Blenders scripting language - Python - is available in the 3D Plug-in, stand-alone player and run-times as well. Since Python is an extremely powerful language, we had to make sure that Blender 3D plug-in content using Python cannot be used to perform any actions that can cause loss of files or other harm to your system.
This could be:
Trojan Horses: a program which sets up a network connection in the background, allowing access to the clients machine or sending back relevant data to the hacker.
Viruses: programs that may alter system configuration files or executables and reproduce themselves that way
The Python implementation in the Blender 3D plug-in prevents the above by:
Disabling file open functionality, meaning, no writing or reading of files is possible
Disabling access to external modules, e.g. prohibiting network access, manipulation of the file system, memory, or any other functionality that is not related to the played back content.
Full Python functionality is available in the stand-alone player.