositivos forem vulner\u00e1veis. Em caso de sucesso na quebra da chave, o invasor pode decifrar dados transmitidos e executar a substitui\u00e7\u00e3o no tr\u00e1fego de texto cifrado sem que a v\u00edtima perceba.<\/p>\n

Ao estabelecer uma conex\u00e3o entre dois controladores Bluetooth A e B, o controlador A, ap\u00f3s a autentica\u00e7\u00e3o por meio da chave de link (link key), pode sugerir o uso de uma chave de criptografia (encryption key) de 16 bytes de entropia, e o controlador B pode aceitar esse valor ou indicar um valor menor, caso n\u00e3o consiga formar uma chave do tamanho proposto. Em resposta, o controlador A pode aceitar a proposta e ativar o canal de comunica\u00e7\u00e3o criptografado. Neste est\u00e1gio da negocia\u00e7\u00e3o, a criptografia n\u00e3o \u00e9 aplicada, portanto o atacante tem a oportunidade de interferir na troca de dados entre os controladores e substituir o pacote com o tamanho de entropia proposto. Como o tamanho aceit\u00e1vel da chave varia de 1 a 16 bytes, o segundo controlador aceitar\u00e1 esse valor e enviar\u00e1 sua confirma\u00e7\u00e3o com um tamanho equivalente.<\/p>\n

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

Para reproduzir a vulnerabilidade em condi\u00e7\u00f5es de laborat\u00f3rio (a atividade do invasor foi emulada em um dos dispositivos), foi proposto
\num prot\u00f3tipo de ferramenta<\/a><\/noindex> para realizar um ataque.
\nPara um ataque real, o atacante deve estar na faixa de recep\u00e7\u00e3o dos dispositivos-alvo e ser capaz de bloquear temporariamente o sinal de cada dispositivo, o que pode ser implementado atrav\u00e9s da manipula\u00e7\u00e3o do sinal ou da interfer\u00eancia reativa. <\/p>\n

A organiza\u00e7\u00e3o Bluetooth SIG, respons\u00e1vel pelo desenvolvimento dos padr\u00f5es Bluetooth, publicou<\/a><\/noindex> realizou a corre\u00e7\u00e3o da especifica\u00e7\u00e3o n\u00famero 11838, na qual foram propostas medidas para os fabricantes bloquearem a vulnerabilidade (o tamanho m\u00ednimo da chave de criptografia foi aumentado de 1 para 7). O problema se manifesta<\/a><\/noindex> em todas<\/a><\/noindex> as pilhas Bluetooth e firmwares Bluetooth que atendem ao padr\u00e3o, incluindo produtos Intel<\/a><\/noindex>, Broadcom, Lenovo<\/a><\/noindex>, Apple<\/a><\/noindex>, Microsoft<\/a><\/noindex>, Qualcomm, Linux, Android<\/a><\/noindex>, Blackberry<\/a><\/noindex> e Cisco<\/a><\/noindex> (de 14 chips testados, todos se mostraram vulner\u00e1veis). No stack Bluetooth do kernel Linux foi inserido<\/a><\/noindex> uma corre\u00e7\u00e3o que permite alterar o tamanho m\u00ednimo da chave de criptografia. <\/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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