CHALLENGE.EXE (MD5: BF5EFF788E98056A3ED299CA836A3721) is a test file made
by F-Secure Viruslab staff.

This file is not malicious. It's part of a competition held by the T2 Data 
Security Conference in Finland. If you find the secret message and a secret 
email address from the binary you can win a free ticket to the conference.

For more info, see http://www.t2.fi/