Microsoft Windows: Denial of Service -- Remote/Unauthenticated

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2016.0340
 Microsoft Security Bulletin MS16-021: Security Update for Network Policy
    Server RADIUS implementation to Address Denial of Service (3133043)
                             10 February 2016

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

Product:           Microsoft Windows
Publisher:         Microsoft
Operating System:  Windows Server 2008
                   Windows Server 2008 R2
                   Windows Server 2012
                   Windows Server 2012 R2
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2016-0050  

Original Bulletin: 
   link: https://technet.microsoft.com/en-us/library/security/MS16-021

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Microsoft Security Bulletin MS16-021: Security Update for Network Policy 
Server RADIUS implementation to Address Denial of Service (3133043)

Bulletin Number: MS16-021

Bulletin Title: Security Update for NPS RADIUS Server to Address Denial of 
Service

Severity: Important

KB Article: 3133043

Version: 1.0

Published Date: February 9, 2016

Executive Summary

This security update resolves a vulnerability in Microsoft Windows. The 
vulnerability could cause denial of service on a Network Policy Server (NPS) 
if an attacker sends specially crafted username strings to the NPS, which 
could prevent RADIUS authentication on the NPS.

This security update is rated Important for all supported editions of Windows
Server 2008 (excluding Itanium), and Windows Server 2008 R2 (excluding 
Itanium), and all supported editions of Windows Server 2012 and Windows Server
2012 R2.

Affected Software

Windows Server 2008 for 32-bit Systems Service Pack 2

Windows Server 2008 for x64-based Systems Service Pack 2

Windows Server 2008 R2 for x64-based Systems Service Pack 1

Windows Server 2012

Windows Server 2012 R2

Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core 
installation)

Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core 
installation)

Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core 
installation)

Windows Server 2012 (Server Core installation)

Windows Server 2012 R2 (Server Core installation)

Vulnerability Information

Network Policy Server RADIUS Implementation Denial of Service Vulnerability 
CVE-2016-0050

A denial of service vulnerability exists when a Network Policy Server (NPS) 
improperly handles a Remote Authentication Dial-In User Service (RADIUS) 
authentication request. An unauthenticated attacker who successfully exploited
this vulnerability could send specially crafted username strings to a Network
Policy Server (NPS) causing a denial of service condition for RADIUS 
authentication on the NPS.

Note that the denial of service vulnerability would not allow an attacker to 
execute code or to elevate user rights. To exploit the vulnerability, an 
attacker would need to have network access to the affected NPS and then create
an application to send specially crafted RADIUS authentication requests to the
NPS.

The security update addresses the vulnerability by changing how the NPS parses
username queries when implementing RADIUS.

The following table contains links to the standard entry for each 
vulnerability in the Common Vulnerabilities and Exposures list:

Vulnerability title 				CVE number 	Publicly disclosed 	Exploited

Network Policy Server RADIUS Implementation 
Denial of Service Vulnerability 		CVE-2016-0050	No 			No

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