Microsoft Security Bulletin MS15-048 - Important

Published: May 12, 2015 | Updated: June 17, 2015

Version: 1.1

This security update resolves vulnerabilities in Microsoft .NET Framework. The most severe of the vulnerabilities could allow elevation of privilege if a user installs a specially crafted partial trust application.

This security update is rated Important for Microsoft .NET Framework 1.1 Service Pack 1, Microsoft .NET Framework 2.0 Service Pack 2, Microsoft .NET Framework 3.5, Microsoft .NET Framework 3.5.1, Microsoft .NET Framework 4, Microsoft .NET Framework 4.5, Microsoft .NET Framework 4.5.1, and Microsoft .NET Framework 4.5.2 on affected releases of Microsoft Windows. For more information, see the Affected Software section.

The security updates address the vulnerabilities by correcting how .NET Framework decrypts XML data and handles objects in memory. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability.

For more information about this update, see Microsoft Knowledge Base Article 3057134.

The following software versions or editions are affected. Versions or editions that are not listed are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.

^[1].NET Framework 4 and .NET Framework 4 Client Profile affected.

^[2]This update is available via Windows Update only.

Systems that run partially trusted .NET Framework applications are at risk from one of the vulnerabilities discussed in this bulletin (Windows Forms Elevation of Privilege Vulnerability - CVE-2015-1673). Where can I go for more information?

To learn more about code access security measures and best practices relating to partially trusted applications, see the following Microsoft Developer Network resources:

• Code Access Security
• Code Access Security Policy Compatibility and Migration
• How to: Run Partially Trusted Code in a Sandbox

How do I determine which version of Microsoft .NET Framework is installed?
You can install and run multiple versions of .NET Framework on a system, and you can install the versions in any order. For more information, see Microsoft Knowledge Base Article 318785.

What is the difference between .NET Framework 4 and .NET Framework 4 Client Profile?
The .NET Framework version 4 redistributable packages are available in two profiles: .NET Framework 4 and .NET Framework 4 Client Profile. The .NET Framework 4 Client Profile is a subset of the .NET Framework 4 profile that is optimized for client applications. It provides functionality for most client applications, including Windows Presentation Foundation (WPF), Windows Forms, Windows Communication Foundation (WCF), and ClickOnce features. This enables faster deployment and a smaller install package for applications that target the .NET Framework 4 Client Profile. For more information, see the MSDN article, .NET Framework Client Profile. 

There are multiple update packages available for some of the affected software. Do I need to install all the updates listed in the Affected Software table for the software?
Yes. Customers should apply all updates offered for the software installed on their systems.

Do I need to install these security updates in a particular sequence?
No. Multiple updates for a given system can be applied in any sequence.

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the May bulletin summary.

^[1].NET Framework 4 and .NET Framework 4 Client Profile affected.

A denial of service vulnerability exists in Microsoft .NET Framework that could allow an unauthenticated attacker to degrade the performance of a .NET-enabled website and disrupt the availability of applications that use Microsoft .NET Framework. The vulnerability exists when Microsoft .NET Framework attempts to decrypt certain specially crafted XML data.

To exploit this vulnerability, an attacker could send specially crafted XML data to a .NET application with the intention of causing processing recursion that leads to the denial-of-service condition. Servers running affected versions of Microsoft .NET Framework are primarily at risk from this vulnerability. The update addresses the vulnerability by correcting how the .NET Framework decrypts XML data.

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.

Microsoft has not identified any mitigating factors for this vulnerability.

Microsoft has not identified any workarounds for this vulnerability.

An elevation of privilege vulnerability exists in Microsoft .NET Framework that is caused when .NET’s Windows Forms (WinForms) libraries improperly handle objects in memory. An attacker who successfully exploited the vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

To exploit this vulnerability, an attacker could use social engineering tactics to lure a user into installing a specially crafted partial trust application. Workstations and servers that run partial-trust .NET Framework applications are primarily at risk from this vulnerability. The update addresses the vulnerability by correcting how .NET Framework handles objects in memory.

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.

Microsoft has not identified any mitigating factors for this vulnerability.

Microsoft has not identified any workarounds for this vulnerability.

For Security Update Deployment information see the Microsoft Knowledge Base article referenced in the Executive Summary.

Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgments for more information.  

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

• V1.0 (May 12, 2015): Bulletin published.
• V1.1 (June 17, 2015): Corrected bulletin replacement for the 3035488 update for .NET Framework 2.0 on all affected editions of Windows Server 2003 Service Pack 2.

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