Microsoft Skype for Business and Microsoft Lync: Reduced Security -- Remote with User Interaction

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2015.2804
  Microsoft Security Bulletin MS15-123: Important -- Security Update for
  Skype for Business and Lync to Address Information Disclosure (3105872)
                             11 November 2015

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Microsoft Skype for Business
                   Microsoft Lync
Publisher:         Microsoft
Operating System:  Windows
Impact/Access:     Reduced Security -- Remote with User Interaction
Resolution:        Patch/Upgrade
CVE Names:         CVE-2015-6061  

Original Bulletin: 
   https://technet.microsoft.com/en-us/library/security/MS15-123

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Microsoft Security Bulletin MS15-123: Important -- Security Update for Skype 
for Business and Lync to Address Information Disclosure (3105872)

Document Metadata

Bulletin Number: MS15-123

Bulletin Title: Security Update for Skype for Business and Lync to Address 
Information Disclosure

Severity: Important

KB Article: 3105872

Version: 1.0

Published Date: November 10, 2015

Executive Summary

This security update resolves a vulnerability in Microsoft Lync. The 
vulnerability could allow information disclosure if an attacker invites a 
target user to an instant message session and then sends that user a message 
containing specially crafted JavaScript content.

This security update is rated Critical for all supported editions of Skype 
2016, Microsoft Lync 2013, and Microsoft Lync 2010; it is also rated Important
for certain Microsoft Lync Room System components. For more information, see 
the Affected Software section.

Affected Software

Skype for Business 2016 (32-bit)

Skype for Business Basic 2016 (32-bit)

Skype for Business 2016 (64-bit)

Skype for Business Basic 2016 (64-bit)

Microsoft Lync 2013 Service Pack 1 (32-bit) (Skype for Business)[1]

Microsoft Lync Basic 2013 Service Pack 1 (32-bit) (Skype for Business 
Basic)[1]

Microsoft Lync 2013 Service Pack 1 (64-bit) (Skype for Business)[1]

Microsoft Lync Basic 2013 Service Pack 1 (64-bit)[1] (Skype for Business 
Basic)

Microsoft Lync 2010 (32-bit)

Microsoft Lync 2010 (64-bit)

Microsoft Lync 2010 Attendee[2] (user level install)

Microsoft Lync 2010 Attendee (admin level install)

Microsoft Lync Room System (For SMART Room System)

Microsoft Lync Room System (For Crestron RL)

[1]Before installing this update, you must have update 2965218 and security 
update 3039779 installed. See the Update FAQ for more information.

[2]This update is available from the Microsoft Download Center only.

Vulnerability Information

Server Input Validation Security Feature Bypass Vulnerability - CVE-2015-6061

A security feature bypass vulnerability exists when Skype for Business and 
Lync Servers improperly sanitize specially crafted content. An attacker who 
successfully exploited the vulnerability could execute HTML and JavaScript 
content in the Skype for Business or Lync context. The attacker could use this
vulnerability to open a webpage using the default browser, open another 
messaging session with a third party, or potentially trigger URIs that are 
defined by other applications on the client's system.

To exploit the vulnerability an attacker could invite a target user to an 
instant message session and then send that user a message containing specially
crafted JavaScript content. The update addresses the vulnerability by 
correcting how Skype for Business and Lync Servers sanitize content.

Microsoft received information about this vulnerability through coordinated 
vulnerability disclosure. When this security bulletin was issued, Microsoft 
had not received any information to indicate that this vulnerability had been
publicly used to attack customers.

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