{"id":82655,"date":"2020-05-23T19:42:11","date_gmt":"2020-05-23T17:42:11","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/checkpoint-predlozhil-tehniku-zashhity-safe-linking-uslozhnyayushhuyu-ekspluatacziyu-uyazvimostej"},"modified":"2020-05-23T19:42:11","modified_gmt":"2020-05-23T17:42:11","slug":"checkpoint-predlozhil-tehniku-zashhity-safe-linking-uslozhnyayushhuyu-ekspluatacziyu-uyazvimostej","status":"publish","type":"post","link":"https:\/\/prohoster.info\/hu\/blog\/news\/checkpoint-predlozhil-tehniku-zashhity-safe-linking-uslozhnyayushhuyu-ekspluatacziyu-uyazvimostej","title":{"rendered":"A Google Blog Szerkeszt\u0151j\u00e9t\u0151l: \u00c9rdekelte valaha, hogy a Google Cloud Technical Solutions (TSE) m\u00e9rn\u00f6kei hogyan kezelik a t\u00e1mogat\u00f3 k\u00e9rd\u00e9seit?","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Checkpoint c\u00e9ge bemutatta<\/a><\/noindex> A Safe-Linking v\u00e9delmi mechanizmus, amely megnehez\u00edti a kihaszn\u00e1l\u00e1sok l\u00e9trehoz\u00e1s\u00e1t, amelyek manipul\u00e1lj\u00e1k a malloc h\u00edv\u00e1s sor\u00e1n allok\u00e1lt pufferek c\u00edmeinek meghat\u00e1roz\u00e1s\u00e1t vagy megv\u00e1ltoztat\u00e1s\u00e1t. A Safe-Linking nem z\u00e1rja ki teljesen a sebezhet\u0151s\u00e9gek kihaszn\u00e1l\u00e1s\u00e1nak lehet\u0151s\u00e9g\u00e9t, de minim\u00e1lis k\u00f6lts\u00e9gekkel jelent\u0151sen megnehez\u00edti bizonyos kateg\u00f3ri\u00e1j\u00fa kihaszn\u00e1l\u00e1sok l\u00e9trehoz\u00e1s\u00e1t, mivel a kihaszn\u00e1lhat\u00f3 puffert\u00falcsordul\u00e1s mellett tov\u00e1bbi sebezhet\u0151s\u00e9get is meg kell tal\u00e1lni, amely inform\u00e1ci\u00f3sziv\u00e1rg\u00e1st id\u00e9z el\u0151 a mem\u00f3riahalom elhelyez\u00e9s\u00e9r\u0151l.<\/p>\n

A Safe-Linking megval\u00f3s\u00edt\u00e1s\u00e1val k\u00e9sz\u00fclt jav\u00edt\u00e1sok el\u00e9rhet\u0151k Glibc (ptmalloc), uClibc-NG (dlmalloc), gperftools (tcmalloc) \u00e9s Google TCMalloc sz\u00e1m\u00e1ra, valamint a Chromium v\u00e9delem friss\u00edt\u00e9s\u00e9re is javasolt\u00e1k.
\nA Chromiumba 2012 \u00f3ta be\u00e9p\u00edtve van egy megold\u00e1s ugyanarra a probl\u00e9m\u00e1ra, a MaskPtr v\u00e9delmi technika, de a Checkpoint megold\u00e1sa magasabb teljes\u00edtm\u00e9nyt mutat.
\nA javasolt jav\u00edt\u00e1sokat m\u00e1r j\u00f3v\u00e1hagyt\u00e1k az augusztusi kiad\u00e1sra Glibc 3.32<\/a><\/noindex> \u00e9s a Safe-Linking alkalmaz\u00e1sa alap\u00e9rtelmez\u00e9s szerint be fog ker\u00fclni. Az uClibc-NG a Safe-Linkinget a Time magazin \u201e2018 legjobb 25 fot\u00f3k\u00f6nyve\u201d k\u00f6z\u00e9 ker\u00fclt.<\/a><\/noindex> az 1.0.33 verzi\u00f3ba fogja integr\u00e1lni, \u00e9s alap\u00e9rtelmez\u00e9s szerint be van kapcsolva. A gperftools (r\u00e9gi tcmalloc) v\u00e1ltoztat\u00e1sa elfogadva<\/a><\/noindex>, de a j\u00f6v\u0151beli kiad\u00e1sok egyik\u00e9ben opci\u00f3k\u00e9nt javasolj\u00e1k. <\/p>\n

