{"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\/cs\/blog\/news\/lokalnye-root-uyazvimosti-v-instrumentarii-upravleniya-paketami-snap","title":{"rendered":"Lok\u00e1ln\u00ed root-zranitelnosti v n\u00e1stroji pro spr\u00e1vu bal\u00edk\u016f Snap","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Spole\u010dnost Qualys zjistila dv\u011b zranitelnosti (CVE-2021-44731, CVE-2021-44730) v n\u00e1stroji snap-confine, dod\u00e1van\u00e9m s flagem SUID root a volan\u00e9m procesem snapd k vytvo\u0159en\u00ed spustiteln\u00e9ho prost\u0159ed\u00ed pro aplikace dod\u00e1van\u00e9 v sob\u011bsta\u010dn\u00fdch bal\u00ed\u010dc\u00edch ve form\u00e1tu snap. Zranitelnosti umo\u017e\u0148uj\u00ed m\u00edstn\u00edmu, neopr\u00e1vn\u011bn\u00e9mu u\u017eivateli spustit k\u00f3d s pr\u00e1vy root v syst\u00e9mu. Probl\u00e9my byly odstran\u011bny v dne\u0161n\u00edm aktualizaci bal\u00ed\u010dk\u016f snapd pro Ubuntu 21.10, 20.04 a 18.04. <\/p>\n

Prvn\u00ed zranitelnost (CVE-2021-44730) umo\u017e\u0148uje prov\u00e9st \u00fatok pomoc\u00ed manipulace s tvrd\u00fdmi odkazy, ale vy\u017eaduje deaktivaci syst\u00e9mov\u00e9 ochrany tvrd\u00fdch odkaz\u016f (nastaven\u00ed sysctl fs.protected_hardlinks na 0). Probl\u00e9m je zp\u016fsoben nespr\u00e1vnou kontrolou um\u00edst\u011bn\u00ed spustiteln\u00fdch soubor\u016f pomocn\u00fdch program\u016f snap-update-ns a snap-discard-ns, kter\u00e9 jsou spu\u0161t\u011bny s pr\u00e1vy root. Cesta k t\u011bmto soubor\u016fm byla vypo\u010d\u00edt\u00e1na ve funkci sc_open_snapd_tool() na z\u00e1klad\u011b vlastn\u00ed cesty z \/proc\/self\/exe, co\u017e umo\u017e\u0148uje vytvo\u0159it tvrd\u00fd odkaz na snap-confine ve sv\u00e9m adres\u00e1\u0159i a um\u00edstit do tohoto adres\u00e1\u0159e sv\u00e9 varianty n\u00e1stroj\u016f snap-update-ns a snap-discard-ns. Po spu\u0161t\u011bn\u00ed p\u0159es tvrd\u00fd odkaz snap-confine s pr\u00e1vy root spust\u00ed z aktu\u00e1ln\u00edho adres\u00e1\u0159e soubory snap-update-ns a snap-discard-ns, kter\u00e9 poskytl \u00fato\u010dn\u00edk. <\/p>\n

Druh\u00e1 zranitelnost je zp\u016fsobena z\u00e1vodem a m\u016f\u017ee b\u00fdt zneu\u017eita v konfiguraci Ubuntu Desktop ve v\u00fdchoz\u00edm nastaven\u00ed. Pro \u00fasp\u011b\u0161n\u00e9 fungov\u00e1n\u00ed exploitace v Ubuntu Server je pot\u0159eba p\u0159i instalaci vybrat jeden z bal\u00edk\u016f v sekci «Featured Server Snaps». Z\u00e1vod se projevuje ve funkci setup_private_mount(), kter\u00e1 je vol\u00e1na b\u011bhem p\u0159\u00edpravy prostoru n\u00e1zv\u016f pro body p\u0159ipojen\u00ed pro bal\u00edk snap. Tato funkce vytv\u00e1\u0159\u00ed do\u010dasn\u00fd adres\u00e1\u0159 « \/tmp\/snap.$SNAP_NAME\/tmp » nebo pou\u017eije ji\u017e existuj\u00edc\u00ed pro bind-montov\u00e1n\u00ed do n\u011bj adres\u00e1\u0159\u016f pro bal\u00edk ve form\u00e1tu snap. <\/p>\n

