Cross Site Scripting (XSS) Vulnerability in Web Mail service by "Walla! Communications LTD"
·= Security Advisory =·
Issue: Cross Site Scripting (XSS) Vulnerability in Web Mail service by
"Walla! Communications LTD"
Discovered Date: 05/10/2006
Author: 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/Filtering
of 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
presentation
of a document written in a markup language. Its most common application is
to style web pages written
in 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 to
other properties on the current page. Array references are not allowed on
object
properties included in this script.
<ELEMENT STYLE="AttributeName:expression(Script)">
Exploitation Mail:
...
------=_NextPart_000_0006_01C6DD9E.26B2BBD0
Content-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 exploited
to 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, CEH
www.zion-security.com