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Directory Traversal in DevExpress ASP.NET File Manager

During a penetration test RedTeam Pentesting discovered a directory
traversal vulnerability in DevExpress' ASP.NET File Manager and File
Upload. Attackers are able to read arbitrary files by specifying a
relative path.

Details
=======

Product: DevExpress ASPxFileManager Control for WebForms and MVC
Affected Versions: DevExpress ASPxFileManager v10.2 to v13.2.8
Fixed Versions: DevExpress ASPxFileManager v13.2.9
Vulnerability Type: Directory Traversal
Security Risk: high
Vendor URL:
    https://www.devexpress.com/Products/NET/Controls/ASP/File-Upload-Explorer/
Vendor Status: fixed version released
Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2014-006
Advisory Status: published
CVE: CVE-2014-2575
CVE URL: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-2575


Introduction
============

"The DevExpress ASP.NET Subscription includes a standalone Multi-File
Upload Manager for WebForms and MVC and a pre-built File Manager for
WebForms; built so you can instantly introduce file management
capabilities in your next web application."

(from DevExpress' Homepage)


More Details
============

The ASPX File Manager component is prone to a directory traversal
vulnerability. Attackers with access to the File Manager component can
read arbitrary files on the same partition as the shared directory.

A common request to download a file via the File Manager component
requires multiple HTTP-Post parameters:

__EVENTTARGET=ctl00%24ContentPlaceHolder1%24ASPxFileManager1
__EVENTARGUMENT=13%7C<file.ext>
__EVENTVALID=

The parameter __EVENTARGUMENT=13|<file.ext> specifies a file download
and the file which is to be downloaded. Attackers may also request files
outside of the shared directory by prepending a relative path to a
parent directory.


Proof of Concept
================

By requesting files with a relative path, files otherwise not available
will be accessible through the File Manager component.  Depending on the
shared directory and the webserver configuration, the webserver
configuration file might for example be accessible through the File
Manager component:

__EVENTARGUMENT=13|../../web.config

Other sensitive operating system files could be affected, too.

Example exploit:
------------------------------------------------------------------------
curl --data __EVENTTARGET=ctl00%24ContentPlaceHolder1%24ASPxFileManager1\
"&__EVENTARGUMENT=13%7C../../web.config&=&__EVENTVALID" \
http://example.com/FileManagerComponent.aspx
------------------------------------------------------------------------

The request above will download the specified file.


Workaround
==========

Instead of a physical file system provider, a database file system
provider with limited access permissions could be used.


Fix
===

Update ASPxFileManager control to DevExpress libraries version v13.2.9.


Security Risk
=============

The risk is estimated to be high. This vulnerability allows attackers to
access arbitrary files on the same partition as the File Manager's root
directory. This may allow attackers to read sensitive information like
the webserver configuration.


Timeline
========

2014-03-10 Vulnerability identified
2014-03-21 Customer approved disclosure to vendor
2014-03-21 CVE number requested and assigned
2014-03-25 Vendor notified
2014-04-11 Customer opened support ticket with vendor
2014-04-17 Vendor released fixed version
2014-04-17 Vendor released security advisory to customers
2014-06-05 Advisory released


References
==========

Vendor Security Advisory:
http://security.devexpress.com/de7c4756/?id=ff8c1703126f4717993ac3608a65a2e2


RedTeam Pentesting GmbH
=======================

RedTeam Pentesting offers individual penetration tests, short pentests,
performed by a team of specialised IT-security experts. Hereby, security
weaknesses in company networks or products are uncovered and can be
fixed immediately.

As there are only few experts in this field, RedTeam Pentesting wants to
share its knowledge and enhance the public knowledge with research in
security-related areas. The results are made available as public
security advisories.

More information about RedTeam Pentesting can be found at
https://www.redteam-pentesting.de.