Unrestricted file upload

A file upload vulnerability exists in ukcms v1.1.7 and earlier. The vulnerability is due to the system not strictly filtering the file upload type. An attacker can exploit the vulnerability to upload a script Trojan to admin.php/admin/configset/index/group/upload.html to gain server control by composing a request for a .txt upload and then changing it to a .php upload. The attacker must have admin access to change the upload_file_ext (aka “Allow upload file suffix”) setting, and must use “php,php” in this setting to bypass the “php” restriction.