.EXE1 File Extension
What is an EXE1 file?
Windows executable (.EXE) file renamed so that it cannot be run natively in Windows by double-clicking the file; can be used by software installers when the developer doesn't want users to be able to run the executable.
An example of the EXE1 extension is Steam's installer, which uses the filename steam.exe1. This installer is included on some Steam game discs.
NOTE: If you want to run an EXE1 file, you can rename ".exe1" to ".exe" and open it.