{"id":92097,"date":"2020-08-22T19:42:16","date_gmt":"2020-08-22T17:42:16","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-chrony"},"modified":"2020-08-22T19:42:16","modified_gmt":"2020-08-22T17:42:16","slug":"uyazvimost-v-chrony","status":"publish","type":"post","link":"https:\/\/prohoster.info\/en\/blog\/news\/uyazvimost-v-chrony","title":{"rendered":"Vulnerability in chrony","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

In chrony<\/a><\/noindex>, implementation of the NTP protocol used for synchronizing accurate time across various Linux distributions, identified<\/a><\/noindex> vulnerability (CVE-2020-14367<\/a><\/noindex>), allowing to overwrite any file in the system by having access as a local unprivileged user chrony. The vulnerability can only be exploited through the chrony user, which reduces its danger. However, the issue compromises the isolation level in chrony and could be used if another vulnerability in the code executed after privilege reset is discovered.<\/p>\n

The vulnerability is caused by the unsafe creation of the pid file, which was created at a stage when chrony had not yet dropped privileges and is running with root rights. The directory \/run\/chrony, where the pid file is written, was created with permissions 0750 through systemd-tmpfiles or when starting chronyd tied to the user and group 'chrony'. Therefore, if access to the chrony user is available, there is an opportunity to replace the pid file \/run\/chrony\/chronyd.pid with a symbolic link. The symbolic link can point to any system file that will be overwritten at the moment chronyd starts.<\/p>\n

root# systemctl stop chronyd.service
\n root# sudo -u chrony \/bin\/bash<\/p>\n

chrony$ cd \/run\/chrony
\n chrony$ ln -s \/etc\/shadow chronyd.pid
\n chrony$ exit<\/p>\n

root# \/usr\/sbin\/chronyd -n
\n ^C
\n # \u0432\u043c\u0435\u0441\u0442\u043e \u0441\u043e\u0434\u0435\u0440\u0436\u0438\u043c\u043e\u0433\u043e \/etc\/shadow \u0431\u0443\u0434\u0435\u0442 \u0441\u043e\u0445\u0440\u0430\u043d\u0451\u043d \u0438\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u0430 chronyd
\n root# cat \/etc\/shadow
\n 15287<\/p>\n

The vulnerability has been closed<\/a><\/noindex> in the release chrony 3.5.1<\/a><\/noindex>. Updates with vulnerability fixes are available for Alpine<\/a><\/noindex>. During the preparation of the update for SUSE\/openSUSE<\/a><\/noindex>, Debian<\/a><\/noindex> and Ubuntu<\/a><\/noindex>.<\/p>\n

SUSE and openSUSE on the issue as Exim is not included in their standard package repository.<\/a><\/noindex>, as the symbolic link for chrony is created directly in the \/run directory, without using additional subdirectories. <\/p>\n

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

Source: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 chrony, \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0430 NTP, \u043f\u0440\u0438\u043c\u0435\u043d\u044f\u0435\u043c\u043e\u0439 \u0434\u043b\u044f \u0441\u0438\u043d\u0445\u0440\u043e\u043d\u0438\u0437\u0430\u0446\u0438\u0438 \u0442\u043e\u0447\u043d\u043e\u0433\u043e \u0432\u0440\u0435\u043c\u0435\u043d\u0438 \u0432 \u0440\u0430\u0437\u043b\u0438\u0447\u043d\u044b\u0445 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 Linux, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2020-14367), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043f\u0435\u0440\u0435\u0437\u0430\u043f\u0438\u0441\u0430\u0442\u044c \u043b\u044e\u0431\u043e\u0439 \u0444\u0430\u0439\u043b \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435, \u0438\u043c\u0435\u044f \u0434\u043e\u0441\u0442\u0443\u043f \u043a \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u043c\u0443 \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e chrony. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043c\u043e\u0436\u0435\u0442 \u0431\u044b\u0442\u044c \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0430 \u0442\u043e\u043b\u044c\u043a\u043e \u0447\u0435\u0440\u0435\u0437 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f chrony, \u0447\u0442\u043e \u0441\u043d\u0438\u0436\u0430\u0435\u0442 \u0435\u0451 \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u044c. \u0422\u0435\u043c \u043d\u0435 \u043c\u0435\u043d\u0435\u0435, \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043a\u043e\u043c\u043f\u0440\u043e\u043c\u0435\u0442\u0438\u0440\u0443\u0435\u0442 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u0438\u0437\u043e\u043b\u044f\u0446\u0438\u0438 \u0432 chrony \u0438 \u043c\u043e\u0436\u0435\u0442 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u044c\u0441\u044f \u0432 […]<\/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-92097","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\udd47Vulnerability in chrony | ProHoster","description":"In chrony, the implementation of the NTP protocol used for synchronizing accurate time across various Linux 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