{"id":112308,"date":"2023-12-19T03:10:22","date_gmt":"2023-12-19T01:10:22","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/terrapin-uyazvimost-v-protokole-ssh-pozvolyayushhaya-snizit-zashhitu-soedineniya"},"modified":"2023-12-19T03:10:22","modified_gmt":"2023-12-19T01:10:22","slug":"terrapin-uyazvimost-v-protokole-ssh-pozvolyayushhaya-snizit-zashhitu-soedineniya","status":"publish","type":"post","link":"https:\/\/prohoster.info\/it\/blog\/news\/terrapin-uyazvimost-v-protokole-ssh-pozvolyayushhaya-snizit-zashhitu-soedineniya","title":{"rendered":"Terrapin &#8212; vulnerabilit\u00e0 nel protocollo SSH che consente di ridurre la protezione della connessione","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Un gruppo di ricercatori dell'Universit\u00e0 di Bochum (Germania) ha presentato una nuova tecnica di attacco MITM su SSH - Terrapin, che sfrutta una vulnerabilit\u00e0 (CVE-2023-48795) nel protocollo. L'attaccante, in grado di organizzare un attacco MITM, ha la possibilit\u00e0, durante la negoziazione della connessione, di bloccare l'invio del messaggio contenente la configurazione delle estensioni del protocollo per ridurre il livello di protezione della connessione. Un prototipo dello strumento per effettuare l'attacco \u00e8 stato pubblicato su GitHub.    <\/p>\n<p>Nel contesto di OpenSSH, la vulnerabilit\u00e0 consente, ad esempio, di ripristinare la connessione a utilizzo di algoritmi di autenticazione meno sicuri e disattivare la protezione contro attacchi di canali laterali, cos\u00ec da ricreare l'input tramite l'analisi dei ritardi fra la pressione dei tasti sulla tastiera. Nella libreria Python AsyncSSH, insieme alla vulnerabilit\u00e0 (CVE-2023-46446) nell'implementazione della macchina a stati interni, l'attacco Terrapin consente di infiltrarsi in una sessione SSH.      <\/p>\n<p>La vulnerabilit\u00e0 interessa tutte le implementazioni di SSH che supportano ChaCha20-Poly1305 o cifrature in modalit\u00e0 CBC in combinazione con la modalit\u00e0 ETM (Encrypt-then-MAC). Ad esempio, tali possibilit\u00e0 sono presenti in OpenSSH da oltre 10 anni. La vulnerabilit\u00e0 \u00e8 stata bloccata nell'attuale versione di OpenSSH 9.6 e nelle aggiornamenti di PuTTY 0.80, libssh 0.10.6\/0.9.8 e AsyncSSH 2.14.2. In Dropbear SSH la correzione \u00e8 gi\u00e0 stata aggiunta al codice, ma una nuova versione non \u00e8 ancora stata rilasciata.      <\/p>\n<p>La vulnerabilit\u00e0 \u00e8 causata dal fatto che un attaccante, che controlla il traffico della connessione (ad esempio, il proprietario di un hotspot wireless malevolo), pu\u00f2 modificare i numeri di sequenza dei pacchetti durante la negoziazione della connessione e ottenere la rimozione invisibile di un numero arbitrario di messaggi di servizio SSH inviati dal client o <a class=\"wpil_keyword_link\" href=\"https:\/\/prohoster.info\/it\/server\/dts-prohoster\/\"   title=\"server\" data-wpil-keyword-link=\"linked\"  data-wpil-monitor-id=\"3020\">server<\/a>. Tra l'altro, l'attaccante pu\u00f2 rimuovere i messaggi SSH_MSG_EXT_INFO, utilizzati per configurare le estensioni del protocollo applicate. Affinch\u00e9 l'altra parte non rilevi la mancanza di un pacchetto a causa della rottura nei numeri di sequenza, l'attaccante avvia l'invio di un pacchetto fittizio con lo stesso numero di sequenza di quello rimosso. Il pacchetto fittizio contiene un messaggio con il flag SSH_MSG_IGNORE, che viene ignorato durante l'elaborazione.     <center><img decoding=\"async\" alt=\"Terrapin - vulnerabilit\u00e0 nel protocollo SSH che consente di ridurre la protezione della connessione.\" src=\"\/wp-content\/uploads\/2023\/12\/8e3dad7329f9c01cbef81b7029aabdee.png\" style=\"display:block;margin: 0 auto;\" \/><\/center>      <\/p>\n<p>L'attacco non pu\u00f2 essere eseguito utilizzando cifrari a flusso e CTR, poich\u00e9 la violazione dell'integrit\u00e0 verr\u00e0 rilevata a livello di applicazione. In pratica, \u00e8 solo il cifrario ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) ad essere vulnerabile, poich\u00e9 lo stato \u00e8 monitorato solo tramite i numeri di sequenza dei messaggi, e la combinazione della modalit\u00e0 Encrypt-Then-MAC (*-etm@openssh.com) e dei cifrari CBC.      <\/p>\n<p>In OpenSSH 9.6 e in altre implementazioni, per bloccare l'attacco \u00e8 stata implementata un'estensione del protocollo \u00abstrict KEX\u00bb, che si attiva automaticamente se supportata dal lato. <a class=\"wpil_keyword_link\" href=\"https:\/\/prohoster.info\/it\/server\/dts-los-angeles\/\"   title=\"server\" data-wpil-keyword-link=\"linked\"  data-wpil-monitor-id=\"3752\">server<\/a> client. Questa estensione termina la connessione quando vengono ricevuti messaggi non standard o indesiderati (ad esempio, con il flag SSH_MSG_IGNORE o SSH2_MSG_DEBUG) durante il processo di negoziazione della connessione e reimposta il contatore MAC (Message Authentication Code) dopo ogni scambio di chiavi.<br \/>\n<br \/>Fonte: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=60304\">opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0413\u0440\u0443\u043f\u043f\u0430 \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u0439 \u0438\u0437 \u0420\u0443\u0440\u0441\u043a\u043e\u0433\u043e \u0443\u043d\u0438\u0432\u0435\u0440\u0441\u0438\u0442\u0435\u0442\u0430 \u0432 \u0411\u043e\u0445\u0443\u043c\u0435 (\u0413\u0435\u0440\u043c\u0430\u043d\u0438\u044f) \u043f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u0438\u043b\u0430 \u043d\u043e\u0432\u0443\u044e \u0442\u0435\u0445\u043d\u0438\u043a\u0443 MITM-\u0430\u0442\u0430\u043a\u0438 \u043d\u0430 SSH &#8212; Terrapin, \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0438\u0440\u0443\u044e\u0449\u0443\u044e \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2023-48795) \u0432 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0435. \u0410\u0442\u0430\u043a\u0443\u044e\u0449\u0438\u0439, \u0441\u043f\u043e\u0441\u043e\u0431\u043d\u044b\u0439 \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u043e\u0432\u0430\u0442\u044c MITM-\u0430\u0442\u0430\u043a\u0443, \u0438\u043c\u0435\u0435\u0442 \u0432\u043e\u0437\u043c\u043e\u0436\u043d\u043e\u0441\u0442\u044c \u0432 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u0435 \u0441\u043e\u0433\u043b\u0430\u0441\u043e\u0432\u0430\u043d\u0438\u044f \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u044f \u0431\u043b\u043e\u043a\u0438\u0440\u043e\u0432\u0430\u0442\u044c \u043e\u0442\u043f\u0440\u0430\u0432\u043a\u0443 \u0441\u043e\u043e\u0431\u0449\u0435\u043d\u0438\u044f \u0441 \u043d\u0430\u0441\u0442\u0440\u043e\u0439\u043a\u043e\u0439 \u0440\u0430\u0441\u0448\u0438\u0440\u0435\u043d\u0438\u0439 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0430 \u0434\u043b\u044f \u0441\u043d\u0438\u0436\u0435\u043d\u0438\u044f \u0443\u0440\u043e\u0432\u043d\u044f \u0437\u0430\u0449\u0438\u0442\u044b \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u044f. \u041f\u0440\u043e\u0442\u043e\u0442\u0438\u043f \u0438\u043d\u0441\u0442\u0440\u0443\u043c\u0435\u043d\u0442\u0430\u0440\u0438\u044f \u0434\u043b\u044f \u0441\u043e\u0432\u0435\u0440\u0448\u0435\u043d\u0438\u044f \u0430\u0442\u0430\u043a\u0438 \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d \u043d\u0430 GitHub. \u0412 \u043a\u043e\u043d\u0442\u0435\u043a\u0441\u0442\u0435 OpenSSH \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, [&hellip;]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":112309,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-112308","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.1.1 - 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Terrapin, che sfrutta la vulnerabilit\u00e0 (CVE-2023-48795) nel protocollo.","canonical_url":"https:\/\/prohoster.info\/it\/blog\/news\/terrapin-uyazvimost-v-protokole-ssh-pozvolyayushhaya-snizit-zashhitu-soedineniya","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"it_IT","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\udd47Terrapin \u2014 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0435 SSH, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0441\u043d\u0438\u0437\u0438\u0442\u044c \u0437\u0430\u0449\u0438\u0442\u0443 \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u044f | ProHoster","og:description":"\u0413\u0440\u0443\u043f\u043f\u0430 \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u0439 \u0438\u0437 \u0420\u0443\u0440\u0441\u043a\u043e\u0433\u043e \u0443\u043d\u0438\u0432\u0435\u0440\u0441\u0438\u0442\u0435\u0442\u0430 \u0432 \u0411\u043e\u0445\u0443\u043c\u0435 (\u0413\u0435\u0440\u043c\u0430\u043d\u0438\u044f) \u043f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u0438\u043b\u0430 \u043d\u043e\u0432\u0443\u044e \u0442\u0435\u0445\u043d\u0438\u043a\u0443 MITM-\u0430\u0442\u0430\u043a\u0438 \u043d\u0430 SSH - 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