Home » Archimedes archive » Micro User » MU 1992-02.adf » !VKiller/Docs/ThanDoc

!VKiller/Docs/ThanDoc

This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.

Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.

Tape/disk: Home » Archimedes archive » Micro User » MU 1992-02.adf
Filename: !VKiller/Docs/ThanDoc
Read OK: ✔
File size: 0E92 bytes
Load address: FFFFFF43
Exec address: 2B52858F
Duplicates

There are 7 duplicate copies of this file in the archive:

File contents
This is very detailed (although stopping short of a disassembly of course)
description of the Thanatos Virus. It is strongly recommended reading, if only
to give you a better understanding of how the virus operates.

Thanatos Virus technical information
------------------------------------

This is an encrypted (simple EOR with &7A, lower-case "z") BASIC program
(crypted = 11756 (&2DEC) bytes long, TOP-PAGE of BASIC program = 7660 (&1DEC)
bytes) called "RISCOSext" with a filetype of Absolute (yes, a very poor piece
of ARM code decrypts and runs it and wastes nearly 4K of space between &8100
and &9000 !). Associated with it is a Sprite file (actually of filetype Module)
called "TaskAlloc", which is 344 bytes long containing a rude sprite to replace
the mouse pointer..

When run, it installs itself as a Wimp task named "Thanatos" and then looks
for double-clicks to infect application directories (copies the RISCOSext
and TaskAlloc files into there and then appends the 'usual' string to the !Boot
file (to run RISCOSext).

The nasty section of the Thanatos Virus REALLY IS nasty, so I urge you to
study this carefully. Here's a list of things that can happen:

Rough once every 100000 times around the Wimp_Poll loop, Thanatos can:

* 2 out of 13 chances: Shut down icon bar application at random (whilst
  displaying its own icon bar icon during the shutdown).

* 1 out of 13 chances: Cause a Desktop Quit.

* 3 out of 13 chances: Reverse the mouse pointer step (sets it -2).

* 1 out of 13 chances: Crash the machine by poking a duff instr at the start
  of memory.

* 1 out of 13 chances: Randomise the 240 bytes of CMOS.

* 4 out of 13 chances: Randomly display one of 8 very rude messages - one of
  which also changes the mouse pointer shape to a rude graphic and another
  will also shutdown an icon bar application (the same routine as above).

* 1 out of 13 chances: Wipe the contents of <Obey$Dir>.

It also has a "special date" section as follows:

Any Friday 13th: Advertises its own "virus killer" (from Armen Software).

April 1st: 10 Address exception errors, followed by coloured rectangles and
a 'stuck' mouse pointer for 10 seconds. An "April Fool" message is then
displayed.

December 25th: Destroys the disk map of ADFS drives 0, 4 and 5 followed by
a "Merry Chrimble" message.

October 31st: Formats the floppy in drive 0, followed by a "Spooky" message.

January 1st: As December 25th, but followed by a New Year's Resolution
message (to keep your disks write-protected :-( ).

Killing the Thanatos Virus (which one ??)
--------------------------

There appears to be *TWO* versions of the Thanatos Virus - one with debugging
REM statements (usually with the string "*dbg*" in them) and one without.
However, both appear to be identical in function, so I've treated them both
as the same virus. To kill them, simply sending a Message_Quit to the Wimp Task
isn't good enough (comes back with a rude message if you do). VKiller modifies
the BASIC program ("in situ") to quit properly - after checking whether it is
the 'debug' version or not.

My copy of the Thanatos virus has a major fault - it uses the END=<expression>
syntax to adjust BASIC's memory usage, but gives too low a value - hence it
never runs properly (immediately crashes with "No room for this DIM" error).
For purposes of testing, I boosted the END value (on the assumption that the
virus author would eventually fix this mistake).

Thanatos Virus Innoculation
---------------------------

Temporary innoculation can be achieved by setting Sys$Path to any value
(VKiller's !Boot now does this), because this is checked by the Thanatos
Virus to see if it is already present in the system. Permanent innoculation
is not possible.

