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[Full-disclosure] Barracuda Appliances - Validation Filter Bypass Vulnerability
- To: full-disclosure@xxxxxxxxxxxxxxxxx
- Subject: [Full-disclosure] Barracuda Appliances - Validation Filter Bypass Vulnerability
- From: Vulnerability Lab <research@xxxxxxxxxxxxxxxxxxxxx>
- Date: Wed, 01 Aug 2012 05:30:21 +0200
Title:
======
Barracuda Appliances - Validation Filter Bypass Vulnerability
Date:
=====
2012-07-16
References:
===========
http://www.vulnerability-lab.com/get_content.php?id=661
VL-ID:
=====
661
Common Vulnerability Scoring System:
====================================
5.5
Abstract:
=========
The Vulnerability Laboratory Research Team discovered a input validation filter
bypass vulnerability in Barracudas Network appliance products.
Report-Timeline:
================
2012-06-09: Researcher Notification & Coordination
2012-06-10: Vendor Notification
2012-07-12: Vendor Response/Feedback
2012-07-14: Vendor Fix/Patch
2012-07-16: Public Disclosure
Status:
========
Published
Exploitation-Technique:
=======================
Remote
Severity:
=========
High
Details:
========
A filter bypass vulnerability is detected in the Barracuda Networks Appliances
Applications. Remote attackers
with privileged user accounts bypass the application internal filter &
exception-handling. Successful exploitation
of the vulnerability result in dbms (Server) or application (Web) compromise.
Exploitation requires low or medium
user inter action & with privileged user account.
The input filter blocks persistent input attacks with a restriction/filter
exception for double quotes, <>,frames,
scripts & statements. The vulnerability allows to bypass the existing input
validation filter & exception handling.
The bug is located when processing to save the url path name (db stored) with
attached file. The vulnerability
allows to bypass the path url name parse restriction which leads to the
execution on a secound vulnerable bound
module which displays the input as output listing. The Account MyResource
Display (example listing + input) & Upload
File modules are executing the earlier saved `save` path of url-path/folder
which leads to the bypass of the input
validation filter & exception-handling. The result is the persistent execution
of malicious script codes out of the
security appliance application context.
The vulnerability allows to bypass this method with this tricky way ...
The url path function save the context of the input path name(parsed) as client
side request (GET) via URL. If the
request is getting bound with the file (POST), which is getting stored
(persistent) displayed later on the overview
listings, the code will be unauthorized executed out of the security
application context(persistent|server-side).
Vulnerable Module(s):
[+] MyResource, File System & File Upload Output/Input
- Input Validation Filter Restriction & Listing
NOTE: The vulnerability is also located on different other security appliances
on all resource listings or file uploads with url path save.
Proof of Concept:
=================
The vulnerability can be exploited by local low privileged user accounts & with
medium or high required user inter action.
For demonstration or reproduce ...
Manually ...
1. Login into for example the SSL VPN appliance
2. Switch over to the MyResources File System
3. Open via Tamper the following url ...
fileSystem.do?ActionTarget=list&path=smb/random folder/
4. Now save the path and switch to new folder
5. The setting of the path has been implemented automatic. Change the Path to
your scriptcode after it has been parsed.
6. Now switch after the save to the uplaod files function. Upload any random
file which is bound to the malicious title.
7. Save the file and the code is getting executed in the main index of the
preview in myresources.
<a href="?launchId=l7e68d5&startRow=0&
path=smb%2F%22%3E%3C[PERSISTENT SCRIPT CODE
EXECUTION!]+%3C&pageSize=25&sortReverse=
false&sortName=fileSystem.size&
amp;amp;actionTarget=list" class="columnHeader">Size</a>
</td>
... or
<span><a
href="fileSystem.do?actionTarget=list&launchId=l7e68d5&path=smb/Sales%20Folder">Sales
Folder
</a> / <a
href="fileSystem.do?actionTarget=list&launchId=l7e68d5&path=smb/Sales%20Folder/Testing%20from%20Tri%20Opt">
Testing from Tri Opt</a> /​​​​​ <a
href="fileSystem.do?actionTarget=list&
launchId=l7e68d5&path=smb/Sales%20Folder/
Testing%20from%20Tri%20Opt/%22%3E%3C[PERSISTENT SCRIPT CODE INJECT VIA
PATH%22%29%20%3C">
"​​​​​><[PERSISTENT SCRIPT CODE EXECUTION!]'
<<="" a=""> / </span></div>
Reference(s):
../video-poc.wmv
Solution:
=========
The vulnerability can be fixed by parsing the secound input request of the file
upload function next to the display of the myresource listing.
To fix the issue completly it is also required to parse the path url request
which allows to include but not execute the context.
2012-07-14: Vendor Fix/Patch by Barracuda Networks
Risk:
=====
The security risk of the input validation filter bypass vulnerability is
estimated as high(-).
Credits:
========
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri
(bkm@xxxxxxxxxxxxxxxxxxxxx)
Disclaimer:
===========
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