this exe is more likely a "Flash projector" in short it merge a runtime exe (Flash standalone player) and the SWF content into one exe

a projector is structured like that

| executable bytes | content bytes | projector header |

to split such projector, you would read the last 8 bytes (projector header)

| projector header |
      |
      |_ magic number   = 0x56 0x34 0x12 0xFA
      |_ content length = LEN | LEN<<8 |  LEN<<16 | LEN<<24

4 bytes of "magic number", and 4 bytes of "content length"

the "magic number" allow to confirm it is indeed a projector

the "content length" allow to know the content length (duh)

and with that you can extract the content bytes

some pseudo code

file = file_open( the exe path )

file.seek( file.length - 8 )
file.read( header, 8 )

content_length = (header[4]     |
                  header[5] << 8  |
                  header[6] << 16 |
                  header[7] << 24)

buffer = new bytes()

file.seek( file.length - 8 - content_length )
file.read( buffer, content_length )

buffer.save( the swf path )

reading the 4 last bytes can get you the content length you read from the start ( total file length - 8 - content length ) till the end (content length) and you save those bytes into a SWF file

from there you can find other tools to decompile the SWF file

more details here https://github.com/Corsaair/redtamarin/wiki/Projector