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[Summary]
The Pronestor service "PNHM" (aka Health Monitoring or HealthMonitor) 
before 8.1.12.0 has "BUILTIN\Users:(I)(F)" permissions for 
the "%PROGRAMFILES(X86)%\proNestor\Outlook add-in for Pronestor\PronestorHealthMonitor.exe" file, 
which allows local users to gain privileges via a Trojan horse PronestorHealthMonitor.exe file.

During the installation of Pronestors Outlook-Add-In (version 8.1.11.0 
and older) the installer creates a service named PNHM (Pronester 
Health Monitoring) with weak file permission running as SYSTEM.
The vulnerability allows all "Authenticated Users" to potentially 
execute arbitrary code as SYSTEM on the local system.

[Additional Information]
Tested on Windows 7.
Version: Outlook Add-In 8.1.11.0 and older
Also tested on version 5.1.6.0 with same result.
Discovered: 06-nov-2018
Reported: 07-nov-2018

Vendor: https://www.pronestor.com/
Vendor confirmed: True
Fixed: Version 8.1.12.0
Attack Type: Local Privilege Escalation
Vulnerability due to: Insecure Permissions
Discoverer: PovlTekstTV
CVE: 2018-19113
Original link: https://gist.github.com/povlteksttv/8f990e11576e1e90e8fb61acf8646d28

[Proof]
C:\Users\povltekst>sc qc PNHM

SERVICE_NAME: PNHM
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : "C:\Program Files (x86)\proNestor\Outlook add-in for Pronestor\PronestorHealthMonitor.exe"
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : Pronestor HealthMonitor
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem

C:\Users\povltekst>icacls 'C:\Program Files (x86)\proNestor\Outlook add-in for Pronestor\PronestorHealthMonitor.exe'
C:\Program Files (x86)\proNestor\Outlook add-in for Pronestor\PronestorHealthMonitor.exe
         BUILTIN\Users:(I)(F)
         NT AUTHORITY\SYSTEM:(I)(F)
         BUILTIN\Administrators:(I)(F)

Notice: "BUILIN\Users:(I)(F)". (F) = Full access!
This means that an authenticated user can change the file

[Attack Vectors]
Replace the file "PronestorHealthMonitor.exe" with a malicious file 
also called "PronesterHealthMonitor.exe". Next time the service (PNHM) 
starts, the malicious file will get executed as SYSTEM. The service 
starts on every reboot.

[Affected Component]
PronestorHealthMonitor.exe
This exe will be executed on every reboot by a service named PNHM running as SYSTEM.