{"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\/nl\/blog\/news\/uyazvimosti-v-tcp-stekah-linux-i-freebsd-privodyashhie-k-udalyonnomu-otkazu-v-obsluzhivanii","title":{"rendered":"Kwetsbaarheden in de TCP-stacks van Linux en FreeBSD, die leiden tot een remote denial-of-service.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Het bedrijf Netflix heeft<\/a><\/noindex> meerdere kritieke kwetsbaarheden<\/a><\/noindex> in de TCP-stacks van Linux en FreeBSD, die het mogelijk maken om op afstand een kernelcrash te initi\u00ebren of excessive resource consumption te veroorzaken bij de verwerking van speciaal geprepareerde TCP-pakketten (packet-of-death). De problemen worden veroorzaakt door<\/a><\/noindex> fouten in de verwerkingsmechanismen voor de Maximum Segment Size (MSS) en het Selective Acknowledgement (SACK) mechanisme.<\/p>\n

  • CVE-2019-11477<\/a><\/noindex> (SACK Panic) \u2014 het probleem doet zich voor in de Linux-kernel vanaf versie 2.6.29 en stelt een aanvaller in staat om een kernel panic te veroorzaken door een reeks SACK-pakketten te verzenden als gevolg van een integer overflow in de handler. Voor de aanval is het voldoende om de MSS-waarde voor de TCP-verbinding in te stellen op 48 bytes (de ondergrens, die de segmentgrootte op 8 bytes instelt) en een specifieke volgorde van SACK-pakketten te verzenden.\n

    Als tijdelijke oplossingen voor bescherming kunt u SACK-verwerking uitschakelen (stel 0 in op \/proc\/sys\/net\/ipv4\/tcp_sack) of verbinden<\/a><\/noindex> met lage MSS blokkeren (werkt alleen als sysctl net.ipv4.tcp_mtu_probing op 0 is ingesteld en kan de werking van sommige normale verbindingen met lage MSS verstoren);<\/p>\n

  • CVE-2019-11478<\/a><\/noindex> (SACK Slowness) \u2014 leidt tot storingen in de werking van het SACK-mechanisme (bij gebruik van Linux-kernelversies ouder dan 4.15) of tot overmatig gebruik van middelen. Het probleem doet zich voor bij de verwerking van speciaal opgemaakte SACK-pakketten, die kunnen worden gebruikt om de retransmissiequeue (TCP retransmission) te fragmenteren. De workaround voor bescherming is vergelijkbaar met de vorige kwetsbaarheid;\n
  • CVE-2019-5599<\/a><\/noindex> (SACK Slowness) \u2014 stelt een aanvaller in staat om de fragmentatie van de verzonden pakkettenkaart te veroorzaken bij de verwerking van een speciale SACK-volgorde binnen dezelfde TCP-verbinding en het uitvoeren van een resource-intensieve lijstdoorzoekoperatie. Het probleem doet zich voor in FreeBSD 12 met het RACK-pakketverliezenmechanisme. Als workaround kan de RACK-module worden uitgeschakeld;\n
  • CVE-2019-11479<\/a><\/noindex> \u2014 de aanvaller kan in de Linux-kernel een splitsing van antwoorden in verschillende TCP-segmenten forceren, waarbij elk segment slechts 8 bytes aan gegevens bevat, wat kan leiden tot een aanzienlijke toename van het verkeer, verhoogde CPU-belasting en congestie van de communicatieverbinding. Als beschermingsmethode wordt aangeraden verbinden<\/a><\/noindex> verbindingen met lage MSS.\n<\/ul>\n

    In de Linux-kern zijn er problemen verholpen in de versies 4.4.182, 4.9.182, 4.14.127, 4.19.52 en 5.1.11. De oplossing voor FreeBSD is beschikbaar als patch<\/a><\/noindex>. In de distributies zijn pakketupdates met de kern al uitgebracht voor Debian<\/a><\/noindex>, RHEL<\/a><\/noindex>, SUSE\/openSUSE<\/a><\/noindex>. De oplossing is in voorbereiding in Ubuntu<\/a><\/noindex>, Fedora<\/a><\/noindex> en Arch Linux<\/a><\/noindex>.<\/p>\n

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

    Bron: 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\udd47Kwetsbaarheden in de TCP-stacks van Linux en FreeBSD, leidend tot een remote denial of service | ProHoster","description":"Het bedrijf Netflix heeft verschillende kritieke","canonical_url":"https:\/\/prohoster.info\/nl\/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":"nl_NL","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 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