{"id":103374,"date":"2022-02-18T03:37:22","date_gmt":"2022-02-18T01:37:22","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/lokalnye-root-uyazvimosti-v-instrumentarii-upravleniya-paketami-snap"},"modified":"2022-02-18T03:37:22","modified_gmt":"2022-02-18T01:37:22","slug":"lokalnye-root-uyazvimosti-v-instrumentarii-upravleniya-paketami-snap","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sv\/blog\/news\/lokalnye-root-uyazvimosti-v-instrumentarii-upravleniya-paketami-snap","title":{"rendered":"Lokala root-s\u00e5rbarheter i Snap-pakethanteringsverktyget","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

F\u00f6retaget Qualys har identifierat tv\u00e5 s\u00e5rbarheter (CVE-2021-44731, CVE-2021-44730) i verktyget snap-confine, som levereras med SUID root-flagga och anropas av processen snapd f\u00f6r att skapa en k\u00f6rmilj\u00f6 f\u00f6r applikationer som levereras i sj\u00e4lvb\u00e4rande paket i snap-format. S\u00e5rbarheterna g\u00f6r det m\u00f6jligt f\u00f6r en lokal icke-privilegierad anv\u00e4ndare att k\u00f6ra kod med root-r\u00e4ttigheter i systemet. Problemet har \u00e5tg\u00e4rdats i dagens uppdatering av snapd-paketen f\u00f6r Ubuntu 21.10, 20.04 och 18.04. <\/p>\n

Den f\u00f6rsta s\u00e5rbarheten (CVE-2021-44730) m\u00f6jligg\u00f6r en attack genom manipulering av h\u00e5rda l\u00e4nkar, men kr\u00e4ver att den systeminbyggda skyddet f\u00f6r h\u00e5rda l\u00e4nkar \u00e4r inaktiverat (inst\u00e4llning av sysctl fs.protected_hardlinks till 0). Problemet orsakas av felaktig kontroll av platsen f\u00f6r k\u00f6rbara filer f\u00f6r hj\u00e4lpprogrammen snap-update-ns och snap-discard-ns, som k\u00f6rs med root-r\u00e4ttigheter. S\u00f6kv\u00e4gen till dessa filer ber\u00e4knades i funktionen sc_open_snapd_tool() baserat p\u00e5 sin egen s\u00f6kv\u00e4g fr\u00e5n \/proc\/self\/exe, vilket g\u00f6r det m\u00f6jligt att skapa en h\u00e5rd l\u00e4nk till snap-confine i sin egen mapp och placera sina egna versioner av snap-update-ns och snap-discard-ns i denna mapp. Efter att ha startat via h\u00e5rda l\u00e4nken kommer snap-confine med root-r\u00e4ttigheter att k\u00f6ra de filer av snap-update-ns och snap-discard-ns som attackeraren har placerat i den aktuella mappen. <\/p>\n

\u0412\u0442\u043e\u0440\u0430\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432\u044b\u0437\u0432\u0430\u043d\u0430 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435\u043c \u0433\u043e\u043d\u043a\u0438 \u0438 \u043c\u043e\u0436\u0435\u0442 \u0431\u044b\u0442\u044c \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0430 \u0432 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u0438 Ubuntu Desktop \u043f\u043e \u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e. \u0414\u043b\u044f \u0443\u0441\u043f\u0435\u0448\u043d\u043e\u0439 \u0440\u0430\u0431\u043e\u0442\u044b \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430 \u0432 Ubuntu Server \u0442\u0440\u0435\u0431\u0443\u0435\u0442\u0441\u044f \u0432\u044b\u0431\u043e\u0440 \u043f\u0440\u0438 \u0443\u0441\u0442\u0430\u043d\u043e\u0432\u043a\u0435 \u043e\u0434\u043d\u043e\u0433\u043e \u0438\u0437 \u043f\u0430\u043a\u0435\u0442\u043e\u0432 \u0438\u0437 \u0441\u0435\u043a\u0446\u0438\u0438 «Featured Server Snaps». \u0421\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435 \u0433\u043e\u043d\u043a\u0438 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0432 \u0444\u0443\u043d\u043a\u0446\u0438\u0438 setup_private_mount(), \u0432\u044b\u0437\u044b\u0432\u0430\u0435\u043c\u043e\u0439 \u0432\u043e \u0432\u0440\u0435\u043c\u044f \u043f\u043e\u0434\u0433\u043e\u0442\u043e\u0432\u043a\u0438 \u043f\u0440\u043e\u0441\u0442\u0440\u0430\u043d\u0441\u0442\u0432\u0430 \u0438\u043c\u0451\u043d \u0442\u043e\u0447\u0435\u043a \u043c\u043e\u043d\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u0434\u043b\u044f \u043f\u0430\u043a\u0435\u0442\u0430 snap. \u0414\u0430\u043d\u043d\u0430\u044f \u0444\u0443\u043d\u043a\u0446\u0438\u044f \u0441\u043e\u0437\u0434\u0430\u0451\u0442 \u0432\u0440\u0435\u043c\u0435\u043d\u043d\u044b\u0439 \u043a\u0430\u0442\u0430\u043b\u043e\u0433 «\/tmp\/snap.$SNAP_NAME\/tmp» \u0438\u043b\u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u0442 \u0443\u0436\u0435 \u0441\u0443\u0449\u0435\u0441\u0442\u0432\u0443\u044e\u0449\u0438\u0439 \u0434\u043b\u044f bind-\u043c\u043e\u043d\u0442\u0438\u0440\u043e\u0432\u043d\u0438\u044f \u0432 \u043d\u0435\u0433\u043e \u043a\u0430\u0442\u0430\u043b\u043e\u0433\u043e\u0432 \u0434\u043b\u044f \u043f\u0430\u043a\u0435\u0442\u0430 \u0432 \u0444\u043e\u0440\u043c\u0430\u0442\u0435 snap. <\/p>\n

