{"id":35396,"date":"2019-10-31T22:04:04","date_gmt":"2019-10-31T19:04:04","guid":{"rendered":"https:\/\/prohoster.info\/blog\/uyazvimosti-v-tcp-stekah-linux-i-freebsd-privodyashhie-k-udalyonnomu-otkazu-v-obsluzhivanii\/"},"modified":"2019-10-31T22:04:04","modified_gmt":"2019-10-31T19:04:04","slug":"uyazvimosti-v-tcp-stekah-linux-i-freebsd-privodyashhie-k-udalyonnomu-otkazu-v-obsluzhivanii","status":"publish","type":"post","link":"https:\/\/prohoster.info\/pt\/blog\/news\/uyazvimosti-v-tcp-stekah-linux-i-freebsd-privodyashhie-k-udalyonnomu-otkazu-v-obsluzhivanii","title":{"rendered":"Vulnerabilidades nas pilhas TCP do Linux e FreeBSD que levam \u00e0 nega\u00e7\u00e3o de servi\u00e7o remoto","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Empresa Netflix expose<\/a><\/noindex> v\u00e1rios problemas cr\u00edticos vulnerabilidades<\/a><\/noindex> nos stacks TCP do Linux e FreeBSD, que permitem iniciar remotamente uma falha do kernel ou causar consumo excessivo de recursos ao processar pacotes TCP formatados de forma especial (packet-of-death). Os problemas s\u00e3o causados<\/a><\/noindex> por falhas nos manipuladores do tamanho m\u00e1ximo do bloco de dados no pacote TCP (MSS, Maximum Segment Size) e no mecanismo de confirma\u00e7\u00e3o seletiva de conex\u00f5es (SACK, TCP Selective Acknowledgement).<\/p>\n

  • CVE-2019-11477<\/a><\/noindex> (SACK Panic) \u2014 o problema se manifesta em n\u00facleos Linux a partir da vers\u00e3o 2.6.29 e permite causar uma falha (panic) do kernel ao enviar uma s\u00e9rie de pacotes SACK devido a um overflow de inteiro no manipulador. Para realizar o ataque, basta definir o valor MSS para a conex\u00e3o TCP em 48 bytes (o limite inferior, que estabelece o tamanho do segmento em 8 bytes) e enviar uma sequ\u00eancia de pacotes SACK organizados de maneira espec\u00edfica.\n

    Como medidas alternativas de prote\u00e7\u00e3o, \u00e9 poss\u00edvel desativar o processamento de SACK (definindo 0 em \/proc\/sys\/net\/ipv4\/tcp_sack) ou bloquear<\/a><\/noindex> conex\u00f5es com baixo MSS (funciona apenas quando o sysctl net.ipv4.tcp_mtu_probing \u00e9 definido como 0 e pode interferir no funcionamento de algumas conex\u00f5es normais com baixo MSS);<\/p>\n

  • CVE-2019-11478<\/a><\/noindex> (SACK Slowness) \u2014 causa uma interrup\u00e7\u00e3o no funcionamento do mecanismo SACK (quando usando um n\u00facleo Linux anterior \u00e0 vers\u00e3o 4.15) ou um consumo excessivo de recursos. O problema se manifesta ao processar pacotes SACK especialmente formatados, que podem ser usados para fragmentar a fila de retransmiss\u00e3o TCP. As medidas de mitiga\u00e7\u00e3o s\u00e3o similares \u00e0s da vulnerabilidade anterior;\n
  • CVE-2019-5599<\/a><\/noindex> (SACK Slowness) \u2014 permite a fragmenta\u00e7\u00e3o do mapa de pacotes enviados ao processar uma sequ\u00eancia especial de SACK dentro de uma \u00fanica conex\u00e3o TCP e pode resultar na execu\u00e7\u00e3o de uma opera\u00e7\u00e3o intensiva em recursos para percorrer a lista. O problema se manifesta no FreeBSD 12 com o mecanismo de detec\u00e7\u00e3o de perda de pacotes RACK. Como uma medida, o m\u00f3dulo RACK pode ser desativado;\n
  • CVE-2019-11479<\/a><\/noindex> \u2014 um atacante pode provocar a separa\u00e7\u00e3o das respostas no n\u00facleo Linux em v\u00e1rios segmentos TCP, cada um contendo apenas 8 bytes de dados, o que pode resultar em um aumento significativo de tr\u00e1fego, sobrecarga do CPU e congestionamento do link. Como m\u00e9todo de prote\u00e7\u00e3o, recomenda-se bloquear<\/a><\/noindex> conex\u00f5es com baixo MSS.\n<\/ul>\n