00000000  54 68 69 73 20 69 73 20  76 65 72 79 20 64 65 74  |This is very det|
00000010  61 69 6c 65 64 20 28 61  6c 74 68 6f 75 67 68 20  |ailed (although |
00000020  73 74 6f 70 70 69 6e 67  20 73 68 6f 72 74 20 6f  |stopping short o|
00000030  66 20 61 20 64 69 73 61  73 73 65 6d 62 6c 79 20  |f a disassembly |
00000040  6f 66 20 63 6f 75 72 73  65 29 0a 64 65 73 63 72  |of course).descr|
00000050  69 70 74 69 6f 6e 20 6f  66 20 74 68 65 20 54 68  |iption of the Th|
00000060  61 6e 61 74 6f 73 20 56  69 72 75 73 2e 20 49 74  |anatos Virus. It|
00000070  20 69 73 20 73 74 72 6f  6e 67 6c 79 20 72 65 63  | is strongly rec|
00000080  6f 6d 6d 65 6e 64 65 64  20 72 65 61 64 69 6e 67  |ommended reading|
00000090  2c 20 69 66 20 6f 6e 6c  79 0a 74 6f 20 67 69 76  |, if only.to giv|
000000a0  65 20 79 6f 75 20 61 20  62 65 74 74 65 72 20 75  |e you a better u|
000000b0  6e 64 65 72 73 74 61 6e  64 69 6e 67 20 6f 66 20  |nderstanding of |
000000c0  68 6f 77 20 74 68 65 20  76 69 72 75 73 20 6f 70  |how the virus op|
000000d0  65 72 61 74 65 73 2e 0a  0a 54 68 61 6e 61 74 6f  |erates...Thanato|
000000e0  73 20 56 69 72 75 73 20  74 65 63 68 6e 69 63 61  |s Virus technica|
000000f0  6c 20 69 6e 66 6f 72 6d  61 74 69 6f 6e 0a 2d 2d  |l information.--|
00000100  2d 2d 2d 2d 2d 2d 2d 2d  2d 2d 2d 2d 2d 2d 2d 2d  |----------------|
*
00000120  2d 2d 0a 0a 54 68 69 73  20 69 73 20 61 6e 20 65  |--..This is an e|
00000130  6e 63 72 79 70 74 65 64  20 28 73 69 6d 70 6c 65  |ncrypted (simple|
00000140  20 45 4f 52 20 77 69 74  68 20 26 37 41 2c 20 6c  | EOR with &7A, l|
00000150  6f 77 65 72 2d 63 61 73  65 20 22 7a 22 29 20 42  |ower-case "z") B|
00000160  41 53 49 43 20 70 72 6f  67 72 61 6d 0a 28 63 72  |ASIC program.(cr|
00000170  79 70 74 65 64 20 3d 20  31 31 37 35 36 20 28 26  |ypted = 11756 (&|
00000180  32 44 45 43 29 20 62 79  74 65 73 20 6c 6f 6e 67  |2DEC) bytes long|
00000190  2c 20 54 4f 50 2d 50 41  47 45 20 6f 66 20 42 41  |, TOP-PAGE of BA|
000001a0  53 49 43 20 70 72 6f 67  72 61 6d 20 3d 20 37 36  |SIC program = 76|
000001b0  36 30 20 28 26 31 44 45  43 29 0a 62 79 74 65 73  |60 (&1DEC).bytes|
000001c0  29 20 63 61 6c 6c 65 64  20 22 52 49 53 43 4f 53  |) called "RISCOS|
000001d0  65 78 74 22 20 77 69 74  68 20 61 20 66 69 6c 65  |ext" with a file|
000001e0  74 79 70 65 20 6f 66 20  41 62 73 6f 6c 75 74 65  |type of Absolute|
000001f0  20 28 79 65 73 2c 20 61  20 76 65 72 79 20 70 6f  | (yes, a very po|
00000200  6f 72 20 70 69 65 63 65  0a 6f 66 20 41 52 4d 20  |or piece.of ARM |
00000210  63 6f 64 65 20 64 65 63  72 79 70 74 73 20 61 6e  |code decrypts an|