\u0422\u0430\u043a \u043a\u0430\u043a \u0438\u043c\u044f \u0432\u0440\u0435\u043c\u0435\u043d\u043d\u043e\u0433\u043e \u043a\u0430\u0442\u0430\u043b\u043e\u0433\u0430 \u043f\u0440\u0435\u0434\u0441\u043a\u0430\u0437\u0443\u0435\u043c\u043e, \u0430\u0442\u0430\u043a\u0443\u044e\u0449\u0438\u0439 \u043c\u043e\u0436\u0435\u0442 \u043f\u043e\u0434\u043c\u0435\u043d\u0438\u0442\u044c \u0435\u0433\u043e \u0441\u043e\u0434\u0435\u0440\u0436\u0438\u043c\u043e\u0435 \u043d\u0430 \u0441\u0438\u043c\u0432\u043e\u043b\u0438\u0447\u0435\u0441\u043a\u0443\u044e \u0441\u0441\u044b\u043b\u043a\u0443 \u0432 \u043c\u043e\u043c\u0435\u043d\u0442 \u043f\u043e\u0441\u043b\u0435 \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0438 \u0432\u043b\u0430\u0434\u0435\u043b\u044c\u0446\u0430, \u043d\u043e \u043f\u0435\u0440\u0435\u0434 \u043e\u0431\u0440\u0430\u0449\u0435\u043d\u0438\u0435\u043c \u043a \u0441\u0438\u0441\u0442\u0435\u043c\u043d\u043e\u043c\u0443 \u0432\u044b\u0437\u043e\u0432\u0443 mount. \u041d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, \u043c\u043e\u0436\u043d\u043e \u0441\u043e\u0437\u0434\u0430\u0442\u044c \u0432 \u043a\u0430\u0442\u0430\u043b\u043e\u0433\u0435 \/tmp\/snap.lxd \u0441\u0438\u043c\u0432\u043e\u043b\u0438\u0447\u0435\u0441\u043a\u0443\u044e \u0441\u0441\u044b\u043b\u043a\u0443 «\/tmp\/snap.lxd\/tmp», \u0443\u043a\u0430\u0437\u044b\u0432\u0430\u044e\u0449\u0443\u044e \u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u043b\u044c\u043d\u044b\u0439 \u043a\u0430\u0442\u0430\u043b\u043e\u0433, \u0438 \u0432\u044b\u0437\u043e\u0432 mount() \u043f\u043e\u0441\u043b\u0435\u0434\u0443\u0435\u0442 \u0437\u0430 \u0441\u0438\u043c\u0432\u043e\u043b\u0438\u0447\u0435\u0441\u043a\u043e\u0439 \u0441\u0441\u044b\u043b\u043a\u043e\u0439 \u0438 \u043f\u0440\u0438\u043c\u043e\u043d\u0442\u0438\u0440\u0443\u0435\u0442 \u043a\u0430\u0442\u0430\u043b\u043e\u0433 \u0432 \u043f\u0440\u043e\u0441\u0442\u0440\u0430\u043d\u0441\u0442\u0432\u0435 \u0438\u043c\u0451\u043d snap. \u041f\u043e\u0434\u043e\u0431\u043d\u044b\u043c \u043e\u0431\u0440\u0430\u0437\u043e\u043c \u043c\u043e\u0436\u043d\u043e \u043f\u0440\u0438\u043c\u043e\u043d\u0442\u0438\u0440\u043e\u0432\u0430\u0442\u044c \u0441\u0432\u043e\u0451 \u0441\u043e\u0434\u0435\u0440\u0436\u0438\u043c\u043e\u0435 \u0432 \/var\/lib \u0438 \u0447\u0435\u0440\u0435\u0437 \u0437\u0430\u043c\u0435\u043d\u0443 \/var\/lib\/snapd\/mount\/snap.snap-store.user-fstab \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u043e\u0432\u0430\u0442\u044c \u043c\u043e\u043d\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0441\u0432\u043e\u0435\u0433\u043e \u043a\u0430\u0442\u0430\u043b\u043e\u0433\u0430 \/etc \u0432 \u043f\u0440\u043e\u0441\u0442\u0440\u0430\u043d\u0441\u0442\u0432\u0435 \u0438\u043c\u0451\u043d snap-\u043f\u0430\u043a\u0435\u0442\u0430 \u0434\u043b\u044f \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u0430\u0446\u0438\u0438 \u0437\u0430\u0433\u0440\u0443\u0437\u043a\u0438 \u0441\u0432\u043e\u0435\u0439 \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0438 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 root \u0447\u0435\u0440\u0435\u0437 \u0437\u0430\u043c\u0435\u043d\u0443 \/etc\/ld.so.preload. <\/p>\n

