{"id":101551,"date":"2021-10-06T04:22:36","date_gmt":"2021-10-06T02:22:36","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-http-servere-apache-2-4-49-pozvolyayushhaya-poluchit-fajly-vne-kornya-sajta"},"modified":"2021-10-06T04:22:36","modified_gmt":"2021-10-06T02:22:36","slug":"uyazvimost-v-http-servere-apache-2-4-49-pozvolyayushhaya-poluchit-fajly-vne-kornya-sajta","status":"publish","type":"post","link":"https:\/\/prohoster.info\/pl\/blog\/news\/uyazvimost-v-http-servere-apache-2-4-49-pozvolyayushhaya-poluchit-fajly-vne-kornya-sajta","title":{"rendered":"Vulnerability in Apache http server 2.4.49 allowing access to files outside the website root","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"
An emergency update has been released for Apache http server 2.4.50, which fixes an actively exploited 0-day vulnerability (CVE-2021-41773) that allows access to files from areas outside the web root directory. This vulnerability enables arbitrary system files and web script source codes, readable by the user under which the http server is running, to be uploaded. Developers were notified of the problem on September 17, but could only release the update today after cases of the vulnerability being used to attack websites were recorded online. <\/p>\n
The danger of the vulnerability is somewhat mitigated by the fact that the issue only appears in the recently released version 2.4.49 and does not affect all earlier releases. Stable branches of conservative server distributions have not yet used the 2.4.49 release (Debian, RHEL, Ubuntu, SUSE), but the problem has affected continuously updated distributions such as Fedora, Arch Linux, and Gentoo, as well as FreeBSD ports. <\/p>\n
Vulnerability is caused by an error made during the code refactoring for normalizing paths in the URI, which resulted in the encoded character for the dot in the path not being normalized if preceded by another dot. This allowed the injection of unfiltered characters \u2018.. \/\u2019 into the resulting path by specifying the sequence \u2018. \/\u2019 in the request. For example, a request like \u2018https:\/\/example.com\/cgi-bin\/.\/.\/.\/.\/etc\/passwd\u2019 or \u2018https:\/\/example.com\/cgi-bin\/.\/\/\/\/etc\/hosts\u2019 allowed access to the content of the file \u2018\/etc\/passwd\u2019. <\/p>\n
The problem does not occur if access to directories is explicitly denied using the setting \u2018require all denied\u2019. For partial protection, you can specify in the configuration file: require all denied <\/p>\n
In Apache httpd version 2.4.50, another vulnerability (CVE-2021-41524) affecting the module implementing the HTTP\/2 protocol has also been fixed. This vulnerability allowed sending specially crafted requests to trigger a null pointer dereference and crash the process. This vulnerability also only manifests in version 2.4.49. As a workaround for protection, you can disable HTTP\/2 support. \n \u0179r\u00f3d\u0142o: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"