mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-18 17:36:11 +00:00
150 lines
8.5 KiB
NASM
150 lines
8.5 KiB
NASM
CODE_SEG SEGMENT
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ORG 100H ;ORG 100H for a .com file
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ASSUME CS:CODE_SEG,DS:CODE_SEG
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FIRST: JMP ENTRY ;Skip over data area
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COPYRIGHT DB '(C) S. HOLZNER 1984'
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TARGET_FCB DB 37 DUP(0) ;FCB at 6CH will be written over
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END_FLAG DW 0 ;Flag set after everything read
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FILE_SIZE_LO DW 0 ;Low word of file size, in bytes
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FILE_SIZE_HI DW 0 ;High word of same
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FILE_SIZE_K DW 0 ;Number of Clusters to write
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DTA_OFFSET DW 0 ;Used for 1K increments into DTA
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COPY_MSG_1 DB 13,10,'Copy $' ;Part 1 of the copy prompt
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COPY_MSG_2 DB ' (Y/N)?$' ;And part 2
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FULL_MSG DB 13,10,'Disk Full$' ;Trouble message
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MOVE PROC NEAR ;The main (and only) procedure
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ENTRY: MOV CX,32 ;Copy over 1st 32 bytes of default DTA
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MOV SI,6CH ; from 6CH into Target_FCB area for
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LEA DI,TARGET_FCB ; later use as new file name
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REP MOVSB
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MOV DX,5CH ;The source FCB
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MOV AH,11H ;Check if there is match to source file
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INT 21H
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CMP AL,0FFH ;0FFH -> No match
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JNE QUERY ;Match
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JMP OUT ;No Match
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QUERY: MOV AH,9H ;Print out prompt message
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LEA DX,COPY_MSG_1
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INT 21H
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MOV CX,11 ;Print out 11 letters of found file name
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MOV BX,81H ;Point to match in default DTA
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MOV AH,2
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QLOOP: MOV DL,[BX] ;Get letter of found file's name
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INC BX ;Point to next letter
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INT 21H
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LOOP QLOOP ;Keep going until all 11 printed
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MOV AH,9H ;Print out 2nd half of prompt message
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LEA DX,COPY_MSG_2
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INT 21H
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MOV AH,1 ;Get a 1 character response
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INT 21H
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CMP AL,'Y' ;Was it a 'Y'?
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JE DO_COPY ;Yes, copy the file
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CMP AL,'y' ;No...perhaps a 'y'?
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JE DO_COPY ;Yes, copy the file
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JMP NEXT ;Get next match (if none, leave)
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DO_COPY:MOV CX,37 ;Using given target file as a template,
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LEA SI,TARGET_FCB ; load its 37 characters into the FCB
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MOV DI,0C0H ; for use as real target FCB, checking
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CMP BYTE PTR [SI+1],' ' ; for wildcards. First, was DRIVE: given
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JNE NLOOP ; as target? No, check wildcards.
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PUSH DI ;Yes, fill Target_FCB with wildcard ?'s
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PUSH CX ; so found filename will be used
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LEA DI,TARGET_FCB
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INC DI
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MOV CX,11 ;Put in 11 ?'s
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MOV AL,'?'
