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How does a virus know if it has allready infected a file?

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By Jskid
Aug 31, 2010
  1. How does a virus know if it has already infected a file? If it doesn't then it will continually infect the same files until they corrupt.
     
  2. Bobbye

    Bobbye Helper on the Fringe Posts: 16,392   +36

    It doesn't. A virus isn't written to infect a file or corrupt it. The infection or corruption is the result of the virus, not the intent. See http://en.wikipedia.org/wiki/Computer_virus

    Just a small Edit: You may come across the term 'file infector' which will sound contrary to what I have said. So read the entire description to better understand.
     
  3. Jskid

    Jskid TS Enthusiast Topic Starter Posts: 433

    Doesn't the article contradict itself? It first says that a true virus must spread itself and then it says a virus is different from a trojan because a trojan has a mechanism for spreading. Also in the article on trojans it says "Unlike a virus, it[a trojan] does not need to attach itself to an existing program" which suggests that all viruses infect. Sorry for being slow.

    When a "virus infects a file system or computer" that just means a virus has been executed on the computer, right?
     
  4. Bobbye

    Bobbye Helper on the Fringe Posts: 16,392   +36

    No, using the word 'executes' here for a general description, is inaccurate. The Webopedia definition of 'execute is:
    "(v.) Same as run, to perform an action, as in executing a program or a command."

    For instance, Virut is a Polymorphic File Infector that infects ..exe, .scr, .rar, .zip, .htm, .html.
    It specifically uses exe or executable files as a means of spreading their infection.

    Some people use the term "caught a virus", relating a computer infection to a human one. Your original question was how does a virus know it's infected all the files. If you want a very general answer to that, and it would depend on the actual virus, I'd have to say if a virus causes enough files to become corrupt because of it's actions and the system crashes, there won't be any system left for it to work on!

    If you do over the information on the site I left, you might better understand that the way a malware infection works will depend on what it was written to do. Some malware isn't going to harm files and folders on the host computer if it's a 'backdoor' to be used to either or both access the computer from the internet and to transmit from the computer to the internet.
     
  5. Jskid

    Jskid TS Enthusiast Topic Starter Posts: 433

    So for example how does Virut know if has already infected a file? Does it keep a list of infected files or something?
     
  6. Jskid

    Jskid TS Enthusiast Topic Starter Posts: 433

    "Unlike a virus, it does not need to attach itself to an existing program" -wikipedia
    this implies that all virus are file infectors?
     
  7. Bobbye

    Bobbye Helper on the Fringe Posts: 16,392   +36

    Please read: http://www.virusbtn.com/resources/glossary/file_infector_virus.xml

    Since you have failed to define the point you are trying to make and since references for information on the action of viruses have been provided, I do not think there is any point in continuing this thread. However, you are free to search on your own for anything that may satisfy some point you are attempting to make.
     
  8. Bobbye

    Bobbye Helper on the Fringe Posts: 16,392   +36

    Please read: http://www.virusbtn.com/resources/glossary/file_infector_virus.xml

    Since you have failed to define the point you are trying to make and since references for information on the action of viruses have been provided, I do not think there is any point in continuing this thread. However, you are free to search on your own for anything that may satisfy some point you are attempting to make.

    I note that you are a new Member and have other posts on the board, so I reviewed some of them. You asked questions that were answered, then you consistently tried to change the wording of what you were given using the phrase "is equivalent to saying."

    On one thread you had the comment
    This would seemingly indicate that you are pirating programs.

    We try very hard to answer questions, give recommendations, clean malware and a multitude of other computer related information. But when someone consistently drops off a thread, consistently fails to say 'thank you' and consistently argues a point, it would seem that that matter would come under the grouping of jerking around.
     
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