"MAD" Virus (5-June-1990)
Entry............... "MAD" Virus
Alias............... -
Strain.............. -
Detected when....... October 1988
         where...... Helmond (Netherlands)
Clssification....... Boot sector virus
Length of virus..... 512 Bytes
------------------------Preconditions----------------------------------
Operating System(s). Atari TOS
Version\Release..... All versions
Computer models..... All Atari ST
-------------------------Attributes------------------------------------
Easy identification. The words : $7FE,$80F,$8100,$400  can be found 
                     on boot sector at Byte $1D6, and in memory
                     at phystop-$300+$1D6.
Type of infection... Any Boot sector that can be written to.
Infection Trigger... Execution of BIOS disk functions.
Media affected...... Floppy disk drive with device 0 (A:) or 1 (B:). 
Interrupts hooked... hdv_rw vector (used by BIOS disk functions).
Damage.............. Only screen damage:
                        -Change screen address
                        -Rotate screen bytes
                        -Invert screen
                        -Split screen into upper and lower half and
                         change them 
                        -Make a sound (beep)
Damage trigger...... Copy counter = 6 (6 bootsectors infected).
Particularities..... ---
Similarities........ "Anti-2" Virus
-----------------------------------------------------------------------
Countermeasures..... Make sure that the virus is not in memory.
                     Modify the last byte in boot sector to other value.
Standard means...... Clear all bytes in boot sector beginning at
                     offset 30 decimal.
-----------------------Acknowledgements--------------------------------
Location............ Virus Test Center, University of Hamburg, FRG
Classification by... Andre' Schaper
Documentation by.... Andre' Schaper
Information Source.. George R. Woodside
Date................ 5-June-1990

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