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REP STOSB ;Do the fill
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POP CX ;Restore counter and dest. pointer
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POP DI
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NLOOP: MOV BX,0 ;Move given target name into real used
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CMP BYTE PTR [SI],'?' ; target FCB at 0C0H. If a wildcard is
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JNE CHAR_OK ; found in given filename use corres-
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MOV BX,80H ; ponding character in found filename
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SUB BX,OFFSET TARGET_FCB ;Wildcard found, adjust source (SI) to
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ADD SI,BX ; point to the found filename
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CHAR_OK:MOVS [DI],[SI]
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SUB SI,BX ;Restore SI if necessary
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LOOP NLOOP ;Loop back until for all 11 name char.s
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MOV DX,80H ;Target FCB now at 0C0H, source at 80H
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MOV AH,0FH ;Use DOS service 15 to open source
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INT 21H ;Open source FCB
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MOV DX,0C0H ;Use DOS service 12 to create target
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MOV AH,16H
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INT 21H ;Create target FCB (or if the file
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AND END_FLAG,0 ; already exists, zero it and refill it)
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MOV BX,80H + 14
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MOV WORD PTR [BX],8000H ;Set record size for source (32K)
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MOV BX,80H + 16 ;Get file size from opened source FCB
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MOV AX,[BX]
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MOV FILE_SIZE_LO,AX ;Store low word of size in FILE_SIZE_LO
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ADD BX,2 ;Point to high word
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MOV DX,[BX]
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MOV FILE_SIZE_HI,DX ;Store high word of size in FILE_SIZE_HI
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MOV CX,1024 ;Div DX:AX (High:Low of size) by 1024
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DIV CX
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MOV FILE_SIZE_K,AX ;Get file size in rounded-up K (1024)
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TEST DX,0FFFFH ;Was it an even K file:Mod(size,1024)=0?
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JZ ROUND ;Yes, don't add cluster for file remnant
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INC FILE_SIZE_K ;No, add 1 more cluster for remainder
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ROUND: MOV BX,0C0H + 14
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MOV WORD PTR [BX],400H ;Set record size for target (1K)
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READ: LEA DX,DATA_POINT ;Set up the 32K DTA we'll use
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MOV AH,1AH ; at the end of this program
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INT 21H
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MOV DX,80H ;Point to source FCB to prepare for read
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MOV AH,14H
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INT 21H ;Do the read of 32K bytes
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CMP AL,0 ;AL = 0 if end of file not yet reached
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JLE READ_OK
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OR END_FLAG,1 ;Have read in the whole file, DTA is
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READ_OK:MOV CX,20H ; stuffed with zeroes after end of file
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LEA DX,DATA_POINT ;Reset our offset into 32K DTA to the
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MOV DTA_OFFSET,DX ; start
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WLOOP: MOV DX,0C0H ;Point to target FCB, prepare for write
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MOV AH,15H
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INT 21H ;Do the write 1K at a time
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CMP AL,0 ;Was the write a success?
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JE COPY_OK ;Yes, check if done writing
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LEA DX,FULL_MSG ;No, assume the disk was full and say so
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MOV AH,9H ;Print error string
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INT 21H
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JMP OUT ;Exit
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COPY_OK:DEC FILE_SIZE_K ;Decrement number of clusters to write
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JZ FINISH ;Done?
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ADD DTA_OFFSET,400H ;No, point to next 1K chunk of DTA
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MOV DX,DTA_OFFSET
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MOV AH,1AH ;Set DTA to match
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INT 21H
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LOOP WLOOP ;Repeat until 32K written or end of file
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TEST END_FLAG,1 ;Have we read in the end of file?
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JZ READ ;No, get next 32K block from source
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FINISH: MOV AX,FILE_SIZE_LO ;Now adjust written file's size
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MOV BX,0C0H + 16 ;Point to low word of size
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MOV WORD PTR [BX],AX ;And set it to the correct value
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ADD BX,2 ;Point to high word of size
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MOV AX,FILE_SIZE_HI ;And set it too
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MOV WORD PTR [BX],AX
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MOV AH,10H ;Request DOS service 16, close files
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MOV DX,0C0H ;Point to target file's FCB
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INT 21H ;Close target with correct size
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MOV DX,80H ;Point to source file's FCB
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INT 21H ;Close source
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NEXT: MOV DX,80H ;Start looking for the next match
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MOV AH,1AH ;First, reset DTA to 80H for found file's FCB
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INT 21H
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MOV AH,12H ;Now search for next match-service 18
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MOV DX,5CH ;Use given filename to match to
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INT 21H
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CMP AL,0 ;Match found?
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JNE OUT ;No, exit.
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JMP QUERY ;Yes, ask if it should be copied
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OUT: RET
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MOVE ENDP
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DATA_POINT: ;The 32K DTA starts here
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CODE_SEG ENDS
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END FIRST ;'END FIRST' so entry point set to FIRST
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