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malicious computer program

Posted on 2004-03-21
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Last Modified: 2008-03-10
A malicious computer program - perhaps a virus, I guess - informs a user that is hass "kidnapped" an important file and that what happens to the file will depend on the next statement typed by the user:

 - If the user types a false statement, the file will be deleted permanetly.

 - If the user types a true statement, the file will be randomly renamed and hidden in some obscured sub-directory, so that it can never be found and used again.

 - Failure to enter a statement would result in the deletion of that and many other files.

{Ignore the obvious problem of how the program can determine truth!}

Furthermore, the statement must fulfill several conditions. It must:

 - consist of a complete sentence [of any number of words];
 - be empirical [that is, it must refer to observable, measurable reality];
 - be related in some way to the program's threatened destructive or modification of the file.

The user typed a statement consisted with the condition listed above; the file was left unchanged, undeleted, with the same name.

What statement could the user have typed? [There are probably many statements which would work, differing in thier specific wording, but all recognizably members of the same family of statement.]


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Question by:diddo143
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by:Wwysdom
ID: 10646577
This file will be deleted permanently.
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by:HippyWarlock
ID: 10646711
Run Norton Ghost or similiar first, then just compare the two file listings, the extra file is yours - easy eh?

Peace
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by:HippyWarlock
ID: 10646734
I assume the wastebin gets emptied too

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by:HippyWarlock
ID: 10646762
Statement 1 : >The below statement is true.
Statement 2 : >The above statement is false.

cue infinite loop

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by:ArcaArtem
ID: 10646943
Statement> You have kidnapped yourself you idoot!

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by:Wwysdom
ID: 10647128
As they used to say in the lounge...
Just fdisk and format.

d:D
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by:☠ MASQ ☠
ID: 10647161
Logic bomb!

>>My important file will be deleted<<

If the deletion happens as a result then the statement is true and the virus cannot delete the file.  If the file is then renamed by the virus the statement becomes false.

If the file is not deleted the statement is false & the virus should have deleted the file but did not.
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by:☠ MASQ ☠
ID: 10647165
(Points are Wwysdom's - they were in first!)
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by:HippyWarlock
ID: 10648131
I'm still waiting for my loop to be resolved :-/

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by:see201
ID: 10649205
The user unplugs the computer.  Problem solved!
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by:see201
ID: 10649232
The user types the words "a statement".  As per the rules, failure to do otherwise will result in the deletion of that and many other files.  The important file will not be deleted because the user didn't type "a false statement", and it won't be renamed because the user didn't type "a true statement".
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by:Mercantilum
ID: 10650946
"You will delete my important file but not hide it in some obscured sub-directory!"
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by:diddo143
ID: 10653158
Mercantilum, why would that work??? please explain.

See01, I thought the same thing but then I read on and your answer may vary so that answer really can't vary so I don't think that is right.

MASQUERAID, your explaination is very confusing it sounds like it makes sence but I am not sure if I am reading it right.

Wwysdom, please explain.

Thanks everyone for helping me out!!
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☠ MASQ ☠ earned 125 total points
ID: 10653475
>>My important file will be deleted<<

It works because the virus follows a fixed logic.

If the statement is false then the file will be deleted.  But this would mean that the statement above becomes true.  The virus cannot action this.  Result inaction - the file is left alone.

If the statement is true the the file will not be deleted (moved instead).  But this would mean that the statement above becomes false.  The virus cannot action this.  result inaction - the file is left alone.
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by:☠ MASQ ☠
ID: 10653501
@ HippyWarlock

^C
Break at line 210
>_

Now you can relax!
Hope this helps!

M :o)
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by:Wwysdom
ID: 10653713
Well, since dear MASQUERAID has explained it so well...
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by:Mercantilum
ID: 10654807
"You will delete my important file but not hide it in some obscured sub-directory!", explanation:

1. if it is false, the file should be deleted - but the sentance says "you will delete my important files", so if the file is deleted, the sentance was actually true
    => the sentance is not logically resolvable if it was said as false initially

2. if it is true, the file will be hidden, but the sentance says " not hide my file" so, again, it cannot be true either
    => the sentance is not logically resolvable if it was said as true initially

The virus attemps to do an action but it cannot assess the sentance as true, neither false.
So it does nothing.
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by:Wwysdom
ID: 10655011
This file will be deleted permanently.

If True, the virus should delete the file, but since the condition is that all true statements will result in the file being randomly hidden, this makes the statement false.

If False, the condition is that the file will be deleted permanently, but this will make the statement true, as it is correctly stated in the statement.

Since a sentence cannot be both true and false at the same time, the virus will not know what to do. At worst, it will just crash your whole system as it will use up all memory and resources in trying to find out which action to take.

PS. A small note: Both MASQUERAID's and Mercantilum's answers have the same logic, but their statements do not specifically refer to which file they refer to...

d:D
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by:HippyWarlock
ID: 10655222
Chhers masq - I ran it on a Cray - it's well known that a corrctly configured HyperComputer can finish an infinite FOR-NEXT loop in just under an hour.


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by:ozo
ID: 10655286
Why should we believe a malicious virus is telling the truth about what it's going to do with a file?
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Author Comment

by:diddo143
ID: 10657846
I'm sorry guys I was going to spllit the points  but I messed up. Thank you for all your help.  Sorry again.
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by:☠ MASQ ☠
ID: 10659964
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by:diddo143
ID: 10662086
I'm sorry Wwysdom I was going to give you mostof the points and give MASQUERAID some and I thought you could split the points but I guess I messed up. I am really sorry about that.
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