{"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\/en\/blog\/news\/uyazvimost-v-e2fsck-proyavlyayushhayasya-pri-obrabotke-spetsialno-oformlennyh-katalogov","title":{"rendered":"A vulnerability in e2fsck, manifested when processing specially crafted directories.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

In the e2fsck utility included with the package e2fsprogs<\/a><\/noindex>, identified<\/a><\/noindex> vulnerability<\/a><\/noindex> (CVE-2019-5188<\/a><\/noindex>), allows an attacker to execute code during the file system check of directories that are specially crafted. The vulnerability has been confirmed in versions from 1.43.3 to 1.45.4. The vulnerability has been fixed in the update e2fsck 1.45.5<\/a><\/noindex>. In the distributions, the issue remains unresolved (Debian<\/a><\/noindex>, Arch Linux<\/a><\/noindex>, Arch<\/a><\/noindex>, Ubuntu<\/a><\/noindex>, SUSE\/openSUSE<\/a><\/noindex>).<\/p>\n

The vulnerability is caused by a flaw in the mutate_name() function from the rehash.c file, which is used when reconstructing hash tables related to directories that map all files within them. Corruption of the directory-related hash_entry structure may allow an attacker to write data outside the allocated buffer. When multiple files with the same name are found in the directory's hash table, the e2fsck utility renames the duplicate files by appending ~0, ~1, etc., to their names. For temporarily storing the new name during such renaming, a buffer of size 256 bytes is allocated on the stack. <\/p>\n

The size of the copied data is determined by the expression «entry->name_len & 0xff», but the value of entry->name_len is loaded from the structure on disk, rather than being calculated based on the actual size of the name. If the size is zero, the array index takes the value -1, creating conditions for integer underflow and overwriting other data on the stack with the value «~0». For 64-bit systems, exploitation of the vulnerability is deemed unlikely and requires no stack size restrictions (ulimit -s unlimited). For 32-bit systems, exploitation is considered possible, but the outcome heavily depends on how the executable file was compiled.<\/p>\n

To carry out an attack, an attacker needs to corrupt data in a section with an ext2, ext3, or ext4 file system. Since this operation requires superuser privileges, the vulnerability poses a threat when the e2fsck utility checks external drives or filesystem images obtained from external sources.<\/p>\n

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

Source: 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 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\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432\u044b\u0437\u0432\u0430\u043d\u0430 […]<\/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-55016","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\udd47Vulnerability in e2fsck, manifesting when processing specially crafted directories | ProHoster","description":"In the e2fsck utility included with the e2fsprogs 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