{"id":55921,"date":"2020-02-01T00:00:00","date_gmt":"2020-01-31T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/root-uyazvimost-v-sudo-zatragivayushhaya-linux-mint-i-elementary-os"},"modified":"2020-02-18T14:04:05","modified_gmt":"2020-02-18T11:04:05","slug":"root-uyazvimost-v-sudo-zatragivayushhaya-linux-mint-i-elementary-os","status":"publish","type":"post","link":"https:\/\/prohoster.info\/hu\/blog\/news\/root-uyazvimost-v-sudo-zatragivayushhaya-linux-mint-i-elementary-os","title":{"rendered":"Root-sebezhet\u0151s\u00e9g a sudo-ban, amely a Linux Mint \u00e9s az Elementary OS-t \u00e9rinti","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

A seg\u00e9dprogramban sudo<\/a><\/noindex>, amelyet arra haszn\u00e1lnak, hogy m\u00e1s felhaszn\u00e1l\u00f3k nev\u00e9ben parancsokat hajtsanak v\u00e9gre, identified<\/a><\/noindex> vulnerability (CVE-2019-18634<\/a><\/noindex>), amely lehet\u0151v\u00e9 teszi, hogy a felhaszn\u00e1l\u00f3k root jogosults\u00e1gra v\u00e1ltsanak a rendszerben. A probl\u00e9ma a sudo 1.7.1 kiad\u00e1s\u00e1val kezd\u0151dik, \u00e9s csak a \/etc\/sudoers f\u00e1jlban a \u201epwfeedback\u201d opci\u00f3 haszn\u00e1lat\u00e1val bukkan fel, amely alap\u00e9rtelmez\u00e9s szerint ki van kapcsolva, de n\u00e9h\u00e1ny disztrib\u00faci\u00f3ban, mint p\u00e9ld\u00e1ul a Linux Mint \u00e9s az Elementary OS, aktiv\u00e1lva van. A probl\u00e9ma megoldva sudo 1.8.31<\/a><\/noindex>, amelyet n\u00e9h\u00e1ny \u00f3r\u00e1val ezel\u0151tt tettek k\u00f6zz\u00e9. A disztrib\u00faci\u00f3kban a s\u00e9r\u00fcl\u00e9kenys\u00e9g egyel\u0151re jav\u00edtatlan marad.<\/p>\n

A \u201epwfeedback\u201d opci\u00f3 enged\u00e9lyezi a \u201e*\u201d karakter megjelen\u00edt\u00e9s\u00e9t minden egyes be\u00edrt karakter ut\u00e1n a jelsz\u00f3 be\u00edr\u00e1sakor. Emiatt hiba<\/a><\/noindex> a getln() f\u00fcggv\u00e9ny megval\u00f3s\u00edt\u00e1s\u00e1ban, amely a tgetpass.c f\u00e1jlban tal\u00e1lhat\u00f3, a standard bemeneten (stdin) kereszt\u00fcl megadott t\u00fal hossz\u00fa jelsz\u00f3 sor bizonyos k\u00f6r\u00fclm\u00e9nyek k\u00f6z\u00f6tt nem f\u00e9r el a lefoglalt pufferen, \u00e9s m\u00e1s adatokat \u00edrhat fel\u00fcl a veremben. A t\u00falcsordul\u00e1s a sudo k\u00f3d root jogosults\u00e1gaival t\u00f6rt\u00e9n\u0151 v\u00e9grehajt\u00e1sa sor\u00e1n l\u00e9p fel.<\/p>\n

A probl\u00e9ma l\u00e9nyege, hogy a jelsz\u00f3bevitel sor\u00e1n a ^U speci\u00e1lis karakter (sor t\u00f6rl\u00e9se) haszn\u00e1latakor \u00e9s a felv\u00e9teli m\u0171velet kudarcakor a ki\u00edrt \u201e*\u201d karakterek t\u00f6rl\u00e9s\u00e9\u00e9rt felel\u0151s k\u00f3d vissza\u00e1ll\u00edtja a rendelkez\u00e9sre \u00e1ll\u00f3 puffer m\u00e9ret\u00e9r\u0151l sz\u00f3l\u00f3 adatokat, de nem \u00e1ll\u00edtja vissza az aktu\u00e1lis poz\u00edci\u00f3ra mutat\u00f3 mutat\u00f3t a pufferben. Egy m\u00e1sik t\u00e9nyez\u0151, amely fokozza a kihaszn\u00e1l\u00e1st, az, hogy a \u201epwfeedback\u201d m\u00f3d automatikus kikapcsol\u00e1sa nem t\u00f6rt\u00e9nik meg, amikor az adatok nem termin\u00e1lon kereszt\u00fcl, hanem bemeneti folyamk\u00e9nt \u00e9rkeznek (ez a hi\u00e1nyoss\u00e1g lehet\u0151v\u00e9 teszi \u00edr\u00e1si hiba kialakul\u00e1s\u00e1t, p\u00e9ld\u00e1ul olyan rendszereken, amelyek egyir\u00e1ny\u00faak n\u00e9vtelen csatorn\u00e1kon<\/a><\/noindex> a hiba akkor l\u00e9p fel, amikor a kiolvas\u00e1s v\u00e9g\u00e9n pr\u00f3b\u00e1lkozunk \u00edrni).<\/p>\n

