[Summary] The Pronestor service "PNHM" (aka Health Monitoring or HealthMonitor) before 220.127.116.11 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 18.104.22.168 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 22.214.171.124 and older Also tested on version 126.96.36.199 with same result. Discovered: 06-nov-2018 Reported: 07-nov-2018 Vendor: https://www.pronestor.com/ Vendor confirmed: True Fixed: Version 188.8.131.52 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.