This should help: (You must be running security that has changed the name)
Compressed .ZIP or executable .EXE file renamed by CA Security Centre to have a ".efw" extension; typically applies to e-mail attachments scanned by Computer Associates (CA) antivirus software.
EFW zipped files
may be opened by changing the file extension to ".zip" and opening the file with a decompression utility, such as WinZip or Stuffit Expander; executable files may be run directly by changing the file extension to ".exe" and opening the file.
PW
