Spolo\u010dnos\u0165 Qualys odhalila zranite\u013enos\u0165 (CVE-2025-6019) v kni\u017enici libblockdev, ktor\u00e1 umo\u017e\u0148uje z\u00edska\u0165 pr\u00e1va root v syst\u00e9me prostredn\u00edctvom manipul\u00e1cie s pozad\u00edm procesu udisks. Fungovanie prototypu exploit-u bolo demon\u0161trovan\u00e9 na Ubuntu, Debian, Fedora a openSUSE Leap 15. <\/p>\n
Proces udisks sa pou\u017e\u00edva prakticky vo v\u0161etk\u00fdch distrib\u00faci\u00e1ch Linuxu a poskytuje rozhranie D-Bus na vykon\u00e1vanie oper\u00e1ci\u00ed s \u00falo\u017eiskami, ako je montovanie a form\u00e1tovanie. Na vykon\u00e1vanie akci\u00ed s \u00falo\u017eiskami udisks vol\u00e1 funkcie kni\u017enice libblockdev. Pr\u00edstup k udisks je predvolene otvoren\u00fd iba pre pou\u017e\u00edvate\u013eov, ktor\u00ed pracuj\u00fa v kontexte 'allow_active', t.j. t\u00fdch, ktor\u00ed maj\u00fa fyzick\u00fd pr\u00edstup k po\u010d\u00edta\u010du a pripojili sa prostredn\u00edctvom lok\u00e1lnej konzoly alebo spustili grafick\u00fa rel\u00e1ciu. Pou\u017e\u00edvatelia, ktor\u00ed sa prip\u00e1jaj\u00fa na dia\u013eku, napr\u00edklad cez ssh, do tohto kontextu nepatria a nem\u00f4\u017eu priamo zneu\u017ei\u0165 zranite\u013enos\u0165. <\/p>\n
Na ob\u00eddenie tohto obmedzenia je mo\u017en\u00e9 pou\u017ei\u0165 trik, ktor\u00fd umo\u017e\u0148uje zv\u00fd\u0161i\u0165 \u00farove\u0148 autentifik\u00e1cie na 'allow_active' prostredn\u00edctvom manipul\u00e1ci\u00ed so spusten\u00edm utilitou systemctl pou\u017e\u00edvate\u013eskej slu\u017eby, ktor\u00fa polkitd vn\u00edma ako znak lok\u00e1lnej rel\u00e1cie. Podstatou met\u00f3dy je, \u017ee polkitd ur\u010duje pr\u00edtomnos\u0165 fyzick\u00e9ho pr\u00edstupu a pride\u013euje \u00farove\u0148 'allow_active' na z\u00e1klade nepriamej indik\u00e1cie, na ktor\u00e9 je mo\u017en\u00e9 vpl\u00fdva\u0165. Obmedzenia met\u00f3dy spo\u010d\u00edvaj\u00fa v tom, \u017ee na oklamanie polkitd je potrebn\u00e9, aby bol v syst\u00e9me u\u017e akt\u00edvny rel\u00e1cia lok\u00e1lneho pou\u017e\u00edvate\u013ea s fyzick\u00fdm pr\u00edstupom. <\/p>\n
Druh\u00fdm sp\u00f4sobom, ako z\u00edska\u0165 pr\u00e1va 'allow_active', je zneu\u017ei\u0165 zranite\u013enos\u0165 (CVE-2025-6018) v PAM (Pluggable Authentication Modules), ktor\u00fa v\u00fdskumn\u00edci z Qualys identifikovali po\u010das anal\u00fdzy zranite\u013enosti v libblockdev. Zranite\u013enos\u0165 umo\u017e\u0148uje ak\u00e9muko\u013evek pou\u017e\u00edvate\u013eovi, vr\u00e1tane t\u00fdch, ktor\u00ed sa pripojili cez SSH, vykon\u00e1va\u0165 oper\u00e1cie v kontexte 'allow_active'. Probl\u00e9m je \u0161pecifick\u00fd pre nastavenia PAM v openSUSE Leap 15 a SUSE Linux Enterprise 15 a prejavuje sa iba v t\u00fdchto distrib\u00faci\u00e1ch. <\/p>\n
V module pam_env v openSUSE a SUSE je predvolene zapnut\u00e9 \u010d\u00edtanie s\u00faboru ~\/.pam_environment. Cez tento s\u00fabor m\u00f4\u017ee pou\u017e\u00edvate\u013e nastavi\u0165 premenn\u00e9 prostredia XDG_SEAT=seat0 a XDG_VTNR=1, ktor\u00e9 bud\u00fa pri \u010fal\u0161ej spracovan\u00ed pova\u017eovan\u00e9 za zn\u00e1mku fyzickej pr\u00edtomnosti pou\u017e\u00edvate\u013ea, aj ke\u010f sa prihl\u00e1senie vykon\u00e1va cez SSH. Modul pam_env sa tie\u017e vol\u00e1 pri pripojen\u00ed cez ssh v Debian 12 a Ubuntu 24.04 (v Debian 13 a Ubuntu 24.10+ je vypnut\u00fd), ale nastavenie premenn\u00fdch prostredia v t\u00fdchto distrib\u00faci\u00e1ch nem\u00f4\u017ee by\u0165 pou\u017eit\u00e9 na zv\u00fd\u0161enie \u00farovne pr\u00edstupu na 'allow_active', preto\u017ee pam_env sa vol\u00e1 na kone\u010dnej f\u00e1ze po na\u010d\u00edtan\u00ed modulu pam_systemd a nastaven\u00e9 premenn\u00e9 prostredia nem\u00f4\u017eu ovplyvni\u0165 parametre rel\u00e1cie. <\/p>\n
