%%File: VIRS0431.TXT
%%Name/Aliases: Happy Days Trojan, HD Trojan
%%Platform: PC/MS-DOS
%%Type: Trojan., 
%%Disk Location: happyday.zip
%%Features: 
%%Damage: Deletes or moves files.
%%Size: 
%%See Also: 
%%Notes: The Happy Days trojan is being distributed via e-mail on 
America Online in the file happyday.zip around 2/1/96. It is supposed to 
improve the performance of a system.
The distribution contains 4 files:

   INSTALL.EXE	
  NECUSER3.TYE	
  README.TXT
  RUNMENOW.COM

The Readme file contains the following text:

Hello, you are running Happy Days (R).
 version 2.0
This program is a miracle b/c of its 
size and its effectiveness. Run any
day, any time, and it increases your
productivity on the computer. Now we
all know how unproductive our sessions
at the computer can be, and this nifty
program will cure them all. Have a
Happy Day! with Happy Days (R) v2.0.

RUN the file RUNMENOW.COM in DOS only!!

If you run the runmenow.com file it displays the following text:

This program is this ultimate in home entertainment.
The magic of it is that it takes up minimal room on your harddrive, 
  and it doesn't use any precious RAM.
This file, RUNMENOW.COM, and its corresponding file INSTALL.EXE
  work together. Remember, this file is universal and is great to use.
See README.TXT for documentation.
MAKE SURE YOU ARE IN DOS BEFORE RUNNING!!
Strike any key when ready...
Running Happy Day (R) v2.0...

The runmenow.com file runs install.exe which copies itself to the root 
directory of your C: drive and deletes files in the \dos, \windows and 
\windows\system directories. The Trojan tries to execute some other DOS 
commands, but they fail because it has already deleted the contents of 
the \dos directory.