FAUST iServer 9.0.018.018.4 Local File Inclusion

`SEC Consult Vulnerability Lab Security Advisory < 20220120-0 >  
=======================================================================  
title: Local file inclusion vulnerability  
product: Land Software - FAUST iServer  
vulnerable version: 9.0.017.017.1-3 - 9.0.018.018.4  
fixed version: 9.0.019.019.7, Version 10  
CVE number: CVE-2021-34805  
impact: high  
homepage: https://www.land-software.de  
found: 2021-05-25  
by: Mario Keck (Atos Germany)  
SEC Consult Vulnerability Lab  
  
An integrated part of SEC Consult, an Atos company  
Europe | Asia | North America  
  
https://www.sec-consult.com  
  
=======================================================================  
  
Vendor description:  
-------------------  
(German) "Der FAUST iServer bringt Ihre FAUST- , FAUST Entry- und LIDOS-Datenbanken  
ins Intranet und Internet. Er bietet hohe Sicherheit und eine einfache  
Installation."  
  
Source: http://www.land-software.de/lfs.fau?prj=iweb&dn=faust+iserver  
  
  
Business recommendation:  
------------------------  
The vendor provides a hotfix for the identified vulnerable versions. As the  
most actual version v10 of FAUST iServer is not vulnerable, no immediate action in  
the form of a patch is required. The webroot of the server should not be on the  
same partition as the operating system's root partition.  
  
  
Vulnerability overview/description:  
-----------------------------------  
1) Local File Inclusion (CVE-2021-34805)  
When a URL is requested, the FAUST iServer checks for the corresponding ".fau"  
file on the operating system. ".fau" files can be compared with compiled  
webserver pages for displaying the content of the webpage. The identified  
vulnerable versions of FAUST iServer do not properly protect against a request  
aiming to read local files of the operating system.  
  
FAUST iServer is designed to work on Windows operating systems only.  
Therefore, by simply URL-encoding a path like  
..\..\..\windows\win.ini into %2e%2e%5c%2e%2e%5c%2e%2e%5cwindows%5cwin.ini  
the FAUST iServer returns the contents of win.ini  
  
  
Proof of concept:  
-----------------  
1) Local File Inclusion (CVE-2021-34805)  
The following proof of concept shows the HTTP request that was used to read  
local files of the server's operating system.  
The vulnerability, as shown in the proof of concept request below, can be  
triggered as soon as a vulnerable version of FAUST iServer is in use. To read  
operating system specific files, the webroot of FAUST iServer has to be located  
on the same partition as the operating system root.  
Authorization is not needed.  
  
-------------------------------------------------------------------------------  
HTTP Request:  
GET /%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5c%2e%2e%5cwindows%5cwin.ini HTTP/1.1  
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko  
Connection: keep-alive  
Host: <IP>  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8  
Accept-Language: en-US,en;q=0.9  
-------------------------------------------------------------------------------  
  
Vulnerable / tested versions:  
-----------------------------  
The following versions have been tested and found to be vulnerable:  
* 9.0.017.017.1-3  
* 9.0.018.018.4  
  
  
Vendor contact timeline:  
------------------------  
2021-06-10: Contacting vendor via email.  
2021-06-14: Vendor requested more information about the vulnerability, which  
was provided on the same day.  
2021-06-15: Requested information from vendor to check which versions are  
vulnerable.  
2021-06-17: Vendor informed researcher about upcoming update and promised to  
inform all customers about the critical security fix in it.  
2021-08-09: Confirmed the security fix in FAUST iServer 9.0.019.019.7.  
2021-08-16: Researcher received a notification mail from the vendor's  
newsletter announcing the official release of the fixed version.  
2022-01-12: Version 10 was officially released and is available for all  
customers for upgrade.  
2022-01-20: Release of security advisory  
  
  
Solution:  
---------  
The vulnerability is fixed in the following version:  
* 9.0.019.019.7  
  
This patch should be immediately installed.  
  
Version 10 is not affected by this vulnerability, if possible it is recommended  
to upgrade to this version.  
  
  
Workaround:  
-----------  
None  
  
  
Advisory URL:  
-------------  
https://sec-consult.com/vulnerability-lab/  
  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
SEC Consult Vulnerability Lab  
  
SEC Consult, an Atos company  
Europe | Asia | North America  
  
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the evaluation of new offensive and defensive technologies for our customers.  
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EOF Mario Keck / @2022  
  
  
`