Google is your friend, you could have found that yourself if I could.
Quote:
.EFW File Extension
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.
|
Source:
http://www.fileinfo.net/extension/efw