{"id":99421,"date":"2021-03-13T22:22:39","date_gmt":"2021-03-13T20:22:40","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-podsisteme-iscsi-yadra-linux-pozvolyayushhaya-podnyat-svoi-privilegii"},"modified":"2021-03-13T22:22:39","modified_gmt":"2021-03-13T20:22:40","slug":"uyazvimost-v-podsisteme-iscsi-yadra-linux-pozvolyayushhaya-podnyat-svoi-privilegii","status":"publish","type":"post","link":"https:\/\/prohoster.info\/hu\/blog\/news\/uyazvimost-v-podsisteme-iscsi-yadra-linux-pozvolyayushhaya-podnyat-svoi-privilegii","title":{"rendered":"A vulnerabilit\u00e1s a Linux kernel iSCSI alrendszer\u00e9ben, amely lehet\u0151v\u00e9 teszi a jogosults\u00e1gok megszerz\u00e9s\u00e9t.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Az iSCSI alrendszer k\u00f3dj\u00e1ban felfedeztek egy sebezhet\u0151s\u00e9get (CVE-2021-27365), amely lehet\u0151v\u00e9 teszi egy nem privilegiz\u00e1lt helyi felhaszn\u00e1l\u00f3 sz\u00e1m\u00e1ra, hogy k\u00f3dot hajtson v\u00e9gre a kernel szintj\u00e9n, \u00e9s root jogosults\u00e1gokat szerezzen a rendszerben. A sebezhet\u0151s\u00e9g tesztel\u00e9s\u00e9re m\u0171k\u00f6d\u0151 protot\u00edpus exploit \u00e9rhet\u0151 el. A sebezhet\u0151s\u00e9get jav\u00edtott\u00e1k a Linux kernel 5.11.4, 5.10.21, 5.4.103, 4.19.179, 4.14.224, 4.9.260 \u00e9s 4.4.260 friss\u00edt\u00e9sekben. A kernel friss\u00edt\u00e9sei el\u00e9rhet\u0151k a Debian, Ubuntu, SUSE\/openSUSE, Arch Linux \u00e9s Fedora disztrib\u00faci\u00f3kban. A RHEL-hez az orvosi jav\u00edt\u00e1sok m\u00e9g nem ker\u00fcltek kiad\u00e1sra. <\/p>\n

A probl\u00e9ma az iscsi_host_get_param() f\u00fcggv\u00e9nyben tal\u00e1lhat\u00f3 hiba miatt alakult ki, amely a libiscsi modul r\u00e9sz\u00e9t k\u00e9pezi, \u00e9s amelyet 2006-ban vezettek be az iSCSI alrendszer fejleszt\u00e9sekor. A megfelel\u0151 m\u00e9retellen\u0151rz\u00e9sek hi\u00e1nya miatt egyes iSCSI karakterl\u00e1nc-attrib\u00fatumok, mint p\u00e9ld\u00e1ul a hostname vagy a username, meghaladhatj\u00e1k a PAGE_SIZE (4 KB) \u00e9rt\u00e9ket. A sebezhet\u0151s\u00e9g kihaszn\u00e1lhat\u00f3, ha egy nem privilegiz\u00e1lt felhaszn\u00e1l\u00f3 Netlink \u00fczeneteket k\u00fcld, amelyek az iSCSI attrib\u00fatumait a PAGE_SIZE-t meghalad\u00f3 \u00e9rt\u00e9kekre \u00e1ll\u00edtj\u00e1k. Az attrib\u00fatumok sysfs-en vagy seqfs-en kereszt\u00fcli olvas\u00e1sakor olyan k\u00f3dot h\u00edvnak meg, amely az attrib\u00fatumokat a sprintf f\u00fcggv\u00e9nyhez tov\u00e1bb\u00edtja, hogy a PAGE_SIZE-nek megfelel\u0151 m\u00e9ret\u0171 pufferbe m\u00e1solja \u0151ket. <\/p>\n

A sebezhet\u0151s\u00e9g kihaszn\u00e1l\u00e1s\u00e1nak lehet\u0151s\u00e9ge a disztrib\u00faci\u00f3kt\u00f3l f\u00fcgg, amelyek t\u00e1mogatj\u00e1k a scsi_transport_iscsi kernel modul automatikus bet\u00f6lt\u00e9s\u00e9t a NETLINK_ISCSI socket l\u00e9trehoz\u00e1s\u00e1nak k\u00eds\u00e9rlete sor\u00e1n. Azokban a disztrib\u00faci\u00f3kban, ahol ez a modul automatikusan bet\u00f6lt\u0151dik, a t\u00e1mad\u00e1s f\u00fcggetlen\u00fcl v\u00e9grehajthat\u00f3 az iSCSI funkcionalit\u00e1s haszn\u00e1lat\u00e1t\u00f3l. Sikeres exploit alkalmaz\u00e1s\u00e1hoz legal\u00e1bb egy iSCSI transport regisztr\u00e1l\u00e1sa is sz\u00fcks\u00e9ges. A transport regisztr\u00e1l\u00e1s\u00e1hoz haszn\u00e1lhat\u00f3 az ib_iser kernel modul, amely automatikusan bet\u00f6lt\u0151dik, amikor egy nem privilegiz\u00e1lt felhaszn\u00e1l\u00f3 NETLINK_RDMA socket l\u00e9trehoz\u00e1s\u00e1ra pr\u00f3b\u00e1lkozik. <\/p>\n