00000220  64 20 72 75 6e 73 20 69  74 20 61 6e 64 20 77 61  |d runs it and wa|
00000230  73 74 65 73 20 6e 65 61  72 6c 79 20 34 4b 20 6f  |stes nearly 4K o|
00000240  66 20 73 70 61 63 65 20  62 65 74 77 65 65 6e 20  |f space between |
00000250  26 38 31 30 30 0a 61 6e  64 20 26 39 30 30 30 20  |&8100.and &9000 |
00000260  21 29 2e 20 41 73 73 6f  63 69 61 74 65 64 20 77  |!). Associated w|
00000270  69 74 68 20 69 74 20 69  73 20 61 20 53 70 72 69  |ith it is a Spri|
00000280  74 65 20 66 69 6c 65 20  28 61 63 74 75 61 6c 6c  |te file (actuall|
00000290  79 20 6f 66 20 66 69 6c  65 74 79 70 65 20 4d 6f  |y of filetype Mo|
000002a0  64 75 6c 65 29 0a 63 61  6c 6c 65 64 20 22 54 61  |dule).called "Ta|
000002b0  73 6b 41 6c 6c 6f 63 22  2c 20 77 68 69 63 68 20  |skAlloc", which |
000002c0  69 73 20 33 34 34 20 62  79 74 65 73 20 6c 6f 6e  |is 344 bytes lon|
000002d0  67 20 63 6f 6e 74 61 69  6e 69 6e 67 20 61 20 72  |g containing a r|
000002e0  75 64 65 20 73 70 72 69  74 65 20 74 6f 20 72 65  |ude sprite to re|
000002f0  70 6c 61 63 65 0a 74 68  65 20 6d 6f 75 73 65 20  |place.the mouse |
00000300  70 6f 69 6e 74 65 72 2e  2e 0a 0a 57 68 65 6e 20  |pointer....When |
00000310  72 75 6e 2c 20 69 74 20  69 6e 73 74 61 6c 6c 73  |run, it installs|
00000320  20 69 74 73 65 6c 66 20  61 73 20 61 20 57 69 6d  | itself as a Wim|
00000330  70 20 74 61 73 6b 20 6e  61 6d 65 64 20 22 54 68  |p task named "Th|
00000340  61 6e 61 74 6f 73 22 20  61 6e 64 20 74 68 65 6e  |anatos" and then|
00000350  20 6c 6f 6f 6b 73 0a 66  6f 72 20 64 6f 75 62 6c  | looks.for doubl|
00000360  65 2d 63 6c 69 63 6b 73  20 74 6f 20 69 6e 66 65  |e-clicks to infe|
00000370  63 74 20 61 70 70 6c 69  63 61 74 69 6f 6e 20 64  |ct application d|
00000380  69 72 65 63 74 6f 72 69  65 73 20 28 63 6f 70 69  |irectories (copi|
00000390  65 73 20 74 68 65 20 52  49 53 43 4f 53 65 78 74  |es the RISCOSext|
000003a0  0a 61 6e 64 20 54 61 73  6b 41 6c 6c 6f 63 20 66  |.and TaskAlloc f|
000003b0  69 6c 65 73 20 69 6e 74  6f 20 74 68 65 72 65 20  |iles into there |
000003c0  61 6e 64 20 74 68 65 6e  20 61 70 70 65 6e 64 73  |and then appends|
000003d0  20 74 68 65 20 27 75 73  75 61 6c 27 20 73 74 72  | the 'usual' str|
000003e0  69 6e 67 20 74 6f 20 74  68 65 20 21 42 6f 6f 74  |ing to the !Boot|
000003f0  0a 66 69 6c 65 20 28 74  6f 20 72 75 6e 20 52 49  |.file (to run RI|
00000400  53 43 4f 53 65 78 74 29  2e 0a 0a 54 68 65 20 6e  |SCOSext)...The n|
00000410  61 73 74 79 20 73 65 63  74 69 6f 6e 20 6f 66 20  |asty section of |
00000420  74 68 65 20 54 68 61 6e  61 74 6f 73 20 56 69 72  |the Thanatos Vir|
00000430  75 73 20 52 45 41 4c 4c  59 20 49 53 20 6e 61 73  |us REALLY IS nas|