Det noteras att skapandet av en exploit visade sig vara en icke-trivial uppgift, eftersom verktyget snap-confine \u00e4r skrivet i spr\u00e5k Go med anv\u00e4ndning av s\u00e4kra programmeringstekniker, har skydd baserat p\u00e5 AppArmor-profiler, filtrerar systemanrop baserat p\u00e5 seccomp-mekanismen och till\u00e4mpar namnrymd f\u00f6r montering f\u00f6r isolering. Trots detta lyckades forskarna f\u00f6rbereda en fungerande exploit f\u00f6r att f\u00e5 root-r\u00e4ttigheter i systemet. Koden f\u00f6r exploiten kommer att publiceras inom n\u00e5gra veckor, efter att anv\u00e4ndarna har installerat de tillhandah\u00e5llna uppdateringarna.
\n
K\u00e4lla: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Qualys \u0432\u044b\u044f\u0432\u0438\u043b\u0430 \u0434\u0432\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 (CVE-2021-44731, CVE-2021-44730) \u0432 \u0443\u0442\u0438\u043b\u0438\u0442\u0435 snap-confine, \u043f\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u043c\u043e\u0439 \u0441 \u0444\u043b\u0430\u0433\u043e\u043c SUID root \u0438 \u0432\u044b\u0437\u044b\u0432\u0430\u0435\u043c\u043e\u0439 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u043c snapd \u0434\u043b\u044f \u0444\u043e\u0440\u043c\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u0438\u0441\u043f\u043e\u043b\u043d\u044f\u0435\u043c\u043e\u0433\u043e \u043e\u043a\u0440\u0443\u0436\u0435\u043d\u0438\u044f \u0434\u043b\u044f \u043f\u0440\u0438\u043b\u043e\u0436\u0435\u043d\u0438\u0439, \u043f\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u043c\u044b\u0445 \u0432 \u0441\u0430\u043c\u043e\u0434\u043e\u0441\u0442\u0430\u0442\u043e\u0447\u043d\u044b\u0445 \u043f\u0430\u043a\u0435\u0442\u0430\u0445 \u0432 \u0444\u043e\u0440\u043c\u0430\u0442\u0435 snap. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0442 \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 \u0434\u043e\u0431\u0438\u0442\u044c\u0441\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u043a\u043e\u0434\u0430 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 root \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u044b \u0432 \u0441\u0435\u0433\u043e\u0434\u043d\u044f\u0448\u043d\u0435\u043c \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0438 \u043f\u0430\u043a\u0435\u0442\u043e\u0432 snapd \u0434\u043b\u044f Ubuntu 21.10, […]<\/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-103374","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\udd47Lokala root-s\u00e5rbarheter i Snap pakethanteringsverktyg | ProHoster","description":"F\u00f6retaget Qualys har identifierat tv\u00e5 s\u00e5rbarheter (CVE-2021-44731, CVE-2021-44730) i verktyget snap-confine, vilket levereras med SUID root-flagg och \u00e5beropas av processen snapd 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