Fejleszt\u0151k TCMalloc<\/a><\/noindex> (\u00faj tcmalloc) elutas\u00edtotta a befogad\u00e1st v\u00e1ltoz\u00e1s<\/a><\/noindex>, hivatkozva a teljes\u00edtm\u00e9ny jelent\u0151s cs\u00f6kken\u00e9s\u00e9re \u00e9s a sz\u00fcks\u00e9gess\u00e9g\u00e9re, hogy kiterjesztett teszteket v\u00e9gezzenek a rendszer rendszeres ellen\u0151rz\u00e9s\u00e9re. A Checkpoint m\u00e9rn\u00f6kei \u00e1ltal v\u00e9gzett tesztel\u00e9s azt mutatta, hogy a Safe-Linking m\u00f3dszer nem okoz extra mem\u00f3riak\u00f6lt\u00e9st, \u00e9s a teljes\u00edtm\u00e9ny az adathalmoz\u00e1ssal v\u00e9gzett m\u0171veletek sor\u00e1n \u00e1tlagosan csak 0,02%-kal cs\u00f6kken, a legrosszabb esetben pedig 1,5%-kal (\u00f6sszehasonl\u00edt\u00e1sk\u00e9ppen a Chromium m\u00f3dszer\u00e9nek k\u00f6lts\u00e9geit \u201e2%-n\u00e1l kevesebbnek\u201d \u00e9rt\u00e9kelik). A bekapcsol\u00e1s
\nminden free() h\u00edv\u00e1sn\u00e1l 2-3 tov\u00e1bbi assembler utas\u00edt\u00e1st \u00e9s malloc() h\u00edv\u00e1sn\u00e1l 3-4 utas\u00edt\u00e1st ig\u00e9nyel. Az inicializ\u00e1l\u00f3 \u00e9s v\u00e9letlensz\u00e1m-gener\u00e1l\u00f3 f\u00e1zisok futtat\u00e1s\u00e1ra nincs sz\u00fcks\u00e9g.<\/p>\n

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

A Safe-Linking nemcsak a k\u00fcl\u00f6nb\u00f6z\u0151 halom (heap) megval\u00f3s\u00edt\u00e1sok biztons\u00e1g\u00e1nak n\u00f6vel\u00e9s\u00e9re alkalmazhat\u00f3, hanem integrit\u00e1sellen\u0151rz\u0151 eszk\u00f6z\u00f6k hozz\u00e1ad\u00e1s\u00e1ra is b\u00e1rmely adatszerkezethez, ahol egyir\u00e1ny\u00fa mutat\u00f3k list\u00e1it helyezik el k\u00f6zvetlen\u00fcl a pufferek mellett. A m\u00f3dszer nagyon egyszer\u0171en megval\u00f3s\u00edthat\u00f3, \u00e9s csup\u00e1n egy makr\u00f3 hozz\u00e1ad\u00e1s\u00e1t ig\u00e9nyli, valamint annak alkalmaz\u00e1s\u00e1t a k\u00f6vetkez\u0151 blokkra mutat\u00f3 mutat\u00f3kra a k\u00f3dban (p\u00e9ld\u00e1ul a Glibc-hez) v\u00e1ltozik<\/a><\/noindex> mind\u00f6ssze n\u00e9h\u00e1ny sor a k\u00f3dban). A m\u00f3dszer a k\u00f6vetkez\u0151 m\u00f3dos\u00edt\u00e1sokra korl\u00e1toz\u00f3dik:<\/p>\n

+#define PROTECT_PTR(pos, ptr) \\
\n ((__typeof (ptr)) ((((size_t) pos) >> 12) ^ ((size_t) ptr)))<\/p>\n