Mivel a t\u00e1mad\u00f3 teljes m\u00e9rt\u00e9kben ellen\u0151rzi az adatok \u00e1tkonfigur\u00e1l\u00e1s\u00e1t a veremben, nem okoz neh\u00e9zs\u00e9get olyan exploit l\u00e9trehoz\u00e1sa, amely lehet\u0151v\u00e9 teszi a root felhaszn\u00e1l\u00f3i jogosults\u00e1gok megszerz\u00e9s\u00e9t. A probl\u00e9m\u00e1t b\u00e1rmilyen felhaszn\u00e1l\u00f3 kihaszn\u00e1lhatja, f\u00fcggetlen\u00fcl a sudo haszn\u00e1lat\u00e1ra vonatkoz\u00f3 jogosults\u00e1gokt\u00f3l \u00e9s a sudoers f\u00e1jlban tal\u00e1lhat\u00f3 felhaszn\u00e1l\u00f3ra specifikus be\u00e1ll\u00edt\u00e1sokt\u00f3l. A probl\u00e9ma blokkol\u00e1s\u00e1hoz meg kell gy\u0151z\u0151dni arr\u00f3l, hogy a \/etc\/sudoers f\u00e1jlban nincs \u201epwfeedback\u201d be\u00e1ll\u00edt\u00e1s, \u00e9s ha sz\u00fcks\u00e9ges, ki kell kapcsolni (\u201eDefaults !pwfeedback\u201d). A probl\u00e9ma ellen\u0151rz\u00e9s\u00e9hez a k\u00f6vetkez\u0151 k\u00f3dot lehet futtatni:<\/p>\n

$ perl -e 'print((\u2018A\u2019 x 100 . \u2018\u2019) x 50)' | sudo -S id
\n Jelsz\u00f3: Szegment\u00e1ci\u00f3s hiba<\/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 sudo, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u043c\u043e\u0439 \u0434\u043b\u044f \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u0430\u0446\u0438\u0438 \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u043a\u043e\u043c\u0430\u043d\u0434 \u043e\u0442 \u0438\u043c\u0435\u043d\u0438 \u0434\u0440\u0443\u0433\u0438\u0445 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u0439, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2019-18634), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043f\u043e\u0432\u044b\u0441\u0438\u0442\u044c \u0441\u0432\u043e\u0438 \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0438 \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435 \u0434\u043e \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f root. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u043d\u0430\u0447\u0438\u043d\u0430\u044f \u0441 \u0432\u044b\u043f\u0443\u0441\u043a\u0430 sudo 1.7.1 \u0442\u043e\u043b\u044c\u043a\u043e \u043f\u0440\u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0438 \u0432 \u0444\u0430\u0439\u043b\u0435 \/etc\/sudoers \u043e\u043f\u0446\u0438\u0438 «pwfeedback», \u043a\u043e\u0442\u043e\u0440\u0430\u044f \u043e\u0442\u043a\u043b\u044e\u0447\u0435\u043d\u0430 \u043f\u043e \u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e, \u043d\u043e \u0430\u043a\u0442\u0438\u0432\u0438\u0440\u043e\u0432\u0430\u043d\u0430 \u0432 \u043d\u0435\u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445, \u0442\u0430\u043a\u0438\u0445 \u043a\u0430\u043a Linux Mint \u0438 Elementary OS. […]<\/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-55921","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\udd47Root-sebezhet\u0151s\u00e9g a sud\u00f3ban, amely \u00e9rinti a Linux Mintet \u00e9s az Elementary OS-t | ProHoster","description":"A sudo seg\u00e9dprogram, amelyet m\u00e1s felhaszn\u00e1l\u00f3k nev\u00e9ben v\u00e9grehajtott parancsok szervez\u00e9s\u00e9re 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