{"id":55016,"date":"2020-01-10T00:00:00","date_gmt":"2020-01-09T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/uyazvimost-v-e2fsck-proyavlyayushhayasya-pri-obrabotke-spetsialno-oformlennyh-katalogov"},"modified":"2020-02-18T14:03:05","modified_gmt":"2020-02-18T11:03:05","slug":"uyazvimost-v-e2fsck-proyavlyayushhayasya-pri-obrabotke-spetsialno-oformlennyh-katalogov","status":"publish","type":"post","link":"https:\/\/prohoster.info\/hu\/blog\/news\/uyazvimost-v-e2fsck-proyavlyayushhayasya-pri-obrabotke-spetsialno-oformlennyh-katalogov","title":{"rendered":"Sebezhet\u0151s\u00e9g az e2fsck-ban, amely speci\u00e1lisan kialak\u00edtott k\u00f6nyvt\u00e1rak feldolgoz\u00e1sa sor\u00e1n jelentkezik","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Az e2fsck seg\u00e9dprogramban, amely az e2fsprogs csomag r\u00e9szek\u00e9nt \u00e9rkezik e2fsprogs<\/a><\/noindex>, identified<\/a><\/noindex> vulnerability<\/a><\/noindex> (CVE-2019-5188<\/a><\/noindex>), amely lehet\u0151v\u00e9 teszi a rosszindulat\u00fa k\u00f3d v\u00e9grehajt\u00e1s\u00e1t a f\u00e1jlrendszer ellen\u0151rz\u00e9se sor\u00e1n, amely speci\u00e1lisan kialak\u00edtott k\u00f6nyvt\u00e1rakat tartalmaz. A sebezhet\u0151s\u00e9g az 1.43.3 \u00e9s 1.45.4 k\u00f6z\u00f6tti verzi\u00f3kban meger\u0151s\u00edtett. A sebezhet\u0151s\u00e9get az e2fsck 1.45.5<\/a><\/noindex>. A disztrib\u00faci\u00f3kban a probl\u00e9ma tov\u00e1bbra is megoldatlan (Debian<\/a><\/noindex>, Arch Linux<\/a><\/noindex>, SUSE\/openSUSE<\/a><\/noindex>, Ubuntu<\/a><\/noindex>, RHEL<\/a><\/noindex>).<\/p>\n

A sebezhet\u0151s\u00e9g a rehash.c f\u00e1jlban tal\u00e1lhat\u00f3 mutate_name() funkci\u00f3 hib\u00e1j\u00e1b\u00f3l ered, amely a k\u00f6nyvt\u00e1rhoz kapcsol\u00f3d\u00f3 hash-t\u00e1bl\u00e1k \u00fajraintegr\u00e1l\u00e1sakor alkalmaz\u00f3dik, biztos\u00edtva a k\u00f6nyvt\u00e1rhoz tartoz\u00f3 \u00f6sszes f\u00e1jl illeszt\u00e9s\u00e9t. A k\u00f6nyvt\u00e1rhoz kapcsol\u00f3d\u00f3 hash_entry strukt\u00fara s\u00e9r\u00fcl\u00e9se lehet\u0151v\u00e9 teheti a t\u00e1mad\u00f3 adatainak \u00edr\u00e1s\u00e1t a lefoglalt puffert\u0151l k\u00edv\u00fcli ter\u00fcletre. Ha a hash-t\u00e1bl\u00e1ban a k\u00f6nyvt\u00e1rhoz t\u00f6bb f\u00e1jl is t\u00e1rsul azonos n\u00e9vvel, az e2fsck seg\u00e9dprogram \u00e1tnevezi a duplik\u00e1lt f\u00e1jlokat, hozz\u00e1f\u0171zve a n\u00e9vhez ~0, ~1 stb. A f\u00e1jl \u00e1tnevez\u00e9se sor\u00e1n egy 256 b\u00e1jtos puffert foglalnak le a veremben az \u00faj n\u00e9v ideiglenes t\u00e1rol\u00e1s\u00e1ra. <\/p>\n

