·= Security Advisory =·
Issue: Cross Site Scripting (XSS) Vulnerability in Web Mail service by "Walla!
Communications LTD"Discovered Date: 05/10/2006Author: Tal Argoni,
LegendaryZion. [talargoni at gmail.com]Product Vendor: http://www.walla.co.il/
Details:
Walla! Communications LTD Web Mail service is prone to a Cross Site Scripting
Vulnerability.The vulnerability exists in filter engine, caused by the lack of
Input Validation/Filteringof malicious Method "Expression()" of Cascading Style
Sheets (CSS).
About Cascading Style Sheets (CSS):
Cascading Style Sheets (CSS) is a stylesheet language used to describe the
presentationof a document written in a markup language. Its most common
application is to style web pages writtenin HTML and
XHTML.English:http://en.wikipedia.org/wiki/Cascading_Style_Sheets
About Expression() Method:
Receive string that specifies any valid script(JScript, JavaScript,
VBSCript)statement without quotations or semicolons. This string can include
references toother properties on the current page. Array references are not
allowed on objectproperties included in this script.
<ELEMENT STYLE="AttributeName:expression(Script)">
Exploitation Mail:
...------=_NextPart_000_0006_01C6DD9E.26B2BBD0Content-Type: text/html;
<IMG width="0" height="0" style="width: expression(alert('expression'));">...
Successful exploitation may allow execution of script code. This could also be
exploitedto spoof the entire website's content, stealing cookies, stealing
session ID,commit Denial Of Service attacks and more...
Proof Of Concept:
<IMG style="width: expression(alert('expression'));">
Thanks,Tal Argoni, CEHwww.zion-security.com
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