Pokia\u013e ide o zranite\u013enos\u0165 v libblockdev, \u00fato\u010dn\u00edk m\u00f4\u017ee pripoji\u0165 obraz \u013eubovo\u013en\u00e9ho s\u00faborov\u00e9ho syst\u00e9mu v loop-re\u017eime, umiestni\u0165 do tohto obrazu vykon\u00e1vac\u00ed s\u00fabor s pr\u00edznakom SUID root alebo \u0161peci\u00e1lne zariadenie (\/dev\/mem) pre n\u00edzko\u00farov\u0148ov\u00fd pr\u00edstup k diskov\u00e9mu alebo pam\u00e4\u0165ov\u00e9mu \u00falo\u017eisku. Na blokovanie podobn\u00fdch \u00fatokov s\u00fa obrazy FS pripojen\u00e9 syst\u00e9mom s pr\u00edznakmi nosuid a nodev, ale zranite\u013enos\u0165 v libblockdev umo\u017e\u0148uje pripoji\u0165 obraz bez pr\u00edznakov nosuid a nodev. Podstatou zranite\u013enosti je, \u017ee udisks umo\u017e\u0148uje pou\u017e\u00edvate\u013eovi s pr\u00edstupom 'allow_active' zmeni\u0165 ve\u013ekos\u0165 svojich s\u00faborov\u00fdch syst\u00e9mov a libblockdev po\u010das vykon\u00e1vania tejto oper\u00e1cie do\u010dasne montuje FS bez nastavenia pr\u00edznakov nosuid a nodev. <\/p>\n
Takto sa \u00fatok redukuje na vytvorenie loop-zariadenia na z\u00e1klade obrazu FS XFS, v ktorom je umiestnen\u00fd suid root s\u00fabor, iniciovanie oper\u00e1cie zmeny ve\u013ekosti loop-zariadenia a sledovanie okamihu jeho pripojenia do adres\u00e1ra \/tmp\/blockdev*: victim> killall -KILL gvfs-udisks2-volume-monitor victim> udisksctl loop-setup --file .\/xfs.image --no-user-interaction Mapped file .\/xfs.image as \/dev\/loop0. victim> while true; do \/tmp\/blockdev*\/bash -c 'sleep 10; ls -l \/tmp\/blockdev*\/bash' && break; done 2>\/dev\/null & victim> gdbus call --system --dest org.freedesktop.UDisks2 --object-path \/org\/freedesktop\/UDisks2\/block_devices\/loop0 --method org.freedesktop.UDisks2.Filesystem.Resize 0 '{}' Error: GDBus.Error:org.freedesktop.UDisks2.Error.Failed: Error resizing filesystem on \/dev\/loop0: Failed to unmount '\/dev\/loop0' after resizing it: target is busy -r-sr-xr-x. 1 root root 1406608 Jun 18 09:42 \/tmp\/blockdev.RSM429\/bash victim> \/tmp\/blockdev*\/bash -p victim# id uid=65534(nobody) gid=65534(nobody) euid=0(root) groups=65534(nobody) <\/p>\n
Zranite\u013enos\u0165 v libblockdev bola zatia\u013e opraven\u00e1 iba prostredn\u00edctvom z\u00e1plat. Stav novej verzie bal\u00edka alebo pr\u00edpravy opravy v distrib\u00faci\u00e1ch mo\u017eno skontrolova\u0165 na nasleduj\u00facich str\u00e1nkach (ak je str\u00e1nka nedostupn\u00e1, znamen\u00e1 to, \u017ee v\u00fdvoj\u00e1ri distrib\u00facie sa e\u0161te neza\u010dali zaobera\u0165 probl\u00e9mom): Debian, Ubuntu, Fedora, SUSE\/openSUSE, RHEL, Gentoo a Arch (1, 2). Ako obch\u00e1dzaj\u00face rie\u0161enie na zablokovanie zranite\u013enosti je mo\u017en\u00e9 zmeni\u0165 pravidlo pr\u00edstupu k oper\u00e1cii \u201eorg.freedesktop.udisks2.modify-device\u201c v polkit, zmenou hodnoty parametra \u201eallow_active\u201c v s\u00fabore \/usr\/share\/polkit-1\/actions\/org.freedesktop.UDisks2.policy z \u201eyes\u201c na \u201eauth_admin\u201c. <\/p>\n