00000440  74 79 2c 20 73 6f 20 49  20 75 72 67 65 20 79 6f  |ty, so I urge yo|
00000450  75 20 74 6f 0a 73 74 75  64 79 20 74 68 69 73 20  |u to.study this |
00000460  63 61 72 65 66 75 6c 6c  79 2e 20 48 65 72 65 27  |carefully. Here'|
00000470  73 20 61 20 6c 69 73 74  20 6f 66 20 74 68 69 6e  |s a list of thin|
00000480  67 73 20 74 68 61 74 20  63 61 6e 20 68 61 70 70  |gs that can happ|
00000490  65 6e 3a 0a 0a 52 6f 75  67 68 20 6f 6e 63 65 20  |en:..Rough once |
000004a0  65 76 65 72 79 20 31 30  30 30 30 30 20 74 69 6d  |every 100000 tim|
000004b0  65 73 20 61 72 6f 75 6e  64 20 74 68 65 20 57 69  |es around the Wi|
000004c0  6d 70 5f 50 6f 6c 6c 20  6c 6f 6f 70 2c 20 54 68  |mp_Poll loop, Th|
000004d0  61 6e 61 74 6f 73 20 63  61 6e 3a 0a 0a 2a 20 32  |anatos can:..* 2|
000004e0  20 6f 75 74 20 6f 66 20  31 33 20 63 68 61 6e 63  | out of 13 chanc|
000004f0  65 73 3a 20 53 68 75 74  20 64 6f 77 6e 20 69 63  |es: Shut down ic|
00000500  6f 6e 20 62 61 72 20 61  70 70 6c 69 63 61 74 69  |on bar applicati|
00000510  6f 6e 20 61 74 20 72 61  6e 64 6f 6d 20 28 77 68  |on at random (wh|
00000520  69 6c 73 74 0a 20 20 64  69 73 70 6c 61 79 69 6e  |ilst.  displayin|
00000530  67 20 69 74 73 20 6f 77  6e 20 69 63 6f 6e 20 62  |g its own icon b|
00000540  61 72 20 69 63 6f 6e 20  64 75 72 69 6e 67 20 74  |ar icon during t|
00000550  68 65 20 73 68 75 74 64  6f 77 6e 29 2e 0a 0a 2a  |he shutdown)...*|
00000560  20 31 20 6f 75 74 20 6f  66 20 31 33 20 63 68 61  | 1 out of 13 cha|
00000570  6e 63 65 73 3a 20 43 61  75 73 65 20 61 20 44 65  |nces: Cause a De|
00000580  73 6b 74 6f 70 20 51 75  69 74 2e 0a 0a 2a 20 33  |sktop Quit...* 3|
00000590  20 6f 75 74 20 6f 66 20  31 33 20 63 68 61 6e 63  | out of 13 chanc|
000005a0  65 73 3a 20 52 65 76 65  72 73 65 20 74 68 65 20  |es: Reverse the |
000005b0  6d 6f 75 73 65 20 70 6f  69 6e 74 65 72 20 73 74  |mouse pointer st|
000005c0  65 70 20 28 73 65 74 73  20 69 74 20 2d 32 29 2e  |ep (sets it -2).|
000005d0  0a 0a 2a 20 31 20 6f 75  74 20 6f 66 20 31 33 20  |..* 1 out of 13 |
000005e0  63 68 61 6e 63 65 73 3a  20 43 72 61 73 68 20 74  |chances: Crash t|
000005f0  68 65 20 6d 61 63 68 69  6e 65 20 62 79 20 70 6f  |he machine by po|
00000600  6b 69 6e 67 20 61 20 64  75 66 66 20 69 6e 73 74  |king a duff inst|
00000610  72 20 61 74 20 74 68 65  20 73 74 61 72 74 0a 20  |r at the start. |
00000620  20 6f 66 20 6d 65 6d 6f  72 79 2e 0a 0a 2a 20 31  | of memory...* 1|
00000630  20 6f 75 74 20 6f 66 20  31 33 20 63 68 61 6e 63  | out of 13 chanc|
00000640  65 73 3a 20 52 61 6e 64  6f 6d 69 73 65 20 74 68  |es: Randomise th|
