{"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\/es\/blog\/news\/kriticheskaya-uyazvimost-v-realizaczii-funkczii-memcpy-dlya-armv7-iz-sostava-glibc","title":{"rendered":"Vulnerabilidad cr\u00edtica en la implementaci\u00f3n de la funci\u00f3n memcpy para ARMv7 del conjunto de Glibc","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Investigadores de seguridad de Cisco revelaron<\/a><\/noindex> detalles una vulnerabilidad<\/a><\/noindex> (CVE-2020-6096<\/a><\/noindex>) en la implementaci\u00f3n de la funci\u00f3n memcpy() proporcionada en Glibc para plataformas ARMv7 de 32 bits. El problema se debe a un manejo incorrecto de valores negativos en el par\u00e1metro que define el tama\u00f1o del \u00e1rea copiada, debido al uso de optimizaciones en ensamblador que manipulan enteros de 32 bits con signo. Llamar a memcpy() en sistemas ARMv7 con un tama\u00f1o negativo provoca comparaciones de valores incorrectas y escrituras en \u00e1reas fuera de los l\u00edmites del b\u00fafer especificado.<\/p>\n

La vulnerabilidad puede ser explotada para ejecutar c\u00f3digo en situaciones en las que un atacante puede manipular la generaci\u00f3n de un valor negativo para la variable que transmite el tama\u00f1o de los datos copiados (por ejemplo, se producir\u00e1 un valor negativo al transmitir m\u00e1s de 2 GB de datos, pero durante el ataque es necesario transmitir al menos 4 GB para desbordar el b\u00fafer). La funci\u00f3n memcpy() se utiliza ampliamente en aplicaciones, y los procesadores ARMv7 est\u00e1n presentes en sistemas automotrices, dispositivos m\u00f3viles, industriales, de consumo, de comunicaci\u00f3n y embebidos, que potencialmente pueden ser objeto de ataques utilizando Bluetooth, HD Radio\/DAB, USB, CAN bus, Wi-Fi y otras fuentes externas de datos (por ejemplo, servicios y aplicaciones accesibles en red que aceptan entradas sin restricciones de tama\u00f1o).<\/p>\n

Como ejemplo, se presenta la creaci\u00f3n de un exploit funcional para atacar al servidor http incorporado en los sistemas de infoentretenimiento del autom\u00f3vil, accesible a trav\u00e9s de la red Wi-Fi del veh\u00edculo. Un atacante externo puede explotar la vulnerabilidad en memcpy en este servidor al enviar una solicitud GET de tama\u00f1o muy grande y obtener acceso root al sistema.<\/p>\n

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

En sistemas x86 de 32 bits, el problema no se manifiesta, ya que la implementaci\u00f3n de memcpy para esta arquitectura interpreta correctamente la variable de tama\u00f1o como un valor entero sin signo del tipo size_t (en el ensamblador, implementaci\u00f3n<\/a><\/noindex> para ARMv7 se maneja como un entero con signo). La correcci\u00f3n est\u00e1 disponible por ahora como parche<\/a><\/noindex>, que formar\u00e1 parte de la actualizaci\u00f3n de agosto de Glibc 2.32.
\nLa correcci\u00f3n consiste en reemplazar el uso de instrucciones de ensamblador que operan con operandos con signo (bge y blt) por an\u00e1logos sin signo (blo y bhs). <\/p>\n

El problema a\u00fan no se ha solucionado en Debian 9 y 10<\/a><\/noindex> (no se manifiesta en Debian 8). Fedora<\/a><\/noindex>, Ubuntu<\/a><\/noindex>, OpenEmbedded, Tizen (utiliza glibc). RHEL<\/a><\/noindex> y SUSE<\/a><\/noindex> el problema no afecta, ya que no soportan sistemas ARMv7 de 32 bits. Android no es vulnerable, ya que utiliza su propia implementaci\u00f3n de libc (Bionic). En OpenWRT<\/a><\/noindex> la mayor\u00eda de las compilaciones usa Musl por defecto, pero en el repositorio tambi\u00e9n se encuentra glibc.<\/p>\n

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

Fuente: 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\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\udd47Vulnerabilidad cr\u00edtica en la implementaci\u00f3n de la funci\u00f3n memcpy para ARMv7 en glibc | ProHoster","description":"Los investigadores de seguridad de Cisco revelaron 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