Re: Thanks for arch advice - see my photos here

Discussion in 'Computer Security' started by Nehmo Sergheyev, Jul 30, 2003.

  1. Nehmo Sergheyev
    > > An attachment ending with "JPG" is just a pic.


    Michael Shields
    > An attachment or link with a name ending in "jpg" may actually have a
    > content-type of anything. It might not be a JPEG picture at all; it
    > is possible for it to be an HTML page, an executable, or anything.


    Nehmo
    I would think the newsreader somehow has to know what to do with a file
    once it gets it. I assume it looks at the extension and then opens it or
    sends it to another program. Certain extensions and security settings
    may cause a warning to pop up.

    I would also thing if Outlook Express saw the .jpg extension on a link,
    it would get Internet Explorer to render it into a pic.

    I don't know how a .jpg can execute. I crossposted this in the hope of
    getting an answer.
    [The thread started in news:alt.building.construction.]

    Is it always safe to click on a .jpg?







    --
    *******************
    * Nehmo Sergheyev *
    *******************
    http://home.kc.rr.com/missouri/Susan_Talks.htm
     
    Nehmo Sergheyev, Jul 30, 2003
    #1
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  2. Nehmo
    > > I would think the newsreader somehow has to know what to do with a

    file
    > > once it gets it. I assume it looks at the extension and then opens

    it or
    > > sends it to another program.


    Michael Shields
    > Not so. The web server sends a "content-type" along with each file it
    > serves. Usually it sends "image/jpeg" along with a file that ends in
    > ".jpg", but it could be configured to send anything.


    Nehmo
    Well, Okay. where would this "content-type" thing be?

    Nehmo
    > > Is it always safe to click on a .jpg?


    Michael
    > No. If you don't trust your browser or mailer or newsreader to keep
    > you safe from external content, you should get one that you do trust.


    Nehmo
    I know from experience that I'm probably not safe. But I still wouldn't
    hesitate to click on a jpg.

    You're not specific with your recommendations.





    --
    *******************
    * Nehmo Sergheyev *
    *******************
    http://home.kc.rr.com/missouri/Susan_Talks.htm
     
    Nehmo Sergheyev, Jul 31, 2003
    #2
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  3. Nehmo Sergheyev

    Jim Watt Guest

    On Thu, 31 Jul 2003 17:16:14 GMT, "Nehmo Sergheyev"
    <> wrote:

    >I know from experience that I'm probably not safe. But I still wouldn't
    >hesitate to click on a jpg.


    As long as it really is a .jpg

    One of the trick of the worms is to sent attachments of the form

    nice_photo.jpg.scr

    which is in fact executable.
    --
    Jim Watt http://www.gibnet.com
     
    Jim Watt, Jul 31, 2003
    #3
  4. Nehmo
    > >I know from experience that I'm probably not safe. But I still

    wouldn't
    > >hesitate to click on a jpg.


    Jim Watt
    > As long as it really is a .jpg
    > One of the trick of the worms is to sent attachments of the form
    > nice_photo.jpg.scr
    > which is in fact executable.


    Nehmo
    Another trick I've seen is put the innocuous jpg letters and then to put
    a whole bunch of spaces right before the real file extension, hopefully
    tricking the clicker into missing the real extension.
    Girlslickinggirls.jpg___________________________________.vbs








    --
    *******************
    * Nehmo Sergheyev *
    *******************
    http://home.kc.rr.com/missouri/Susan_Talks.htm
     
    Nehmo Sergheyev, Jul 31, 2003
    #4
  5. In article <y9cWa.807$>,
    "Nehmo Sergheyev" <> wrote:
    > Well, Okay. where would this "content-type" thing be?


    It's sent by the web server along with the file. In Netscape or
    Mozilla, you can right-click and select "View Page Info" to see the
    types of the page ("text/html") and its images (for example
    "image/gif").

    > I know from experience that I'm probably not safe. But I still wouldn't
    > hesitate to click on a jpg.


    A URL ending in ".jpg" may not actually be a JPEG image. It could
    potentially be anything. There is no way to be safe; if your browser
    is going to execute active content when it finds it, then eventually
    it will, because active content could be at any URL.

    > You're not specific with your recommendations.


    Instead of avoiding attachments and links, get a browser that won't
    ever run executables without your explicit permission. Then you won't
    need to worry about what to click on. If your current browser is
    insecure, complain.
    --
    Shields.
     
    Michael Shields, Aug 1, 2003
    #5
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