00000650  65 20 32 34 30 20 62 79  74 65 73 20 6f 66 20 43  |e 240 bytes of C|
00000660  4d 4f 53 2e 0a 0a 2a 20  34 20 6f 75 74 20 6f 66  |MOS...* 4 out of|
00000670  20 31 33 20 63 68 61 6e  63 65 73 3a 20 52 61 6e  | 13 chances: Ran|
00000680  64 6f 6d 6c 79 20 64 69  73 70 6c 61 79 20 6f 6e  |domly display on|
00000690  65 20 6f 66 20 38 20 76  65 72 79 20 72 75 64 65  |e of 8 very rude|
000006a0  20 6d 65 73 73 61 67 65  73 20 2d 20 6f 6e 65 20  | messages - one |
000006b0  6f 66 0a 20 20 77 68 69  63 68 20 61 6c 73 6f 20  |of.  which also |
000006c0  63 68 61 6e 67 65 73 20  74 68 65 20 6d 6f 75 73  |changes the mous|
000006d0  65 20 70 6f 69 6e 74 65  72 20 73 68 61 70 65 20  |e pointer shape |
000006e0  74 6f 20 61 20 72 75 64  65 20 67 72 61 70 68 69  |to a rude graphi|
000006f0  63 20 61 6e 64 20 61 6e  6f 74 68 65 72 0a 20 20  |c and another.  |
00000700  77 69 6c 6c 20 61 6c 73  6f 20 73 68 75 74 64 6f  |will also shutdo|
00000710  77 6e 20 61 6e 20 69 63  6f 6e 20 62 61 72 20 61  |wn an icon bar a|
00000720  70 70 6c 69 63 61 74 69  6f 6e 20 28 74 68 65 20  |pplication (the |
00000730  73 61 6d 65 20 72 6f 75  74 69 6e 65 20 61 73 20  |same routine as |
00000740  61 62 6f 76 65 29 2e 0a  0a 2a 20 31 20 6f 75 74  |above)...* 1 out|
00000750  20 6f 66 20 31 33 20 63  68 61 6e 63 65 73 3a 20  | of 13 chances: |
00000760  57 69 70 65 20 74 68 65  20 63 6f 6e 74 65 6e 74  |Wipe the content|
00000770  73 20 6f 66 20 3c 4f 62  65 79 24 44 69 72 3e 2e  |s of <Obey$Dir>.|
00000780  0a 0a 49 74 20 61 6c 73  6f 20 68 61 73 20 61 20  |..It also has a |
00000790  22 73 70 65 63 69 61 6c  20 64 61 74 65 22 20 73  |"special date" s|
000007a0  65 63 74 69 6f 6e 20 61  73 20 66 6f 6c 6c 6f 77  |ection as follow|
000007b0  73 3a 0a 0a 41 6e 79 20  46 72 69 64 61 79 20 31  |s:..Any Friday 1|
000007c0  33 74 68 3a 20 41 64 76  65 72 74 69 73 65 73 20  |3th: Advertises |
000007d0  69 74 73 20 6f 77 6e 20  22 76 69 72 75 73 20 6b  |its own "virus k|
000007e0  69 6c 6c 65 72 22 20 28  66 72 6f 6d 20 41 72 6d  |iller" (from Arm|
000007f0  65 6e 20 53 6f 66 74 77  61 72 65 29 2e 0a 0a 41  |en Software)...A|
00000800  70 72 69 6c 20 31 73 74  3a 20 31 30 20 41 64 64  |pril 1st: 10 Add|
00000810  72 65 73 73 20 65 78 63  65 70 74 69 6f 6e 20 65  |ress exception e|
00000820  72 72 6f 72 73 2c 20 66  6f 6c 6c 6f 77 65 64 20  |rrors, followed |
00000830  62 79 20 63 6f 6c 6f 75  72 65 64 20 72 65 63 74  |by coloured rect|
00000840  61 6e 67 6c 65 73 20 61  6e 64 0a 61 20 27 73 74  |angles and.a 'st|
00000850  75 63 6b 27 20 6d 6f 75  73 65 20 70 6f 69 6e 74  |uck' mouse point|