Navy\u0161e m\u00f4\u017eeme spomen\u00fa\u0165 zranite\u013enos\u0165 (CVE-2025-6020), ktor\u00e1 bola odhalen\u00e1 pred nieko\u013ek\u00fdmi hodinami v bal\u00edku linux-pam, ktor\u00e1 umo\u017e\u0148uje lok\u00e1lnemu pou\u017e\u00edvate\u013eovi z\u00edska\u0165 pr\u00e1va root. Modul pam_namespace spr\u00e1vne nekontroloval s\u00faborov\u00e9 cesty kontrolovan\u00e9 pou\u017e\u00edvate\u013eom, \u010do umo\u017enilo manipulova\u0165 so symbolick\u00fdmi odkazmi a dosiahnu\u0165 stav z\u00e1vodu, \u010d\u00edm do\u0161lo k prepisovaniu privilegovan\u00fdch s\u00faborov v syst\u00e9me. Zranite\u013enos\u0165 bola odstr\u00e1nen\u00e1 v vydan\u00ed linux-pam 1.7.1. Stav novej verzie bal\u00edka alebo pr\u00edpravy opravy v distrib\u00faci\u00e1ch si m\u00f4\u017eete overi\u0165 na nasleduj\u00facich str\u00e1nkach: Debian, Ubuntu, Fedora, SUSE\/openSUSE, RHEL, Gentoo a Arch (1, 2). \u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Qualys \u0432\u044b\u044f\u0432\u0438\u043b\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2025-6019) \u0432 \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0435 libblockdev, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0443\u044e \u0447\u0435\u0440\u0435\u0437 \u043c\u0430\u043d\u0438\u043f\u0443\u043b\u044f\u0446\u0438\u0438 \u0441 \u0444\u043e\u043d\u043e\u0432\u044b\u043c \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u043c udisks \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u043f\u0440\u0430\u0432\u0430 root \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435. \u0420\u0430\u0431\u043e\u0442\u0430 \u043f\u0440\u043e\u0442\u043e\u0442\u0438\u043f\u0430 \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430 \u043f\u0440\u043e\u0434\u0435\u043c\u043e\u043d\u0441\u0442\u0440\u0438\u0440\u043e\u0432\u0430\u043d\u0430 \u0432 Ubuntu, Debian, Fedora \u0438 openSUSE Leap 15. \u041f\u0440\u043e\u0446\u0435\u0441\u0441 udisks \u043f\u0440\u0438\u043c\u0435\u043d\u044f\u0435\u0442\u0441\u044f \u043f\u0440\u0430\u043a\u0442\u0438\u0447\u0435\u0441\u043a\u0438 \u0432\u043e \u0432\u0441\u0435\u0445 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 Linux \u0438 \u043f\u0440\u0435\u0434\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 \u0438\u043d\u0442\u0435\u0440\u0444\u0435\u0439\u0441 D-Bus \u0434\u043b\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u0439 \u0441 \u043d\u0430\u043a\u043e\u043f\u0438\u0442\u0435\u043b\u044f\u043c\u0438, \u0442\u0430\u043a\u0438\u0445 \u043a\u0430\u043a \u043c\u043e\u043d\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0438 \u0444\u043e\u0440\u043c\u0430\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435. \u0414\u043b\u044f […]<\/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-137763","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\udd47Zranite\u013enosti v PAM a libblockdev, ktor\u00e9 umo\u017e\u0148uj\u00fa z\u00edska\u0165 pr\u00e1va root v syst\u00e9me | ProHoster","description":"Spolo\u010dnos\u0165 Qualys odhalila zranite\u013enos\u0165 (CVE-2025-6019) v kni\u017enici libblockdev, ktor\u00e1 umo\u017e\u0148uje z\u00edska\u0165 pr\u00e1va root v syst\u00e9me manipul\u00e1ciou s pozad\u00edm procesu udisks.","canonical_url":"https:\/\/prohoster.info\/sk\/blog\/news\/uyazvimosti-v-pam-i-libblockdev-pozvolyayushhie-poluchit-prava-root-v-sisteme","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"sk_SK","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\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 PAM \u0438 libblockdev, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0438\u0435 \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c 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Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"