{"id":101245,"date":"2021-09-10T22:22:37","date_gmt":"2021-09-10T20:22:37","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-ghostscript-ekspluatiruemaya-cherez-imagemagick"},"modified":"2021-09-10T22:22:37","modified_gmt":"2021-09-10T20:22:37","slug":"uyazvimost-v-ghostscript-ekspluatiruemaya-cherez-imagemagick","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sl\/blog\/news\/uyazvimost-v-ghostscript-ekspluatiruemaya-cherez-imagemagick","title":{"rendered":"Ranljivost v Ghostscript, izkori\u0161\u010dena preko ImageMagick","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V Ghostscriptu, orodju za obdelavo, pretvarjanje in ustvarjanje dokumentov v formatih PostScript in PDF, je bila odkita kriti\u010dna ranljivost (CVE-2021-3781), ki omogo\u010da izvajanje poljubne kode pri obdelavi specializiranega dokumenta. Na te\u017eavo je prvi opozoril Emil Lerner, ki je o ranljivosti spregovoril 25. avgusta na konferenci ZeroNights X v Sankt Peterburgu (v predavanju je opisal, kako je Emil v okviru programov bug bounty izkoristil ranljivost za pridobitev nagrad, ko je izvajal napade na storitve AirBNB, Dropbox in Yandex.Nedvestnost). <\/p>\n

5. septembra je bil v javnosti objavljen delujo\u010d eksploitat, ki omogo\u010da napade na sisteme z Ubuntu 20.04 preko prenosa specializiranega dokumenta, ki se predstavlja kot slika, web skriptu, ki uporablja paket php-imagemagick. Po prvih podatkih naj bi bil tak eksploitat v obtoku \u017ee od marca. Omenjali so mo\u017enost napada na sisteme z GhostScript 9.50, vendar se je izkazalo, da se ranljivost pojavlja tudi v vseh subsequentnih razli\u010dicah GhostScript, vklju\u010dno z razli\u010dico 9.55, ki je v razvoju v Gitu. <\/p>\n

Popravilo je bilo predlagano 8. septembra in po recenziji sprejeto v repozitorij GhostScript 9. septembra. V mnogih distribucijah te\u017eava ostaja \u0161e vedno nepora\u010dunana (status objave posodobitev si lahko ogledate na straneh Debian, Ubuntu, Fedora, SUSE, RHEL, Arch Linux, FreeBSD, NetBSD). Izid GhostScript z odpravljeno ranljivostjo na\u010drtujejo objaviti do konca meseca. <\/p>\n

Te\u017eava je posledica mo\u017enosti zaobvoda izolacijskega na\u010dina «-dSAFER» zaradi nezadostne preverjanja parametrov Postscript naprave «%pipe%», kar je omogo\u010dilo izvajanje poljubnih shell ukazov. Na primer, za zagon orodja id v dokumentu je dovolj, da navedete vrstico «(%pipe%\/tmp\/&id)(w)file» ali «(%pipe%\/tmp\/;id)(r)file». <\/p>\n

Pripomnimo, da so ranljivosti v Ghostscript posebej nevarne, saj se ta paket uporablja v mnogih priljubljenih aplikacijah za obdelavo formatov PostScript in PDF. Na primer, Ghostscript je vklju\u010den v proces ustvarjanja miniatur na namizju, pri indeksiranju podatkov v ozadju ter pri pretvorbi slik. Za uspe\u0161en napad je v mnogih primerih dovolj, da preprosto nalo\u017eite datoteko z izkori\u0161\u010danjem ali si ogledate katalog z njo v upravitelju datotek, ki podpira prikazovanje miniatur dokumentov, kot je Nautilus. <\/p>\n

Ranljivosti v Ghostscript je mogo\u010de izkoristiti tudi prek obdelovalnikov slik, ki temeljijo na paketih ImageMagick in GraphicsMagick, tako da jim posredujete JPEG ali PNG datoteko, v kateri je namesto slike koda PostScript (tak\u0161na datoteka bo obdelana v Ghostscript, saj MIME-tip prepozna po vsebini in ne zana\u0161a na kon\u010dnico).
\n
Izvor: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 Ghostscript, \u043d\u0430\u0431\u043e\u0440\u0435 \u0438\u043d\u0441\u0442\u0440\u0443\u043c\u0435\u043d\u0442\u043e\u0432 \u0434\u043b\u044f \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0438, \u043f\u0440\u0435\u043e\u0431\u0440\u0430\u0437\u043e\u0432\u0430\u043d\u0438\u044f \u0438 \u0433\u0435\u043d\u0435\u0440\u0430\u0446\u0438\u0438 \u0434\u043e\u043a\u0443\u043c\u0435\u043d\u0442\u043e\u0432 \u0432 \u0444\u043e\u0440\u043c\u0430\u0442\u0430\u0445 PostScript \u0438 PDF, \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-2021-3781), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u043b\u044c\u043d\u044b\u0439 \u043a\u043e\u0434 \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u043e\u0433\u043e \u0444\u0430\u0439\u043b\u0430. \u0418\u0437\u043d\u0430\u0447\u0430\u043b\u044c\u043d\u043e \u043d\u0430 \u043d\u0430\u043b\u0438\u0447\u0438\u0435 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u043e\u0431\u0440\u0430\u0442\u0438\u043b \u0432\u043d\u0438\u043c\u0430\u043d\u0438\u0435 \u042d\u043c\u0438\u043b\u044c \u041b\u0435\u0440\u043d\u0435\u0440, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u0440\u0430\u0441\u0441\u043a\u0430\u0437\u0430\u043b \u043e\u0431 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 25 \u0430\u0432\u0433\u0443\u0441\u0442\u0430 \u043d\u0430 \u043f\u0440\u043e\u0448\u0435\u0434\u0448\u0435\u0439 \u0432 \u0421\u0430\u043d\u043a\u0442-\u041f\u0435\u0442\u0435\u0440\u0431\u0443\u0440\u0433\u0435 \u043a\u043e\u043d\u0444\u0435\u0440\u0435\u043d\u0446\u0438\u0438 ZeroNights X (\u0432 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\u0438\u043d\u0441\u0442\u0440\u0443\u043c\u0435\u043d\u0442\u043e\u0432 \u0434\u043b\u044f \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0438, \u043f\u0440\u0435\u043e\u0431\u0440\u0430\u0437\u043e\u0432\u0430\u043d\u0438\u044f \u0438 \u0433\u0435\u043d\u0435\u0440\u0430\u0446\u0438\u0438 \u0434\u043e\u043a\u0443\u043c\u0435\u043d\u0442\u043e\u0432 \u0432 \u0444\u043e\u0440\u043c\u0430\u0442\u0430\u0445 PostScript \u0438 PDF, \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-2021-3781), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u043b\u044c\u043d\u044b\u0439 \u043a\u043e\u0434 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