{"id":101115,"date":"2021-08-28T10:22:53","date_gmt":"2021-08-28T08:22:53","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-libssh-privodyashhaya-k-perepolneniyu-bufera"},"modified":"2021-08-28T10:22:53","modified_gmt":"2021-08-28T08:22:53","slug":"uyazvimost-v-libssh-privodyashhaya-k-perepolneniyu-bufera","status":"publish","type":"post","link":"https:\/\/prohoster.info\/de\/blog\/news\/uyazvimost-v-libssh-privodyashhaya-k-perepolneniyu-bufera","title":{"rendered":"Sicherheitsanf\u00e4lligkeit in libssh, die zu einem Puffer\u00fcberlauf f\u00fchrt","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

In der Bibliothek libssh (nicht zu verwechseln mit libssh2), die zur Implementierung der Client- und Serverunterst\u00fctzung des SSHv2-Protokolls in C-Programmen dient, wurde eine Schwachstelle (CVE-2021-3634) entdeckt, die zu einem Puffer\u00fcberlauf f\u00fchren kann, wenn der Prozess zur Schl\u00fcsselwechsel (rekey) unter Verwendung eines Schl\u00fcssel\u00fcbertragungsmechanismus initiiert wird, der einen anderen Hashalgorithmus anwendet. Das Problem wurde in der Version 0.9.6 behoben. <\/p>\n

Das Problem liegt darin, dass der Schl\u00fcsselwechsel kryptografische Hashes mit einer Abmessung erm\u00f6glicht, die sich von dem urspr\u00fcnglich verwendeten Algorithmus unterscheidet. Dabei wurde der Speicher f\u00fcr den Hash in libssh basierend auf der urspr\u00fcnglichen Hash-Gr\u00f6\u00dfe zugewiesen, und die Verwendung eines gr\u00f6\u00dferen Hashes f\u00fchrt dazu, dass Daten au\u00dferhalb des zugewiesenen Puffers \u00fcberschrieben werden. Als Backup-Schutzmethode k\u00f6nnte man die Liste der unterst\u00fctzten Schl\u00fcsselwechselverfahren auf Algorithmen mit identischer Hash-Gr\u00f6\u00dfe beschr\u00e4nken. Zum Beispiel k\u00f6nnte man zur Bindung an SHA256 im Code hinzuf\u00fcgen: rc = ssh_options_set(s->ssh.session, SSH_OPTIONS_KEY_EXCHANGE, \"diffie-hellman-group14-sha256,curve25519-sha256,ecdh-sha2-nistp256\");
\n
Quelle: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0435 libssh (\u043d\u0435 \u043f\u0443\u0442\u0430\u0442\u044c \u0441 libssh2), \u043f\u0440\u0435\u0434\u043d\u0430\u0437\u043d\u0430\u0447\u0435\u043d\u043d\u043e\u0439 \u0434\u043b\u044f \u0434\u043e\u0431\u0430\u0432\u043b\u0435\u043d\u0438\u044f \u043a\u043b\u0438\u0435\u043d\u0442\u0441\u043a\u043e\u0439 \u0438 \u0441\u0435\u0440\u0432\u0435\u0440\u043d\u043e\u0439 \u043f\u043e\u0434\u0434\u0435\u0440\u0436\u043a\u0438 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0430 SSHv2 \u0432 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u044b \u043d\u0430 \u044f\u0437\u044b\u043a\u0435 \u0421\u0438, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2021-3634), \u043f\u0440\u0438\u0432\u043e\u0434\u044f\u0449\u0430\u044f \u043a \u043f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044e \u0431\u0443\u0444\u0435\u0440\u0430 \u043f\u0440\u0438 \u0438\u043d\u0438\u0446\u0438\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0438 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u0430 \u0441\u043c\u0435\u043d\u044b \u043a\u043b\u044e\u0447\u0430 (rekey) \u0441 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435\u043c \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u0430 \u043e\u0431\u043c\u0435\u043d\u0430 \u043a\u043b\u044e\u0447\u0430\u043c\u0438, \u043f\u0440\u0438\u043c\u0435\u043d\u044f\u044e\u0449\u0435\u0433\u043e \u0434\u0440\u0443\u0433\u043e\u0439 \u0430\u043b\u0433\u043e\u0440\u0438\u0442\u043c \u0445\u044d\u0448\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430 \u0432 \u0432\u044b\u043f\u0443\u0441\u043a\u0435 0.9.6. \u0421\u0443\u0442\u044c \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u0432 \u0442\u043e\u043c, \u0447\u0442\u043e \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u044f \u0441\u043c\u0435\u043d\u044b […]<\/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-101115","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\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\udd47Schwachstelle in libssh, die zu einem Puffer\u00fcberlauf f\u00fchrt | ProHoster","description":"In der Bibliothek libssh (nicht zu verwechseln mit libssh2), die zur Implementierung der Client- und Serverunterst\u00fctzung des SSHv2-Protokolls in C-Programmen dient, wurde eine Schwachstelle (CVE-2021-3634) entdeckt, die zu einem \u00dcberlauf 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(\u043d\u0435 \u043f\u0443\u0442\u0430\u0442\u044c \u0441 libssh2), \u043f\u0440\u0435\u0434\u043d\u0430\u0437\u043d\u0430\u0447\u0435\u043d\u043d\u043e\u0439 \u0434\u043b\u044f \u0434\u043e\u0431\u0430\u0432\u043b\u0435\u043d\u0438\u044f \u043a\u043b\u0438\u0435\u043d\u0442\u0441\u043a\u043e\u0439 \u0438 \u0441\u0435\u0440\u0432\u0435\u0440\u043d\u043e\u0439 \u043f\u043e\u0434\u0434\u0435\u0440\u0436\u043a\u0438 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0430 SSHv2 \u0432 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u044b \u043d\u0430 \u044f\u0437\u044b\u043a\u0435 \u0421\u0438, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2021-3634), \u043f\u0440\u0438\u0432\u043e\u0434\u044f\u0449\u0430\u044f \u043a 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