Document Title:
===============
Microsoft Skype v8.34 Android - Authentication Bypass


Date:
=====
2019-01-10


References:
===========
https://www.vulnerability-lab.com/get_content.php?id=2177

MSRC Bulletin: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0622

Video: https://www.vulnerability-lab.com/get_content.php?id=2178


Public Press:
https://www.golem.de/news/sicherheitsluecke-mit-skype-android-pin-umgehen-1901-138551.html
https://www.chip.de/news/Android-User-sollten-App-pruefen-Skype-Sicherheitsluecke-setzt-PIN-Code-ausser-Kraft_157218623.html
https://www.netzwelt.de/news/168997-skype-schwachstelle-erlaubte-umgehen-smartphone-sperre.html
https://www.techbook.de/apps/sicherheitsluecke-wie-ein-skype-anruf-die-smartphone-pin-umgeht

http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-0622

CVE-ID:
=====
CVE-2019-0622


VL-ID:
=====
2177


Common Vulnerability Scoring System:
====================================
6.3


Vulnerability Class:
====================
Authentication Bypass


Introduction:
=============
Skype keeps the world talking. Say “hello” with an instant message, voice or video call – all for free, no matter what 
device they use Skype on. Skype is available on phones, tablets, PCs, and Macs.

(Copy of the Homepage: https://play.google.com/store/apps/details?id=com.skype.raider&hl=en )



Abstract:
=========
The vulnerability laboratory core team researcher discovered a local authentication bypass vulnerability in the official Microsoft Skype android software client.


Report-Timeline:
================
2018-12-10: Researcher Notification & Coordination (Security Researcher)
2018-12-11: Vendor Notification (Microsoft Security Department - MSRC)
2018-12-13: Vendor Response/Feedback (Microsoft Security Department - MSRC)
2018-12-23: Vendor Fix/Patch (Microsoft Service Developer Team)
2018-01-08: Security Acknowledgements (Microsoft Security Department - MSRC)
2018-01-08: Public Disclosure (Vulnerability Laboratory)


Status:
========
Published


Affected Products:
==================

Exploitation-Technique:
=======================
Local


Severity:
=========
High


Details:
========
An elevation of privilege vulnerability exists when Skype for Andriod fails to properly handle specific authentication requests.
An attacker who successfully exploited this vulnerability could bypass Android's lockscreen and access a victim's personal information.
To exploit the vulnerability, an attacker would need have physical access to the phone.The security update addresses the 
vulnerability by correcting how Skype for Android handles authentication requests.


Proof of Concept:
=================
The vulnerability can be exploited by local attackers without user interaction. For security demonstration or to reproduce the 
vulnerability follow the provided information and steps below to continue.


Note: The following video demonstrates the proof of concept used for microsoft (msrc) to reproduce and identify the issue.
The video has been produced and recorded by florain kunushevci a researchers of the public 67vulnerability labs community.


Solution:
=========
2018-12-23: Vendor Fix/Patch (Microsoft Service Developer Team)


Risk:
=====
The security risk of the local authentication bypass vulnerability in the android software client of skype is estimated as high.


Credits:
========
Florian Kunushevci [floriankunushevci@gmail.com] - https://www.vulnerability-lab.com/show.php?user=Florian+Kunushevci


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===========
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