intro.html definition, relationships, removal:

This is a part of a malicious parasite that violates user privacy and damages the compromised system. The intro.html file can be used for different purposes depending on the related parasite's type, functionality and carried payload. Although intro.html may not take any malicious actions by itself, it ensures that a parasite is working properly and therefore needs to be removed. DO NOT open, execute or edit intro.html!
The intro.html file is installed and used by D.I.R.T..
Sometimes a presence of intro.html does not indicate that your computer is infected. It can be an essential system file or a file installed by harmless legitimate software and therefore may not pose any threat to your privacy and the system. Although such cases are quite rare, you should thoroughly examine intro.html before completely deleting or leaving it in the system.