A sz\u00fcks\u00e9ges exploitat modulok automatikus bet\u00f6lt\u00e9se t\u00e1mogatott a CentOS 8, RHEL 8 \u00e9s Fedora eset\u00e9ben az rdma-core csomag telep\u00edt\u00e9sekor, amely n\u00e9h\u00e1ny n\u00e9pszer\u0171 csomag f\u00fcgg\u0151s\u00e9ge, \u00e9s alap\u00e9rtelmezetten telep\u00edtve van a GUI-val rendelkez\u0151 munka\u00e1llom\u00e1sok, kiszolg\u00e1l\u00f3 rendszerek \u00e9s a virtualiz\u00e1ci\u00f3s k\u00f6rnyezetek konfigur\u00e1ci\u00f3iban. Az rdma-core azonban nem ker\u00fcl telep\u00edt\u00e9sre, ha a szerver verzi\u00f3t haszn\u00e1lj\u00e1k, amely kiz\u00e1r\u00f3lag konzol m\u00f3dban m\u0171k\u00f6dik, \u00e9s a minim\u00e1lis telep\u00edt\u00e9si k\u00e9p telep\u00edt\u00e9sekor. P\u00e9ld\u00e1ul a csomag a Fedora 31 Workstation alapell\u00e1tm\u00e1ny\u00e1nak r\u00e9sze, de nem tal\u00e1lhat\u00f3 meg a Fedora 31 Server-ben. A Debian \u00e9s az Ubuntu kev\u00e9sb\u00e9 \u00e9rintettek, mivel az rdma-core csomag csak RDMA hardver megl\u00e9t\u00e9ben t\u00f6lti be a t\u00e1mad\u00e1shoz sz\u00fcks\u00e9ges kernelmodulokat.

\"A<\/center> <\/p>\n

V\u00e9delmi megold\u00e1sk\u00e9nt meg lehet tiltani a libiscsi modul automatikus bet\u00f6lt\u00e9s\u00e9t: echo \"install libiscsi \/bin\/true\" >> \/etc\/modprobe.d\/disable-libiscsi.conf <\/p>\n

Tov\u00e1bb\u00e1 az iSCSI alrendszerben k\u00e9t kev\u00e9sb\u00e9 s\u00falyos sebezhet\u0151s\u00e9get is kijav\u00edtottak, amelyek adatki\u00e1raml\u00e1shoz vezethetnek a kernelen bel\u00fcl: CVE-2021-27363 (iSCSI transport descriptor inform\u00e1ci\u00f3 sziv\u00e1rg\u00e1sa sysfs-en kereszt\u00fcl) \u00e9s CVE-2021-27364 (olvas\u00e1s a puffer hat\u00e1rain k\u00edv\u00fcli ter\u00fcletr\u0151l). Ezek a sebezhet\u0151s\u00e9gek a netlink-socketen kereszt\u00fcl t\u00f6rt\u00e9n\u0151 kapcsolattart\u00e1sra haszn\u00e1lhat\u00f3k az iSCSI alrendszerrel, an\u00e9lk\u00fcl, hogy a sz\u00fcks\u00e9ges jogosults\u00e1gokkal rendelkezn\u00e9nek. P\u00e9ld\u00e1ul egy nem privilegiz\u00e1lt felhaszn\u00e1l\u00f3 csatlakozhat az iSCSI-hoz, \u00e9s elk\u00fcldheti az \"end a session\" parancsot a session megszak\u00edt\u00e1s\u00e1ra.
\n
Forr\u00e1s: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 \u043a\u043e\u0434\u0435 \u043f\u043e\u0434\u0441\u0438\u0441\u0442\u0435\u043c\u044b iSCSI \u0438\u0437 \u0441\u043e\u0441\u0442\u0430\u0432\u0430 \u044f\u0434\u0440\u0430 Linux \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2021-27365), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u043c\u0443 \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u043a\u043e\u0434 \u043d\u0430 \u0443\u0440\u043e\u0432\u043d\u0435 \u044f\u0434\u0440\u0430 \u0438 \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c root-\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0438 \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435. \u0414\u043b\u044f \u0442\u0435\u0441\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u0434\u043e\u0441\u0442\u0443\u043f\u0435\u043d \u0440\u0430\u0431\u043e\u0447\u0438\u0439 \u043f\u0440\u043e\u0442\u043e\u0442\u0438\u043f \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430 \u0432 \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f\u0445 \u044f\u0434\u0440\u0430 Linux 5.11.4, 5.10.21, 5.4.103, 4.19.179, 4.14.224, 4.9.260 \u0438 4.4.260. \u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f \u043f\u0430\u043a\u0435\u0442\u043e\u0432 \u0441 \u044f\u0434\u0440\u043e\u043c \u0434\u043e\u0441\u0442\u0443\u043f\u043d\u044b \u0432 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 Debian, Ubuntu, SUSE\/openSUSE, […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":99422,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-99421","post","type-post","status-publish","format-standard","has-post-thumbnail","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\udd47A Linux kernel iSCSI alrendszer\u00e9nek sebezhet\u0151s\u00e9ge, amely lehet\u0151v\u00e9 teszi a privil\u00e9giumok emel\u00e9s\u00e9t | ProHoster","description":"Az iSCSI alrendszerben, amely a Linux kernel r\u00e9sze, egy sebezhet\u0151s\u00e9get (CVE-2021-27365) fedeztek fel, amely lehet\u0151v\u00e9 teszi a nem privil\u00e9giz\u00e1lt lok\u00e1lis felhaszn\u00e1l\u00f3k sz\u00e1m\u00e1ra, hogy 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