00000860  65 72 20 66 6f 72 20 31  30 20 73 65 63 6f 6e 64  |er for 10 second|
00000870  73 2e 20 41 6e 20 22 41  70 72 69 6c 20 46 6f 6f  |s. An "April Foo|
00000880  6c 22 20 6d 65 73 73 61  67 65 20 69 73 20 74 68  |l" message is th|
00000890  65 6e 0a 64 69 73 70 6c  61 79 65 64 2e 0a 0a 44  |en.displayed...D|
000008a0  65 63 65 6d 62 65 72 20  32 35 74 68 3a 20 44 65  |ecember 25th: De|
000008b0  73 74 72 6f 79 73 20 74  68 65 20 64 69 73 6b 20  |stroys the disk |
000008c0  6d 61 70 20 6f 66 20 41  44 46 53 20 64 72 69 76  |map of ADFS driv|
000008d0  65 73 20 30 2c 20 34 20  61 6e 64 20 35 20 66 6f  |es 0, 4 and 5 fo|
000008e0  6c 6c 6f 77 65 64 20 62  79 0a 61 20 22 4d 65 72  |llowed by.a "Mer|
000008f0  72 79 20 43 68 72 69 6d  62 6c 65 22 20 6d 65 73  |ry Chrimble" mes|
00000900  73 61 67 65 2e 0a 0a 4f  63 74 6f 62 65 72 20 33  |sage...October 3|
00000910  31 73 74 3a 20 46 6f 72  6d 61 74 73 20 74 68 65  |1st: Formats the|
00000920  20 66 6c 6f 70 70 79 20  69 6e 20 64 72 69 76 65  | floppy in drive|
00000930  20 30 2c 20 66 6f 6c 6c  6f 77 65 64 20 62 79 20  | 0, followed by |
00000940  61 20 22 53 70 6f 6f 6b  79 22 20 6d 65 73 73 61  |a "Spooky" messa|
00000950  67 65 2e 0a 0a 4a 61 6e  75 61 72 79 20 31 73 74  |ge...January 1st|
00000960  3a 20 41 73 20 44 65 63  65 6d 62 65 72 20 32 35  |: As December 25|
00000970  74 68 2c 20 62 75 74 20  66 6f 6c 6c 6f 77 65 64  |th, but followed|
00000980  20 62 79 20 61 20 4e 65  77 20 59 65 61 72 27 73  | by a New Year's|
00000990  20 52 65 73 6f 6c 75 74  69 6f 6e 0a 6d 65 73 73  | Resolution.mess|
000009a0  61 67 65 20 28 74 6f 20  6b 65 65 70 20 79 6f 75  |age (to keep you|
000009b0  72 20 64 69 73 6b 73 20  77 72 69 74 65 2d 70 72  |r disks write-pr|
000009c0  6f 74 65 63 74 65 64 20  3a 2d 28 20 29 2e 0a 0a  |otected :-( )...|
000009d0  4b 69 6c 6c 69 6e 67 20  74 68 65 20 54 68 61 6e  |Killing the Than|
000009e0  61 74 6f 73 20 56 69 72  75 73 20 28 77 68 69 63  |atos Virus (whic|
000009f0  68 20 6f 6e 65 20 3f 3f  29 0a 2d 2d 2d 2d 2d 2d  |h one ??).------|
00000a00  2d 2d 2d 2d 2d 2d 2d 2d  2d 2d 2d 2d 2d 2d 2d 2d  |----------------|
00000a10  2d 2d 2d 2d 0a 0a 54 68  65 72 65 20 61 70 70 65  |----..There appe|
00000a20  61 72 73 20 74 6f 20 62  65 20 2a 54 57 4f 2a 20  |ars to be *TWO* |
00000a30  76 65 72 73 69 6f 6e 73  20 6f 66 20 74 68 65 20  |versions of the |
00000a40  54 68 61 6e 61 74 6f 73  20 56 69 72 75 73 20 2d  |Thanatos Virus -|
00000a50  20 6f 6e 65 20 77 69 74  68 20 64 65 62 75 67 67  | one with debugg|
00000a60  69 6e 67 0a 52 45 4d 20  73 74 61 74 65 6d 65 6e  |ing.REM statemen|
00000a70  74 73 20 28 75 73 75 61  6c 6c 79 20 77 69 74 68  |ts (usually with|
