[Full-disclosure] Yahoo mail Cross Site Scripting vulnerability
simo at morx.org
simo at morx.org
Sun Dec 25 18:00:29 GMT 2005
Title: Yahoo mail Cross Site Scripting
Author: Simo Ben youssef aka _6mO_HaCk <simo_at_morx_org>
Date: 22 December 2005
MorX Security Research Team
Vendor: Yahoo mail, and possibly others
Vulnerability: Cross Site Scripting / Cookie-Theft / Relogin attacks
Tested on: Microsoft IE 6.0
Yahoo mail filter fails to detect script attributes in combination with
the style attribute as a tag, leaving everyone using yahoo mail service
with MSIE vulnerable to Cross Site Scripting including Cookie Theft and
relogin attacks. This is a high risk security vulnerability because the
attacker wont have to make the victim click on any link, all he/she has
once the victim open the email the malicious code will be executed in
an attacker can send the infiltred code as an html email to a yahoo mail
content will be executed in the the target browser. This will allow user's
session cookie theft, giving the attacker access to the victim mail box
for about 24 hours (until the cookie expires) and also other types of
attacks like reloging.
Exemple of Exploit code:
<STYLE onload="alert('Yahoo mail ! cookies exploit by _6mO_HaCk, click OK
now to view your cookie ;)'); alert(document.cookie)"> </STYLE>
Switch to firefox, or disable script execution
i didnt contact yahoo, because i contacted them previously regarding a
similar vulnerability, and yes they fixed it "silently" without even
sending me a thank you email, frankly i didnt really appreciate that.
this entire document is for eductional, testing and demonstrating purpose
only. Modification use and/or publishing this information is entirely on
your OWN risk. The exploit code is to be used on your OWN email account. I
cannot be held responsible
for any of the above.
Yahoo is vulnerable to others similar vulnerabilites, that was just one
exemple of many, demonstrating how it's easy to bypass webmail filters,
for more information or details please contact me at simo_at_morx_org.
merry christmas everybody and happy new year. if you like this advisory
then buy me a blue motherfuc*er next saturday on Alumni club, Schaumburg,
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