Summary

• A vulnerability in the Microsoft .NET Framework could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.
  
  The vulnerability exists because the affected software fails to properly validate the source markup of a file. An attacker could exploit the vulnerability by persuading a user to access a file that submits malicious input to the affected software. A successful exploit could allow the attacker to execute arbitrary code and compromise the system completely.
  
  Microsoft confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, the attacker may use misleading language or instructions to persuade a user to access a file that submits malicious input to the affected software.
  
  Microsoft addressed this vulnerability by changing how the affected software validates source markup.

Safeguards

• Administrators are advised to apply the appropriate updates.
  
  Administrators are advised to allow only trusted users to access local systems.
  
  Administrators are advised to allow only privileged users to access administration or management systems.
  
  Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
  
  Administrators are advised to monitor critical systems.

Vendor Announcements

• Microsoft has released detailed information at the following link: Security Update Guide

Fixed Software

• Microsoft customers can obtain updates directly by using the links in the Microsoft Security Update Guide. These updates are also distributed by Windows automatic update features and are available from the Microsoft Update Catalog. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.

Revision History

• Version	Description	Section	Date
  1	Initial public release.	—	Jul-10-2018

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Affected Products

• The security vulnerability applies to the following combinations of products.
  
  

  Primary Products
  Microsoft, Inc.	.NET Framework	4.6 (Base) | 4.6.1 (Base) | 4.6.2 (Base) | 4.7 (Base, .1, .2)

  Associated Products
  Microsoft, Inc.	Windows 7	for 32-bit systems (SP1) | for x64-based systems (SP1)
  	Windows 8.1	for 32-bit Systems (Base) | for x64-based Systems (Base)
  	Windows 10	1607 for 32-bit Systems (Base) | 1607 for x64-based Systems (Base) | 1703 for 32-bit Systems (Base) | 1703 for x64-based Systems (Base) | 1709 for 32-bit Systems (Base) | 1709 for x64-based Systems (Base) | 1803 for 32-bit Systems (Base) | 1803 for x64-based Systems (Base)
  	Windows RT	8.1 (Base)
  	Windows Server 2008 R2	x64-Based Systems Edition (SP1)
  	Windows Server 2012	Original Release (Base)
  	Windows Server 2012 R2	Original Release (Base)
  	Windows Server 2016	x64-Based Systems (Base) | 1709 (Base) | 1803 (Base)