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RE: [WEB SECURITY] Cross Site Scripting

From: "Sergii Khomenko" <sergey.khomenko@xxxxxxxxx>
Subject: RE: [WEB SECURITY] Cross Site Scripting
Date: Thu, 20 Sep 2007 18:45:08 +0300
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To reduce the risk and to prevent such an attack on your website, all =
form information that is entered, should be checked for html code like =
this <script>script code goes here</script>. Basically, your website =
should not accept any script code from anyone on the web and especially =
storing the code in the db and then outputting it to somebody else.

=20

When you add validation for your input fields, you can run free web =
vulnarability scanners like www.acunetix.com <http://www.acunetix.com/>  =
to see if you still have the vulns.

=20

Hope this helps.

=20

Sergii Khomenko

=20

  _____ =20

From: Mad Unix [mailto:madunix@gmail.com]=20
Sent: Thursday, September 20, 2007 10:53 AM
To: websecurity@webappsec.org
Subject: [WEB SECURITY] Cross Site Scripting

=20

Our security consulting compay he discoverd on our web server the =
following risk:

=20

Cross Site Scripting=20
Risk: High

Description of Vulnerability

The Cross-Site Scripting attack is a privacy violation that allows an =
attacker to acquire a legitimate user's=20
credentials and to impersonate that user when interacting with a =
specific website.=20
The attack hinges on the fact that the web site contains a script that =
returns a user's input=20
(usually a parameter value) in an HTML page, without first sanitizing =
the input.=20
This allows an input consisting of JavaScript code to be executed by the =
browser when the script returns this input=20
in the response page. As a result, it is possible to form links to the =
site where one of the parameters consists of malicious=20
 JavaScript code. This code will be executed (by a user's browser) in =
the site context, granting=20
it access to cookies that the user has for the site, and other windows =
in the site through the user's browser.=20

=20

=20

--------------

Can any one tell me more about this effect and how to observe and =
resolve this issue, since is be given as high risk.

Thanks



--=20
madunix

madunix@gmail.com=20


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<head>
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<div class=3DSection1>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>To reduce the =
risk and to
prevent such an attack on your website, all form information that is =
entered,
should be checked for html code like this &lt;script&gt;script code goes =
here&lt;/script&gt;.
Basically, your website should not accept any script code from anyone on =
the
web and especially storing the code in the db and then outputting it to
somebody else.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p>=
</span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>When you add =
validation for
your input fields, you can run free web vulnarability scanners like <a
href=3D"http://www.acunetix.com/";>www.acunetix.com</a> to see if you =
still have
the vulns.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p>=
</span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>Hope this =
helps.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p>=
</span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Arial;color:navy'>Sergii =
Khomenko<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p>=
</span></font></p>

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0cm 4.0pt'>

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size=3D3
face=3D"Times New Roman"><span lang=3DEN-US style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span lang=3DEN-US
style=3D'font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</spa=
n></font></b><font
size=3D2 face=3DTahoma><span lang=3DEN-US =
style=3D'font-size:10.0pt;font-family:Tahoma'>
Mad Unix [mailto:madunix@gmail.com] <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Thursday, September =
20, 2007
10:53 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> =
websecurity@webappsec.org<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> [WEB SECURITY] =
Cross Site
Scripting</span></font><span lang=3DEN-US><o:p></o:p></span></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>Our&nbsp;security consulting compay he discoverd on our web =
server the
following risk:<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>Cross Site Scripting <br>
Risk: High<o:p></o:p></span></font></p>

</div>

<p><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'>Description
of Vulnerability<o:p></o:p></span></font></p>

<p><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'>The
Cross-Site Scripting attack is a privacy violation that allows an =
attacker to
acquire a legitimate user's <br>
credentials and to impersonate that user when interacting with a =
specific
website. <br>
The attack hinges on the fact that the web site contains a script that =
returns
a user's input <br>
(usually a parameter value) in an HTML page, without first sanitizing =
the input.
<br>
This allows an input consisting of JavaScript code to be executed by the
browser when the script returns this input <br>
in the response page. As a result, it is possible to form links to the =
site
where one of the parameters consists of malicious <br>
&nbsp;JavaScript code. This code will be executed (by a user's browser) =
in the
site context, granting <br>
it access to cookies that the user has for the site, and other windows =
in the
site through the user's browser. <o:p></o:p></span></font></p>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>--------------<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>Can any one tell me more about this effect and how to observe =
and
resolve this issue, since is be given as high =
risk.<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>Thanks<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><br clear=3Dall>
<br>
-- <br>
madunix<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><a =
href=3D"mailto:madunix@gmail.com";>madunix@gmail.com</a>&nbsp;<o:p></o:p><=
/span></font></p>

</div>

</div>

</div>

</body>

</html>

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Follow-Ups:
- Re: [WEB SECURITY] Cross Site Scripting
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- RE: [WEB SECURITY] Cross Site Scripting
  - From: Hoffman, Billy
References:
- [WEB SECURITY] Cross Site Scripting
  - From: Mad Unix
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