Disable OS/2 and POSIX subsystem
- Start the registry editor and remove the following entries:
- [HKEY_LOCAL_MACHINE \SOFTWARE \Microsoft \OS/2 Subsystem for NT]
- [HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Control \Session Manager \Environment]
Os2LibPath= - [HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Control \Session Manager \SubSystems]
Optional=
OS2=
Posix=
- Enter the %Windir%\System32\Dllcache directory and remove these files (Because of Windows File Protection)
- os2.exe
- os2ss.exe
- os2srv.exe
- Enter the %Windir%\System32 directory and rename/remove these files:
- os2.exe
- os2ss.exe
- os2srv.exe
- psxss.exe
- posix.exe
- psxdll.dll
- Enter the %Windir%\System32\OS2 directory and rename/remove these files:
- All files except the DLL folder and its contents
Note that with Windows XP the OS2 and POSIX subsystem is not installed, though the registry entries are still created. More Info MS KB308259
Credits NSA Win2k Security Guide
Credits NSA WinXP Security Guide
Is it possible to add back OS/2 support to XP (maybe copying the appropriate system files from an NT or 2000 system & updating the registry)?
If you use HIEW6.11 as your favorite hex editor, you should never do the suggested things. HIEW won't start anymore since it has both DOS and OS/2 modules in one EXE...
It of course can be fixed (change NE signature to something else) but is quite annoying at the beginning :(
Have updated the tip about making sure that one is not using cross platform executables that are dependent of the OS/2 subsystem (Though have a feeling that most will first discover, that they are using such applications, when they have actually disabled os/2 subsystem like you did)