{"id":41582,"date":"2020-02-12T16:19:30","date_gmt":"2020-02-12T13:19:30","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/uyazvimost-v-systemd-potenczialno-pozvolyayushhaya-povysit-svoi-privilegii"},"modified":"2020-02-12T16:19:30","modified_gmt":"2020-02-12T13:19:30","slug":"uyazvimost-v-systemd-potenczialno-pozvolyayushhaya-povysit-svoi-privilegii","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/uyazvimost-v-systemd-potenczialno-pozvolyayushhaya-povysit-svoi-privilegii","title":{"rendered":"Zranitelnost v systemd, potenci\u00e1ln\u011b umo\u017e\u0148uj\u00edc\u00ed zv\u00fd\u0161en\u00ed privilegovan\u00fdch pr\u00e1v","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V syst\u00e9mov\u00e9m spr\u00e1vci systemd byla odhalena<\/a><\/noindex> zranitelnost (CVE-2020-1712<\/a><\/noindex>), kter\u00e1 potenci\u00e1ln\u011b umo\u017e\u0148uje prov\u00e9st vlastn\u00ed k\u00f3d s vy\u0161\u0161\u00edmi privilegii zasl\u00e1n\u00edm speci\u00e1ln\u011b form\u00e1tovan\u00e9 \u017e\u00e1dosti p\u0159es sb\u011brnici DBus. Probl\u00e9m byl opraven v testovac\u00ed verzi systemd 245-rc1<\/a><\/noindex> (\u0159e\u0161\u00edc\u00ed probl\u00e9m z\u00e1platy: 1<\/a><\/noindex>, 2<\/a><\/noindex>, 3<\/a><\/noindex>). Zranitelnost byla odstran\u011bna v distribuc\u00edch Ubuntu<\/a><\/noindex>, Fedora<\/a><\/noindex>, RHEL<\/a><\/noindex> (projevuje se v RHEL 8, ale net\u00fdk\u00e1 se RHEL 7), CentOS<\/a><\/noindex>, SUSE\/openSUSE<\/a><\/noindex> a ROSA<\/a><\/noindex>, ale k datu naps\u00e1n\u00ed t\u00e9to zpr\u00e1vy z\u016fst\u00e1v\u00e1 neopraven\u00e1 v Debian<\/a><\/noindex> a Arch Linux<\/a><\/noindex>. <\/p>\n

Zranitelnost je zp\u016fsobena p\u0159\u00edstupem k ji\u017e uvoln\u011bn\u00e9 oblasti pam\u011bti (use-after-free), kter\u00e1 se vyskytuje p\u0159i asynchronn\u00edm prov\u00e1d\u011bn\u00ed \u017e\u00e1dost\u00ed k Polkit b\u011bhem zpracov\u00e1n\u00ed zpr\u00e1v DBus. N\u011bkter\u00e9 DBus rozhran\u00ed pou\u017e\u00edvaj\u00ed cache k do\u010dasn\u00e9mu uchov\u00e1n\u00ed objekt\u016f a ma\u017eou prvky cache, jakmile je sb\u011brnice DBus uvoln\u011bn\u00e1 pro zpracov\u00e1n\u00ed dal\u0161\u00edch \u017e\u00e1dost\u00ed. Pokud zpracovatel DBus metody pou\u017e\u00edv\u00e1 bus_verify_polkit_async(), m\u016f\u017ee b\u00fdt nutn\u00e9 \u010dekat na dokon\u010den\u00ed akce v Polkit. Po p\u0159ipravenosti Polkit je zpracovatel vol\u00e1n znovu a p\u0159istupuje k ji\u017e d\u0159\u00edve alokovan\u00fdm dat\u016fm v pam\u011bti. Pokud je \u017e\u00e1dost k Polkit p\u0159\u00edli\u0161 dlouh\u00e1, prvky v cache maj\u00ed \u010das se vy\u010distit, je\u0161t\u011b ne\u017e je zpracovatel DBus metody vol\u00e1n podruh\u00e9. <\/p>\n

Mezi slu\u017ebami, kter\u00e9 umo\u017e\u0148uj\u00ed zneu\u017eit\u00ed zranitelnosti, je systemd-machined, kter\u00fd poskytuje DBus API org.freedesktop.machine1.Image.Clone, vedouc\u00ed k do\u010dasn\u00e9mu ulo\u017een\u00ed dat do cache a asynchronn\u00edmu p\u0159\u00edstupu k Polkit. Rozhran\u00ed
\norg.freedesktop.machine1.Image.Clone je dostupn\u00e9 v\u0161em nep\u0159id\u011blen\u00fdm u\u017eivatel\u016fm syst\u00e9mu, kte\u0159\u00ed mohou iniciovat p\u00e1d slu\u017eeb systemd nebo potenci\u00e1ln\u011b dos\u00e1hnout proveden\u00ed k\u00f3du s opr\u00e1vn\u011bn\u00edm root (prototyp exploitu zat\u00edm nebyl demonstrov\u00e1n). K\u00f3d umo\u017e\u0148uj\u00edc\u00ed zneu\u017eit\u00ed zranitelnosti byl p\u0159id\u00e1n<\/a><\/noindex> v systemd-machined od roku 2015 ve verzi systemd 220<\/a><\/noindex> (v RHEL 7.x se pou\u017e\u00edv\u00e1 systemd 219). <\/p>\n

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

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

\u0412 \u0441\u0438\u0441\u0442\u0435\u043c\u043d\u043e\u043c \u043c\u0435\u043d\u0435\u0434\u0436\u0435\u0440\u0435 systemd \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2020-1712), \u043a\u043e\u0442\u043e\u0440\u0430\u044f \u043f\u043e\u0442\u0435\u043d\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u0434\u043e\u0431\u0438\u0442\u044c\u0441\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u0441\u0432\u043e\u0435\u0433\u043e \u043a\u043e\u0434\u0430 \u0441 \u043f\u043e\u0432\u044b\u0448\u0435\u043d\u043d\u044b\u043c\u0438 \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u044f\u043c\u0438 \u0447\u0435\u0440\u0435\u0437 \u043e\u0442\u043f\u0440\u0430\u0432\u043a\u0443 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u043e\u0433\u043e \u0437\u0430\u043f\u0440\u043e\u0441\u0430 \u043f\u043e \u0448\u0438\u043d\u0435 DBus. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u0438\u0441\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0430 \u0432 \u0442\u0435\u0441\u0442\u043e\u0432\u043e\u043c \u0432\u044b\u043f\u0443\u0441\u043a\u0435 systemd 245-rc1 (\u0440\u0435\u0448\u0430\u044e\u0449\u0438\u0435 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0443 \u043f\u0430\u0442\u0447\u0438: 1, 2, 3). \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430 \u0432 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 Ubuntu, Fedora, RHEL (\u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0432 RHEL 8, \u043d\u043e \u043d\u0435 \u0437\u0430\u0442\u0440\u0430\u0433\u0438\u0432\u0430\u0435\u0442 RHEL 7), CentOS, 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