+#define REVEAL_PTR(ptr) PROTECT_PTR (&ptr, ptr)<\/p>\n

\u2014 nextp = p->fd;
\n + nextp = REVEAL_PTR (p->fd);
\n …<\/p>\n

A m\u00f3dszer l\u00e9nyege, hogy v\u00e9letlenszer\u0171 adatokat alkalmaz az ASLR c\u00edmragaszt\u00e1si mechanizmus\u00e1b\u00f3l (mmap_base) az egyl\u00e1nc\u00fa list\u00e1k, mint a Fast-Bins \u00e9s TCache v\u00e9delm\u00e9re. Miel\u0151tt a list\u00e1ban a k\u00f6vetkez\u0151 elemre mutat\u00f3 mutat\u00f3 \u00e9rt\u00e9k\u00e9re alkalmazn\u00e1k, maszk \u00e1talak\u00edt\u00e1st \u00e9s mem\u00f3riaoldali igaz\u00edt\u00e1st v\u00e9geznek. A mutat\u00f3 a \u201e(L >> PAGE_SHIFT) XOR (P)\u201d m\u0171velet eredm\u00e9ny\u00e9re cser\u00e9l\u0151dik, ahol P a mutat\u00f3 \u00e9rt\u00e9ke, L pedig az a mem\u00f3riahely, ahol ez a mutat\u00f3 t\u00e1rolva van.
\n

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

A rendszerben t\u00f6rt\u00e9n\u0151 haszn\u00e1latkor ASLR<\/a><\/noindex> (Address Space Layout Randomization) a halom alapc\u00edm\u00e9vel egybees\u0151 L bitjei v\u00e9letlenszer\u0171 \u00e9rt\u00e9keket tartalmaznak, amelyek kulcsk\u00e9nt szolg\u00e1lnak P k\u00f3dol\u00e1s\u00e1hoz (12 bites elmozd\u00edt\u00e1ssal nyerik ki 4096 b\u00e1jtos oldalak eset\u00e9n). Az ilyen manipul\u00e1ci\u00f3 cs\u00f6kkenti a mutat\u00f3 elkap\u00e1s\u00e1nak kock\u00e1zat\u00e1t egy exploitban, mivel a mutat\u00f3 nem t\u00e1rol\u00f3dik a kezdeti form\u00e1j\u00e1ban, \u00e9s ahhoz, hogy azt helyettes\u00edteni lehessen, tudni kell a halom elhelyezked\u00e9s\u00e9re vonatkoz\u00f3 inform\u00e1ci\u00f3kat. Ezenk\u00edv\u00fcl a patch k\u00f3dj\u00e1ban egy tov\u00e1bbi blokk igaz\u00edt\u00e1si ellen\u0151rz\u00e9s is szerepel, amely megakad\u00e1lyozza a t\u00e1mad\u00f3kat abban, hogy a mutat\u00f3t nem igaz\u00edtott \u00e9rt\u00e9kre cser\u00e9lj\u00e9k, \u00e9s ismerni\u00fck kell, h\u00e1ny bitet haszn\u00e1ltak az igaz\u00edt\u00e1shoz; ez a 64 bites rendszereken tov\u00e1bbi 15-b\u0151l 16 t\u00e1mad\u00e1si k\u00eds\u00e9rlet blokkol\u00e1s\u00e1t teszi lehet\u0151v\u00e9, figyelembe v\u00e9ve az igaz\u00edt\u00e1st.<\/p>\n

A m\u00f3dszer hat\u00e9kony a mutat\u00f3k r\u00e9szleges fel\u00fcl\u00edr\u00e1s\u00e1ra (az als\u00f3 b\u00e1jtok megv\u00e1ltoztat\u00e1sa), a mutat\u00f3k teljes \u00fajra\u00edr\u00e1s\u00e1ra (a t\u00e1mad\u00f3 k\u00f3dj\u00e1ra ir\u00e1ny\u00edt\u00e1s) \u00e9s az lista poz\u00edci\u00f3j\u00e1nak nem igaz\u00edtott c\u00edmen t\u00f6rt\u00e9n\u0151 megv\u00e1ltoztat\u00e1s\u00e1ra ir\u00e1nyul\u00f3 t\u00e1mad\u00e1sokkal szemben. P\u00e9ldak\u00e9nt bemutatj\u00e1k, hogy a Safe-Linking alkalmaz\u00e1sa a malloc-ban megakad\u00e1lyozn\u00e1 a nemr\u00e9giben felt\u00e1rt<\/a><\/noindex> ugyanazok a kutat\u00f3k a sebezhet\u0151s\u00e9gekr\u0151l CVE-2020-6007<\/a><\/noindex> a Philips Hue Bridge intelligens vil\u00e1g\u00edt\u00e1s\u00e1ban, amelyet a pufferm\u00e9ret t\u00fall\u00e9p\u00e9se okoz, \u00e9s lehet\u0151v\u00e9 teszi az eszk\u00f6z feletti ir\u00e1ny\u00edt\u00e1st.<\/p>\n

