The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Title:
======
Skype Account Service - Reset (Session) Password/Username Vulnerability
Date:
=====
2012-11-16
References:
===========
http://www.vulnerability-lab.com/get_content.php?id=720
MSRC ID: 13050[bc]
News:
http://news.softpedia.com/news/Skype-0Day-Vulnerability-Allowed-Hackers-to-Change-the-Password-of-Any-Account-Video-307672.shtml
http://www.scmagazine.com.au/News/323271,skype-account-hijack-hole-patched.aspx
VL-ID:
=====
720
Common Vulnerability Scoring System:
====================================
9.5
Introduction:
=============
Skype is a proprietary voice-over-Internet Protocol service and software application originally created in 2003 by Swedish entrepreneur
Niklas ZennstrÃm and his Danish partner Janus Friis. It has been owned by Microsoft since 2011. The service allows users to communicate
with peers by voice, video, and instant messaging over the Internet. Phone calls may be placed to recipients on the traditional telephone
networks. Calls to other users within the Skype service are free of charge, while calls to landline telephones and mobile phones are charged
via a debit-based user account system. Skype has also become popular for its additional features, including file transfer, and videoconferencing.
Competitors include SIP and H.323-based services, such as Linphone, as well as the Google Talk service, Mumble and Hall.com.
Skype has 663 million registered users as of September 2011. The network is operated by Microsoft, which has its Skype division headquarters
in Luxembourg. Most of the development team and 44% of the overall employees of the division are situated in Tallinn and Tartu, Estonia.
Unlike most other VoIP services, Skype is a hybrid peer-to-peer and clientserver system. It makes use of background processing on computers
running Skype software. Skype`s original proposed name (Sky Peer-to-Peer) reflects this fact. Some network administrators have banned Skype
on corporate, government, home, and education networks, citing reasons such as inappropriate usage of resources, excessive bandwidth usage,
and security concerns.
(Copy of the Vendor Homepage: http://en.wikipedia.org/wiki/Skype)
Abstract:
=========
The Vulnerability Laboratory Research Team discovered a critical session vulnerability in Microsofts Skype Account Service Application.
Report-Timeline:
================
2012-10-01:Researcher Notification & Coordination (VL - Benjamin Kunz Mejri)
2012-10-11:Vendor Notification (Skype Security)
2012-10-11:Vendor Notification (MSRC)
2012-10-23:Vendor Response/Feedback (MSRC)
2012-11-12:Vendor Fix/Patch *Hotfix (Skype)
2012-11-16:Public Disclosure (Vulnerability Laboratory)
Status:
========
Published
Affected Products:
==================
Microsoft
Product: Skype Application & Software Account Service 2012 Q3
Exploitation-Technique:
=======================
Remote
Severity:
=========
Critical
Details:
========
A critical Password Reset (session) vulnerability is detected in Microsofts Skype WebServer Auth System Application. The vulnerability allows remote attackers without privileged application account to exchange and reset any skype account.
The critical application vulnerability is located in the recovery account function of the skype account service application. In the recovery function is an auth request bound to the account session using the json form with jquery and the value of the intercape.
The request itself is not sanitized. The value only check if exist and if empty but not validate the context again. The attacker can bypass the token protection via live session tamper to reset any account by exchanging the values local to his own. Exploitation requires `processing to request` via jquery implement JSon form request. Since yet it is only manually possible to exploit the remote vulnerability by using a session tamper tools like tamper data. A remote attacker can, for example bypass the token protection with values like */+[New Account Details] or [New Account Details]+/* to reset random skype application accounts or infiltrate specific choosen account by changing usernames or passwords.
Successful exploitation of the critical remote vulnerability result in skype account compromise, skype account infiltration, mail information disclosure or lead to skype user account manipulation.
Vulnerable Service(s):
[+] Microsoft - Skype Service - https://login.skype.com/
Vulnerable Section(s):
[+] Account Application Service - https://login.skype.com/account
Vulnerable Module(s):
[+] Recovery Function - https://login.skype.com/account/password-automation
Vulnerable Module(s):
[+] JSon & jquery
Proof of Concept:
=================
The vulnerability can be exploited by remote attacker without required user inter action.
For demonstration or reproduce ...
Required for Exploitation:
[+] Tamper Data or other live tamper software
[+] Web Browser like mozilla firefox, ie9 or chrome
[+] A random registered skype user account to get a not expired session
Exploitation Techique(s):
[+] Bypass the Skype Recovery Page (request tamper) to New Pass or Reset
[+] Bypass token protection via not empty value with positiv value(s) to match
[+] Hold the request via tamper include own values to setup the new password
Next Step(s):
[+] Decode captcha & send automatique value(s) -> Account Service (Remote Exploit)
Reference(s):
[+] https://login.skype.com/account/password-automation
Video(PoC Demo):
[+] http://www.youtube.com/watch?v=RPTEaJftNw0
Solution:
=========
2012-11-12:Vendor Fix/Patch (Skype)
Risk:
=====
The security risk of the remote password and username reset (session) vulnerability is estimated as critical.
Credits:
========
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri ([email protected])
Vulnerability Laboratory [Research Team] - Chokri Ben Achour ([email protected])
Disclaimer:
===========
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