Email-Worm.Win32.Pikachu or Pikachu is a worm on Microsoft Windows that spreads through email, and was believed to be the first worm that was aimed at children and teenage users, as it was named after the character in the Pokémon franchise. It is written in Visual Basic 6.0.
The website featured just redirects to Pikachu's entry on the Pokémon Pokédex site. During the time the worm was active, there was a pikachu-related gaming website that was completely unaffiliated with the worm.
This worm spreads via email using Microsoft Outlook and spreads in E-Mail letters with the attached file "PikachuPokemon.exe". The icon is a crudely drawn Pikachu. The worm itself is a Win32 PE executable file, and the file size is about 32 KB.
When the worm runs, first of all it overwrites the original C:\AUTOEXEC.BAT file with instructions that will delete all files in the Windows and Windows system directory. It displays a picture of Pikachu and some text:
Between millions of people around the world I found you. Don't forget to remember this day every time MY FRIEND! Visit us at http://www.pikachu.com
It searches the address book of Microsoft Outlook and creates letters for e-mail addresses in the Outbox folder.
Subject: Pikachu Pokemon. Text: Great Friend! Pikachu from Pokemon Theme have some friendly words to say. Visit Pikachu at http://www.pikachu.com See you.
And to each letter, the worm attaches itself as the file PikachuPokemon.exe.
The worm was sent to everyone in that person's address book and it would add the following lines to AUTOEXEC.BAT, which is located in the root directory of the drive Windows 95/98/ME was installed on. (i.e. C:\autoexec.bat). These lines were as follows:
@echo off del C:\WINDOWS\*.* del C:\WINDOWS\SYSTEM\*.*
After this, if the user resets their computer, according to the batch file overwritten by the worm, it attempts to delete all the files in C:\WINDOWS and also its subdirectory SYSTEM, however the system will prompt for this action, making the user to notice that some files have been modified maliciously. This also fails if the Windows directory is not in C:\WINDOWS.
File deletion command is always prompted on issuing in Windows GUI, but not in command line, however the system will prompt when the user attempts to delete all files in any type in a certain directory, this is a security measure. Here are some examples of file deletion in command line mode.
Execute without prompt:
Prompt before execution:
However in the DOS version of command line, including Windows 9x systems, there is no method to bypass this.