{"id":103053,"date":"2022-01-21T15:36:44","date_gmt":"2022-01-21T13:36:44","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-vfs-%d1%8f%d0%b4%d1%80%d0%b0-linux-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d0%bf%d0%be%d0%b2%d1%8b"},"modified":"2022-01-21T15:36:44","modified_gmt":"2022-01-21T13:36:44","slug":"%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-vfs-%d1%8f%d0%b4%d1%80%d0%b0-linux-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d0%bf%d0%be%d0%b2%d1%8b","status":"publish","type":"post","link":"https:\/\/prohoster.info\/ro\/blog\/news\/%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-vfs-%d1%8f%d0%b4%d1%80%d0%b0-linux-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d0%bf%d0%be%d0%b2%d1%8b","title":{"rendered":"Vulnerabilitate \u00een nucleul Linux VFS care permite eleva\u021bia privilegiilor","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

O vulnerabilitate a fost identificat\u0103 \u00een API-ul Filesystem Context furnizat de nucleul Linux (CVE-2022-0185), care permite unui utilizator local s\u0103 ob\u021bin\u0103 drepturi root \u00een sistem. Cercet\u0103torul care a descoperit problema a publicat o demonstra\u021bie a exploatului care permite executarea codului cu drepturi root pe Ubuntu 20.04 \u00een configura\u021bia implicit\u0103. Codul exploatat este planificat s\u0103 fie plasat pe GitHub \u00een decurs de o s\u0103pt\u0103m\u00e2n\u0103, dup\u0103 ce distribu\u021biile vor lansa o actualizare care s\u0103 remedieze vulnerabilitatea. <\/p>\n

Vulnerabilitatea se g\u0103se\u0219te \u00een func\u021bia legacy_parse_param() din VFS \u0219i este cauzat\u0103 de lipsa unei verific\u0103ri adecvate a dimensiunii maxime a parametrilor furniza\u021bi \u00een sistemele de fi\u0219iere care nu suport\u0103 API-ul Filesystem Context. C\u00e2nd se transmite un parametru prea mare, se poate produce un overflow al variabilei \u00eentregi utilizate pentru calcularea dimensiunii datelor scrise \u2014 \u00een cod exist\u0103 o verificare a dep\u0103\u0219irii limitei buffer-ului \u201eif (len > PAGE_SIZE - 2 - size)\u201d, care nu se activeaz\u0103 dac\u0103 valoarea size este mai mare de 4094 din cauza overflow-ului \u00eentregului prin sublimit\u0103 (integer underflow, c\u00e2nd se converte\u0219te 4096 - 2 - 4095 la unsigned int rezultatul va fi 2147483648). <\/p>\n

Aceast\u0103 eroare permite, prin accesarea unei imagini FS special concepute, o dep\u0103\u0219ire a buferei \u0219i suprascrierea datelor nucleului urm\u0103toare zonei de memorie alocate. Pentru a exploata vulnerabilitatea, sunt necesare drepturi CAP_SYS_ADMIN, adic\u0103 privilegii de administrator. Problema este c\u0103 un utilizator f\u0103r\u0103 privilegii poate ob\u021bine astfel de drepturi \u00eentr-un container izolat, dac\u0103 sistemul are activat\u0103 suportul pentru spa\u021biile de nume de identificatori de utilizatori (user namespaces). De exemplu, user namespaces sunt activate implicit \u00een Ubuntu \u0219i Fedora, dar nu sunt activate \u00een Debian \u0219i RHEL (cu excep\u021bia utiliz\u0103rii platformelor de izolare a containerelor). <\/p>\n

Problema apare \u00eencep\u00e2nd cu kernel-ul Linux 5.1 \u0219i a fost rezolvat\u0103 \u00een actualiz\u0103rile de ieri 5.16.2, 5.15.16, 5.10.93, 5.4.173. Actualiz\u0103rile pachetelor de remediere a vulnerabilit\u0103\u021bii au fost deja lansate pentru RHEL, Debian, Fedora, Ubuntu. Corectarea nu este \u00eenc\u0103 disponibil\u0103 \u00een Arch Linux, Gentoo, SUSE \u0219i openSUSE. Ca solu\u021bie temporar\u0103 de protec\u021bie pentru sistemele care nu utilizeaz\u0103 izola\u021bia containerelor, se poate seta valoarea sysctl \u201euser.max_user_namespaces\u201d la 0: echo \u201euser.max_user_namespaces=0\u201d > \/etc\/sysctl.d\/userns.conf # sysctl -p \/etc\/sysctl.d\/userns.conf
\n
Sursa: opennet.ro<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 API Filesystem Context, \u043f\u0440\u0435\u0434\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u043c\u044b\u043c \u044f\u0434\u0440\u043e\u043c Linux, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2022-0185), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u0434\u043e\u0431\u0438\u0442\u044c\u0441\u044f \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f \u043f\u0440\u0430\u0432 root \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435. \u0412\u044b\u044f\u0432\u0438\u0432\u0448\u0438\u0439 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0443 \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043b \u0434\u0435\u043c\u043e\u043d\u0441\u0442\u0440\u0430\u0446\u0438\u044e \u0440\u0430\u0431\u043e\u0442\u044b \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0435\u0433\u043e \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u043a\u043e\u0434 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 root \u0432 Ubuntu 20.04 \u0432 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u0438 \u043f\u043e \u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e. \u041a\u043e\u0434 \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430 \u043f\u043b\u0430\u043d\u0438\u0440\u0443\u0435\u0442\u0441\u044f \u0440\u0430\u0437\u043c\u0435\u0441\u0442\u0438\u0442\u044c \u043d\u0430 GitHub \u0432 \u0442\u0435\u0447\u0435\u043d\u0438\u0435 \u043d\u0435\u0434\u0435\u043b\u0438, \u043f\u043e\u0441\u043b\u0435 \u0442\u043e\u0433\u043e \u043a\u0430\u043a \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u044b \u0432\u044b\u043f\u0443\u0441\u0442\u044f\u0442 \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u0441 […]<\/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-103053","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\udd47Vulnerabilitate \u00een VFS-ul nucleului Linux, care permite cre\u0219terea privilegiilor | ProHoster","description":"O vulnerabilitate (CVE-2022-0185) a fost identificat\u0103 \u00een API-ul Filesystem Context, oferit de nucleul Linux, permi\u021b\u00e2nd unui utilizator local s\u0103 ob\u021bin\u0103 drepturi root \u00een 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