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

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

\u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Checkpoint \u043f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u0438\u043b\u0430 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c \u0437\u0430\u0449\u0438\u0442\u044b Safe-Linking, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0438\u0439 \u0443\u0441\u043b\u043e\u0436\u043d\u0438\u0442\u044c \u0441\u043e\u0437\u0434\u0430\u043d\u0438\u0435 \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u043e\u0432, \u043c\u0430\u043d\u0438\u043f\u0443\u043b\u0438\u0440\u0443\u044e\u0449\u0438\u0445 \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0435\u043d\u0438\u0435\u043c \u0438\u043b\u0438 \u0438\u0437\u043c\u0435\u043d\u0435\u043d\u0438\u0435\u043c \u0443\u043a\u0430\u0437\u0430\u0442\u0435\u043b\u0435\u0439 \u043d\u0430 \u0431\u0443\u0444\u0435\u0440\u044b, \u0432\u044b\u0434\u0435\u043b\u0435\u043d\u043d\u044b\u0435 \u043f\u0440\u0438 \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0438 \u0432\u044b\u0437\u043e\u0432\u0430 malloc. Safe-Linking \u043f\u043e\u043b\u043d\u043e\u0441\u0442\u044c\u044e \u043d\u0435 \u0431\u043b\u043e\u043a\u0438\u0440\u0443\u0435\u0442 \u0432\u043e\u0437\u043c\u043e\u0436\u043d\u043e\u0441\u0442\u044c \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0435\u0439, \u043d\u043e \u043f\u0440\u0438 \u043c\u0438\u043d\u0438\u043c\u0430\u043b\u044c\u043d\u044b\u0445 \u043d\u0430\u043a\u043b\u0430\u0434\u043d\u044b\u0445 \u0440\u0430\u0441\u0445\u043e\u0434\u0430\u0445 \u0441\u0443\u0449\u0435\u0441\u0442\u0432\u0435\u043d\u043d\u043e \u0443\u0441\u043b\u043e\u0436\u043d\u044f\u0435\u0442 \u0441\u043e\u0437\u0434\u0430\u043d\u0438\u0435 \u043d\u0435\u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u043a\u0430\u0442\u0435\u0433\u043e\u0440\u0438\u0439 \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u043e\u0432, \u0442\u0430\u043a \u043a\u0430\u043a \u043f\u043e\u043c\u0438\u043c\u043e \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0438\u0440\u0443\u0435\u043c\u043e\u0433\u043e \u043f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u0431\u0443\u0444\u0435\u0440\u0430 \u043d\u0435\u043e\u0431\u0445\u043e\u0434\u0438\u043c\u043e \u043d\u0430\u0439\u0442\u0438 \u0435\u0449\u0451 \u043e\u0434\u043d\u0443 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, \u0432\u044b\u0437\u044b\u0432\u0430\u044e\u0449\u0443\u044e \u0443\u0442\u0435\u0447\u043a\u0443 \u0441\u0432\u0435\u0434\u0435\u043d\u0438\u0439 \u043e […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":82656,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-82655","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 Checkpoint bemutatott egy Safe-Linking v\u00e9delmi technik\u00e1t, amely megnehez\u00edti a sebezhet\u0151s\u00e9gek kihaszn\u00e1l\u00e1s\u00e1t | ProHoster","description":"A Checkpoint bemutatta a Safe-Linking v\u00e9delmi 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