Jeliko\u017e je n\u00e1zev do\u010dasn\u00e9ho adres\u00e1\u0159e p\u0159edv\u00eddateln\u00fd, \u00fato\u010dn\u00edk m\u016f\u017ee nahradit jeho obsah symbolick\u00fdm odkazem v dob\u011b po kontrole vlastn\u00edka, ale p\u0159ed vol\u00e1n\u00edm syst\u00e9mov\u00e9ho vol\u00e1n\u00ed mount. Nap\u0159\u00edklad lze vytvo\u0159it v adres\u00e1\u0159i \/tmp\/snap.lxd symbolick\u00fd odkaz « \/tmp\/snap.lxd\/tmp », kter\u00fd ukazuje na libovoln\u00fd adres\u00e1\u0159, a vol\u00e1n\u00ed mount() n\u00e1sledn\u011b prob\u011bhne p\u0159es symbolick\u00fd odkaz a p\u0159imontuje adres\u00e1\u0159 do prostoru n\u00e1zv\u016f snap. T\u00edmto zp\u016fsobem lze p\u0159imontovat sv\u016fj obsah do \/var\/lib a p\u0159es nahrazen\u00ed \/var\/lib\/snapd\/mount\/snap.snap-store.user-fstab uspo\u0159\u00e1dat p\u0159imontov\u00e1n\u00ed sv\u00e9ho adres\u00e1\u0159e \/etc do prostoru n\u00e1zv\u016f snap-paketu pro zaji\u0161t\u011bn\u00ed nahr\u00e1n\u00ed sv\u00e9 knihovny s pr\u00e1vy root pomoc\u00ed nahrazen\u00ed \/etc\/ld.so.preload. <\/p>\n

Upozor\u0148uje se, \u017ee vytvo\u0159en\u00ed exploit bylo netrivi\u00e1ln\u00ed \u00fakol, proto\u017ee n\u00e1stroj snap-confine je naps\u00e1n v jazyce Go s vyu\u017eit\u00edm bezpe\u010dnostn\u00edch programovac\u00edch praktik, m\u00e1 ochranu zalo\u017eenou na profilech AppArmor, prov\u00e1d\u00ed filtrov\u00e1n\u00ed syst\u00e9mov\u00fdch vol\u00e1n\u00ed na z\u00e1klad\u011b mechanismu seccomp a pou\u017e\u00edv\u00e1 pro izolaci prostor jmen pro mont\u00e1\u017e. Nicm\u00e9n\u011b, v\u00fdzkumn\u00edk\u016fm se poda\u0159ilo p\u0159ipravit funk\u010dn\u00ed exploit pro z\u00edsk\u00e1n\u00ed pr\u00e1v root v syst\u00e9mu. K\u00f3d exploitu bude zve\u0159ejn\u011bn za n\u011bkolik t\u00fddn\u016f, po tom, co u\u017eivatel\u00e9 nainstaluj\u00ed poskytnut\u00e9 aktualizace.
\n
Zdroj: 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\udd47Lok\u00e1ln\u00ed root zranitelnosti v n\u00e1stroj\u00edch pro spr\u00e1vu bal\u00ed\u010dk\u016f Snap | ProHoster","description":"Spole\u010dnost Qualys odhalila dv\u011b zranitelnosti (CVE-2021-44731, CVE-2021-44730) v n\u00e1stroji snap-confine, dod\u00e1van\u00e9m s flagem SUID root a vyvol\u00e1van\u00e9m procesem snapd pro vytv\u00e1\u0159en\u00ed spustiteln\u00e9ho prost\u0159ed\u00ed pro aplikace.","canonical_url":"https:\/\/prohoster.info\/cs\/blog\/news\/lokalnye-root-uyazvimosti-v-instrumentarii-upravleniya-paketami-snap","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"cs_CZ","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\udd47\u041b\u043e\u043a\u0430\u043b\u044c\u043d\u044b\u0435 root-\u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 \u0438\u043d\u0441\u0442\u0440\u0443\u043c\u0435\u043d\u0442\u0430\u0440\u0438\u0438 \u0443\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u044f \u043f\u0430\u043a\u0435\u0442\u0430\u043c\u0438 Snap | ProHoster","og:description":"\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.","og:url":"https:\/\/prohoster.info\/cs\/blog\/news\/lokalnye-root-uyazvimosti-v-instrumentarii-upravleniya-paketami-snap","og:image":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:secure_url":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:width":350,"og:image:height":350,"article:published_time":"2022-02-18T01:37:22+00:00","article:modified_time":"2022-02-18T01:37:22+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster","article:author":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":{"post_id":"103374","title":null,"description":null,"keywords":null,"keyphrases":null,"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":"default","schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"seo_analyzer_scan_date":null,"breadcrumb_settings":null,"limit_modified_date":false,"reviewed_by":null,"ai":null,"created":"2022-02-18 01:37:39","updated":"2022-10-10 21:24:34","focus_keyword":null,"additional_keywords":null,"truseo_locale":null},"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/103374","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/comments?post=103374"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/103374\/revisions"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/media?parent=103374"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/categories?post=103374"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/tags?post=103374"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}