The files in this directory are the data files required for smb-psexec.nse. 

The .lua files are configurations. Each of these defines a profile for a 
psexec execution. 

nmap_service.exe is a program that facilitates the operation of smb-psexec.nse. 
It is uploaded to the remote host and runs the programs it's directed to run,
redirecting their output to a file. This file is then downloaded by the 
script and displayed to the user. 

When Nmap released version 5.20, it was discovered that some over-zealous
antivirus software tagged this program as spyware[1]. For that reason, when
stored on the host machine, it is now encoded by xoring every byte of the
file with 0xFF. When uploaded to a target machine, it is decoded in-stream. 
This prevents programs on the host machine from tagging it as malicious, but
does not prevent the target from detecting it (which is arguably a good thing). 

The encoder.c program reads a program from stdin, encodes it by xoring with
0xFF, and writes it to stdout. 

[1] http://seclists.org/nmap-dev/2010/q1/198