    No kernel Linux, os problemas foram corrigidos nas vers\u00f5es 4.4.182, 4.9.182, 4.14.127, 4.19.52 e 5.1.11. A corre\u00e7\u00e3o para o FreeBSD est\u00e1 dispon\u00edvel na forma de patch<\/a><\/noindex>. Atualiza\u00e7\u00f5es de pacotes com o kernel j\u00e1 foram lan\u00e7adas para Debian<\/a><\/noindex>, RHEL<\/a><\/noindex>, SUSE\/openSUSE<\/a><\/noindex>. Corre\u00e7\u00e3o em prepara\u00e7\u00e3o em Ubuntu<\/a><\/noindex>, Fedora<\/a><\/noindex> e EPEL para RHEL\/CentOS<\/a><\/noindex>.<\/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 Netflix \u0432\u044b\u044f\u0432\u0438\u043b\u0430 \u043d\u0435\u0441\u043a\u043e\u043b\u044c\u043a\u043e \u043a\u0440\u0438\u0442\u0438\u0447\u0435\u0441\u043a\u0438\u0445 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0435\u0439 \u0432 TCP-\u0441\u0442\u0435\u043a\u0430\u0445 Linux \u0438 FreeBSD, \u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0442 \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e \u0438\u043d\u0438\u0446\u0438\u0438\u0440\u043e\u0432\u0430\u0442\u044c \u043a\u0440\u0430\u0445 \u044f\u0434\u0440\u0430 \u0438\u043b\u0438 \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u0447\u0440\u0435\u0437\u043c\u0435\u0440\u043d\u043e\u0435 \u043f\u043e\u0442\u0440\u0435\u0431\u043b\u0435\u043d\u0438\u0435 \u0440\u0435\u0441\u0443\u0440\u0441\u043e\u0432 \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u0445 TCP-\u043f\u0430\u043a\u0435\u0442\u043e\u0432 (packet-of-death). \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u0432\u044b\u0437\u0432\u0430\u043d\u044b \u043e\u0448\u0438\u0431\u043a\u0430\u043c\u0438 \u0432 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u0447\u0438\u043a\u0430\u0445 \u043c\u0430\u043a\u0441\u0438\u043c\u0430\u043b\u044c\u043d\u043e\u0433\u043e \u0440\u0430\u0437\u043c\u0435\u0440\u0430 \u0431\u043b\u043e\u043a\u0430 \u0434\u0430\u043d\u043d\u044b\u0445 \u0432 TCP-\u043f\u0430\u043a\u0435\u0442\u0435 (MSS, Maximum segment size) \u0438 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u0430 \u0432\u044b\u0431\u043e\u0440\u043e\u0447\u043d\u043e\u0433\u043e \u043f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u0438\u044f \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u0439 (SACK, TCP Selective Acknowledgement). CVE-2019-11477 (SACK Panic) […]<\/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-35396","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\udd47Vulnerabilidades nas pilhas TCP do Linux e FreeBSD, que podem levar a uma nega\u00e7\u00e3o de servi\u00e7o remota | ProHoster","description":"A empresa Netflix identificou v\u00e1rias vulnerabilidades cr\u00edticas","canonical_url":"https:\/\/prohoster.info\/pt\/blog\/news\/uyazvimosti-v-tcp-stekah-linux-i-freebsd-privodyashhie-k-udalyonnomu-otkazu-v-obsluzhivanii","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"pt_PT","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 TCP-\u0441\u0442\u0435\u043a\u0430\u0445 Linux \u0438 FreeBSD, \u043f\u0440\u0438\u0432\u043e\u0434\u044f\u0449\u0438\u0435 \u043a \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e\u043c\u0443 \u043e\u0442\u043a\u0430\u0437\u0443 \u0432 \u043e\u0431\u0441\u043b\u0443\u0436\u0438\u0432\u0430\u043d\u0438\u0438 | ProHoster","og:description":"\u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Netflix \u0432\u044b\u044f\u0432\u0438\u043b\u0430 \u043d\u0435\u0441\u043a\u043e\u043b\u044c\u043a\u043e \u043a\u0440\u0438\u0442\u0438\u0447\u0435\u0441\u043a\u0438\u0445","og:url":"https:\/\/prohoster.info\/pt\/blog\/news\/uyazvimosti-v-tcp-stekah-linux-i-freebsd-privodyashhie-k-udalyonnomu-otkazu-v-obsluzhivanii","og:image":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:secure_url":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:width":350,"og:image:height":350,"article:published_time":"2019-10-31T19:04:04+00:00","article:modified_time":"2019-10-31T19:04:04+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster","article:author":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":{"post_id":"35396","title":null,"description":null,"keywords":null,"keyphrases":null,"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":null,"schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"seo_analyzer_scan_date":"2026-01-21 23:03:19","breadcrumb_settings":null,"limit_modified_date":false,"reviewed_by":null,"ai":null,"created":"2021-02-28 17:03:04","updated":"2026-01-21 23:03:19","focus_keyword":null,"additional_keywords":null,"truseo_locale":null},"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/posts\/35396","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/comments?post=35396"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/posts\/35396\/revisions"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/media?parent=35396"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/categories?post=35396"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/pt\/wp-json\/wp\/v2\/tags?post=35396"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}