OpenVPN Private Tunnel Core Service Unquoted Service Path Elevation Of Privilege


Vendor: OpenVPN Technologies, Inc
Product web page: http://www.openvpn.net
Affected version: 2.1.28.0 (PrivateTunnel 2.3.8)

Summary: Private Tunnel is a new approach to true Internet security creating
a Virtual Private Tunnel (VPT) or Virtual Private Network (VPN) that encrypts,
privatizes, and protects your Internet traffic.

Desc: Private Tunnel application suffers from an unquoted search path issue
impacting the Core Service 'ptservice' service for Windows deployed as part
of PrivateTunnel bundle. 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.

Tested on: Microsoft Windows 7 Professional SP1 (EN)
           Microsoft Windows XP Professional SP3 (EN)


Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
                            @zeroscience


Advisory ID: ZSL-2014-5192
Advisory URL: http://www.zeroscience.mk/en/vulnerabilities/ZSL-2014-5192.php


07.07.2014

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

SERVICE_NAME: ptservice
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : C:\Program Files (x86)\OpenVPN Technologies\PrivateTunnel\ptservice.exe
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : Private Tunnel Core Service
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem

C:\Users\user>icacls "C:\Program Files (x86)\OpenVPN Technologies\PrivateTunnel\ptservice.exe"
C:\Program Files (x86)\OpenVPN Technologies\PrivateTunnel\ptservice.exe NT AUTHORITY\SYSTEM:(I)(F)
                                                                        BUILTIN\Administrators:(I)(F)
                                                                        BUILTIN\Users:(I)(RX)

Successfully processed 1 files; Failed processing 0 files

C:\Users\user>