A m\u00e1solt adatok m\u00e9rete az «entry->name_len & 0xff» kifejez\u00e9s hat\u00e1rozza meg, de az entry->name_len \u00e9rt\u00e9ke a lemez strukt\u00far\u00e1j\u00e1b\u00f3l t\u00f6lt\u0151dik be, nem pedig a t\u00e9nyleges n\u00e9v m\u00e9rete alapj\u00e1n sz\u00e1m\u00edt\u00f3dik. Ha a m\u00e9ret nulla, akkor a t\u00f6mb indexe -1 \u00e9rt\u00e9ket vesz fel, \u00e9s lehet\u0151s\u00e9gek teremt\u0151dnek a s\u00e9r\u00fcl\u00e9kenys\u00e9g kihaszn\u00e1l\u00e1s\u00e1ra az als\u00f3 hat\u00e1ron val\u00f3 sz\u00e1m\u00e9rt\u00e9k alulfoly\u00e1sa (integer underflow) r\u00e9v\u00e9n, amely m\u00e1s adatokat \u00edrhat fel\u00fcl a veremben a «~0» \u00e9rt\u00e9kkel. 64 bites rendszerek eset\u00e9n a s\u00e9r\u00fcl\u00e9kenys\u00e9g kihaszn\u00e1l\u00e1sa val\u00f3sz\u00edn\u0171tlennek \u00edt\u00e9lhet\u0151, \u00e9s a verem m\u00e9ret\u00e9re vonatkoz\u00f3 korl\u00e1toz\u00e1sok hi\u00e1ny\u00e1t ig\u00e9nyli (ulimit -s unlimited). 32 bites rendszerek eset\u00e9n a kihaszn\u00e1l\u00e1s lehets\u00e9ges, de az eredm\u00e9ny nagym\u00e9rt\u00e9kben f\u00fcgg att\u00f3l, hogy a futtathat\u00f3 f\u00e1jlt hogyan \u00e1ll\u00edtotta \u00f6ssze a ford\u00edt\u00f3.<\/p>\n

A t\u00e1mad\u00e1s v\u00e9grehajt\u00e1s\u00e1hoz a t\u00e1mad\u00f3nak k\u00fcl\u00f6nf\u00e9lek\u00e9ppen kell megs\u00e9rtenie az ext2, ext3 vagy ext4 f\u00e1jlrendszer adatait. Mivel ez a m\u0171velet root jogosults\u00e1gokat ig\u00e9nyel, a sebezhet\u0151s\u00e9g fenyeget\u00e9st jelent az e2fsck seg\u00e9dprogram \u00e1ltal ellen\u0151rz\u00f6tt k\u00fcls\u0151 t\u00e1rol\u00f3k vagy a k\u00fcls\u0151 forr\u00e1sb\u00f3l sz\u00e1rmaz\u00f3 f\u00e1jlrendszer k\u00e9pek ellen\u0151rz\u00e9sekor.<\/p>\n

<\/a><\/noindex><\/p>\n

Forr\u00e1s: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 \u0443\u0442\u0438\u043b\u0438\u0442\u0435 e2fsck, \u043f\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u043c\u043e\u0439 \u0432 \u0441\u043e\u0441\u0442\u0430\u0432\u0435 \u043f\u0430\u043a\u0435\u0442\u0430 e2fsprogs, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2019-5188), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0434\u043e\u0431\u0438\u0442\u044c\u0441\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u043a\u043e\u0434\u0430 \u0437\u043b\u043e\u0443\u043c\u044b\u0448\u043b\u0435\u043d\u043d\u0438\u043a\u0430 \u043f\u0440\u0438 \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0438 \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0438 \u0444\u0430\u0439\u043b\u043e\u0432\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b, \u0441\u043e\u0434\u0435\u0440\u0436\u0430\u0449\u0435\u0439 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u044b\u043c \u043e\u0431\u0440\u0430\u0437\u043e\u043c \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u0435 \u043a\u0430\u0442\u0430\u043b\u043e\u0433\u0438. \u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u043e \u0432 \u0432\u044b\u043f\u0443\u0441\u043a\u0430\u0445 \u0441 1.43.3 \u043f\u043e 1.45.4. \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\u0438 e2fsck 1.45.5. \u0412 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u043e\u043a\u0430 \u043e\u0441\u0442\u0430\u0451\u0442\u0441\u044f \u043d\u0435\u0438\u0441\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u043d\u043e\u0439 (Debian, Arch Linux, SUSE\/openSUSE, Ubuntu, RHEL). 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