See INSTALL for Posix installation information, or for installation
in the Windows operating environment.

What is hexena?

Since you asked, hexena is a contrived acronym for "Haskell EXEcutable aNAlyser."  
The other reference is best left as an exercise to the reader.

Hexena is an implementation of [Encoded Executable File Detection Technique via Executable File Header Analysis][1] which works on the presumption that we are
trying to find other ways to scan executables for malicious code as we
may be fighting a loosing battle using traditional signature based methods.