This is a fast infector, which infects COM files when they are executed or accessed. Blue_Nine is a stealth virus, making the size of the infected files seem to be the original. Blue_Nine has lots of antiheuristics features, but it also contains several bugs.
Disinfection & Removal
There are several variants of Blue_Nine. The original variant (Blue_Nine.925.A) contains this text:
Blue Nine Virus by Conzouler 1994
This variant contains this text:
It's only a lil lightfearing creature
This variant does nothing but spreads.
Technical Details: Peter Szor, F-Secure, 1996