00000a80  20 74 68 65 20 73 74 72  69 6e 67 20 22 2a 64 62  | the string "*db|
00000a90  67 2a 22 20 69 6e 20 74  68 65 6d 29 20 61 6e 64  |g*" in them) and|
00000aa0  20 6f 6e 65 20 77 69 74  68 6f 75 74 2e 0a 48 6f  | one without..Ho|
00000ab0  77 65 76 65 72 2c 20 62  6f 74 68 20 61 70 70 65  |wever, both appe|
00000ac0  61 72 20 74 6f 20 62 65  20 69 64 65 6e 74 69 63  |ar to be identic|
00000ad0  61 6c 20 69 6e 20 66 75  6e 63 74 69 6f 6e 2c 20  |al in function, |
00000ae0  73 6f 20 49 27 76 65 20  74 72 65 61 74 65 64 20  |so I've treated |
00000af0  74 68 65 6d 20 62 6f 74  68 0a 61 73 20 74 68 65  |them both.as the|
00000b00  20 73 61 6d 65 20 76 69  72 75 73 2e 20 54 6f 20  | same virus. To |
00000b10  6b 69 6c 6c 20 74 68 65  6d 2c 20 73 69 6d 70 6c  |kill them, simpl|
00000b20  79 20 73 65 6e 64 69 6e  67 20 61 20 4d 65 73 73  |y sending a Mess|
00000b30  61 67 65 5f 51 75 69 74  20 74 6f 20 74 68 65 20  |age_Quit to the |
00000b40  57 69 6d 70 20 54 61 73  6b 0a 69 73 6e 27 74 20  |Wimp Task.isn't |
00000b50  67 6f 6f 64 20 65 6e 6f  75 67 68 20 28 63 6f 6d  |good enough (com|
00000b60  65 73 20 62 61 63 6b 20  77 69 74 68 20 61 20 72  |es back with a r|
00000b70  75 64 65 20 6d 65 73 73  61 67 65 20 69 66 20 79  |ude message if y|
00000b80  6f 75 20 64 6f 29 2e 20  56 4b 69 6c 6c 65 72 20  |ou do). VKiller |
00000b90  6d 6f 64 69 66 69 65 73  0a 74 68 65 20 42 41 53  |modifies.the BAS|
00000ba0  49 43 20 70 72 6f 67 72  61 6d 20 28 22 69 6e 20  |IC program ("in |
00000bb0  73 69 74 75 22 29 20 74  6f 20 71 75 69 74 20 70  |situ") to quit p|
00000bc0  72 6f 70 65 72 6c 79 20  2d 20 61 66 74 65 72 20  |roperly - after |
00000bd0  63 68 65 63 6b 69 6e 67  20 77 68 65 74 68 65 72  |checking whether|
00000be0  20 69 74 20 69 73 0a 74  68 65 20 27 64 65 62 75  | it is.the 'debu|
00000bf0  67 27 20 76 65 72 73 69  6f 6e 20 6f 72 20 6e 6f  |g' version or no|
00000c00  74 2e 0a 0a 4d 79 20 63  6f 70 79 20 6f 66 20 74  |t...My copy of t|
00000c10  68 65 20 54 68 61 6e 61  74 6f 73 20 76 69 72 75  |he Thanatos viru|
00000c20  73 20 68 61 73 20 61 20  6d 61 6a 6f 72 20 66 61  |s has a major fa|
00000c30  75 6c 74 20 2d 20 69 74  20 75 73 65 73 20 74 68  |ult - it uses th|
00000c40  65 20 45 4e 44 3d 3c 65  78 70 72 65 73 73 69 6f  |e END=<expressio|
00000c50  6e 3e 0a 73 79 6e 74 61  78 20 74 6f 20 61 64 6a  |n>.syntax to adj|
00000c60  75 73 74 20 42 41 53 49  43 27 73 20 6d 65 6d 6f  |ust BASIC's memo|
00000c70  72 79 20 75 73 61 67 65  2c 20 62 75 74 20 67 69  |ry usage, but gi|
00000c80  76 65 73 20 74 6f 6f 20  6c 6f 77 20 61 20 76 61  |ves too low a va|
