Introduction
SCA is a computer virus written for the Commodore Amiga. The virus is the first know virus every created on the Amiga therefore it is well know within the Amiga community. Due the fact that it is a simple, not encrypted bootvirus many clones of the virus exist. Because of this fact I will not spend an entire wiki-page for each clone but list the clones only here on this site / redirect to this SCA page directly.
Summary
- Overwrites the original bootblock of any unprotected disk inserted in the floppy drive of an Amiga computer
- Stays resident in memory by using CoolCapture
- Uses the operating system call DoIO() for infection
Details
After booting with an infected disk the virus copies itself to RAM (ChipMem) adress $7EC00 without explicit allocation of that RAM-area. This isn't good and causes the Amiga to crash if a program overwrites this location lateron. After that the virus occupies the DoIO()-Vector of the exec.library for infection and makes itself resident by using the CoolCapture.
Every 15th infection the virus starts a graphical routine which displays following message:
If you boot the Amiga with an infected disk while pressing the left mouse-button the virus will deinstall itself from memory. As an indicator the screen will turn green:
checkmouse:
btst #6,$BFE001 ; Left mouse-button pressed?
bne.s not_pressed
clr.l $2E(a6) ; Removes virus from CoolCapture
bsr.w calc_chksum ; -"- -"-
lea $DFF000,a5
move.w #$60,$180(a5) ;Set screencolor to green
not_pressed:
(...) ; Installs virus in memory
Clones and variants
- SCA-666
- SCA-2001
- SCA-AIDS
- SCA-Anti Kanacken
- SCA-Assassin
- SCA-Asylant
- SCA-Baltasar
- SCA-Bad Bytes 4
- SCA-Big Boss
- SCA-Blade Runners
- SCA-BS1
- SCA-D&A
- SCA-DAG
- SCA-Deniz
- SCA-Disk Terminator
- SCA-ICE
- SCA Karl Marx
- SCA-Kefrens
- SCA-MAX
- SCA-NASA
- SCA-PAL
- SCA-PDS
- SCA-PKK
- SCA-Sphinx
- SCA-TAI
- SCA-TNK