00000c90  6c 75 65 20 2d 20 68 65  6e 63 65 20 69 74 0a 6e  |lue - hence it.n|
00000ca0  65 76 65 72 20 72 75 6e  73 20 70 72 6f 70 65 72  |ever runs proper|
00000cb0  6c 79 20 28 69 6d 6d 65  64 69 61 74 65 6c 79 20  |ly (immediately |
00000cc0  63 72 61 73 68 65 73 20  77 69 74 68 20 22 4e 6f  |crashes with "No|
00000cd0  20 72 6f 6f 6d 20 66 6f  72 20 74 68 69 73 20 44  | room for this D|
00000ce0  49 4d 22 20 65 72 72 6f  72 29 2e 0a 46 6f 72 20  |IM" error)..For |
00000cf0  70 75 72 70 6f 73 65 73  20 6f 66 20 74 65 73 74  |purposes of test|
00000d00  69 6e 67 2c 20 49 20 62  6f 6f 73 74 65 64 20 74  |ing, I boosted t|
00000d10  68 65 20 45 4e 44 20 76  61 6c 75 65 20 28 6f 6e  |he END value (on|
00000d20  20 74 68 65 20 61 73 73  75 6d 70 74 69 6f 6e 20  | the assumption |
00000d30  74 68 61 74 20 74 68 65  0a 76 69 72 75 73 20 61  |that the.virus a|
00000d40  75 74 68 6f 72 20 77 6f  75 6c 64 20 65 76 65 6e  |uthor would even|
00000d50  74 75 61 6c 6c 79 20 66  69 78 20 74 68 69 73 20  |tually fix this |
00000d60  6d 69 73 74 61 6b 65 29  2e 0a 0a 54 68 61 6e 61  |mistake)...Thana|
00000d70  74 6f 73 20 56 69 72 75  73 20 49 6e 6e 6f 63 75  |tos Virus Innocu|
00000d80  6c 61 74 69 6f 6e 0a 2d  2d 2d 2d 2d 2d 2d 2d 2d  |lation.---------|
00000d90  2d 2d 2d 2d 2d 2d 2d 2d  2d 2d 2d 2d 2d 2d 2d 2d  |----------------|
00000da0  2d 2d 0a 0a 54 65 6d 70  6f 72 61 72 79 20 69 6e  |--..Temporary in|
00000db0  6e 6f 63 75 6c 61 74 69  6f 6e 20 63 61 6e 20 62  |noculation can b|
00000dc0  65 20 61 63 68 69 65 76  65 64 20 62 79 20 73 65  |e achieved by se|
00000dd0  74 74 69 6e 67 20 53 79  73 24 50 61 74 68 20 74  |tting Sys$Path t|
00000de0  6f 20 61 6e 79 20 76 61  6c 75 65 0a 28 56 4b 69  |o any value.(VKi|
00000df0  6c 6c 65 72 27 73 20 21  42 6f 6f 74 20 6e 6f 77  |ller's !Boot now|
00000e00  20 64 6f 65 73 20 74 68  69 73 29 2c 20 62 65 63  | does this), bec|
00000e10  61 75 73 65 20 74 68 69  73 20 69 73 20 63 68 65  |ause this is che|
00000e20  63 6b 65 64 20 62 79 20  74 68 65 20 54 68 61 6e  |cked by the Than|
00000e30  61 74 6f 73 0a 56 69 72  75 73 20 74 6f 20 73 65  |atos.Virus to se|
00000e40  65 20 69 66 20 69 74 20  69 73 20 61 6c 72 65 61  |e if it is alrea|
00000e50  64 79 20 70 72 65 73 65  6e 74 20 69 6e 20 74 68  |dy present in th|
00000e60  65 20 73 79 73 74 65 6d  2e 20 50 65 72 6d 61 6e  |e system. Perman|
00000e70  65 6e 74 20 69 6e 6e 6f  63 75 6c 61 74 69 6f 6e  |ent innoculation|
00000e80  0a 69 73 20 6e 6f 74 20  70 6f 73 73 69 62 6c 65  |.is not possible|
00000e90  2e 0a                                             |..|
00000e92

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