Microsoft Security Bulletin MS16-155 - Important

• 10/11/2017
• 14 minutes to read
• • 
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Security Update for .NET Framework (3205640)

Published: December 13, 2016 | Updated: February 23, 2017

Version: 2.1

Executive Summary

This security update resolves a vulnerability in Microsoft .NET 4.6.2 Framework’s Data Provider for SQL Server. A security vulnerability exists in Microsoft .NET Framework 4.6.2 that could allow an attacker to access information that is defended by the Always Encrypted feature.

This security update is rated Important for Microsoft .NET Framework 4.6.2. For more information, see the Affected Software and Vulnerability Severity Ratings section.

The security update addresses the vulnerability by correcting the way .NET Framework handles the developer-supplied key, and thus properly defends the data.

For more information, see the Affected Software and Vulnerability Severity Ratings section.

For more information about this update, see Microsoft Knowledge Base Article 3205640.

Affected Software and Vulnerability Severity Ratings

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.

The severity ratings indicated for each affected software 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 December bulletin summary.

Note: Please see the Security Update Guide for a new approach to consuming the security update information. You can customize your views and create affected software spreadsheets, as well as download data via a restful API. For more information, please see the Security Updates Guide FAQ. As a reminder, the Security Updates Guide will be replacing security bulletins as of February 2017. Please see our blog post, Furthering our commitment to security updates, for more details.

Microsoft .NET Framework – Security Only Release^[1]

^[2]This number is the Parent package KB number. Users will be offered the Parent KB; however, the package KB numbers listed for each platform will be displayed in Add Remove Programs.

^[3]Windows 10 updates are cumulative. The monthly security release includes all security fixes for vulnerabilities that affect Windows 10, in addition to non-security updates. The updates are available via the Microsoft Update Catalog. Please note that effective December 13, 2016, Windows 10 and Windows Server 2016 details for the Cumulative Updates will be documented in Release Notes. Please refer to the Release Notes for OS Build numbers, Known Issues, and affected file list information.

Note The vulnerability discussed in this bulletin affects Windows Server 2016 Technical Preview 5. Although an update is available for Windows Server 2016 Technical Preview 5 via Windows Update, Microsoft recommends that customers upgrade to Window Server 2016 at your earliest convenience.

Microsoft .NET Framework – Monthly Rollup Release^[1]

^[2] This number is the Parent package KB number. Users will be offered the Parent KB; however, the package KB numbers listed for each platform will be displayed in Add Remove Programs.

^[3]Windows 10 updates are cumulative. The monthly security release includes all security fixes for vulnerabilities that affect Windows 10, in addition to non-security updates. The updates are available via the Microsoft Update Catalog. Please note that effective December 13, 2016, Windows 10 and Windows Server 2016 details for the Cumulative Updates will be documented in Release Notes. Please refer to the Release Notes for OS Build numbers, Known Issues, and affected file list information.

[4]Microsoft .NET Framework 2.0, 4.5.2 and 4.6/4.6.1 are rollup patches and include all previous updates as well as this month’s updates. Please see This Page for more information.

Note The vulnerability discussed in this bulletin affects Windows Server 2016 Technical Preview 5. An update is available for Windows Server 2016 Technical Preview 5 via Windows Update. To be protected from the vulnerability, Microsoft recommends that customers running Windows Server 2016 Technical Preview 5 upgrade to Windows Server 2016.

Vulnerability Information

.NET Framework Information Disclosure Vulnerabiltiy – CVE-2016-7270

An information disclosure vulnerability exists in Microsoft .NET 4.6.2 Framework’s Data Provider for SQL Server that could allow an attacker to access information that should be defended by the Always Encrypted feature. The vulnerability is caused when .NET Framework improperly uses a developer-supplied key. When this key is misused, it is also possible for access to data to be temporarily lost.

To exploit the vulnerability, an attacker who can access the incorrectly encrypted data could attempt to decrypt the data using an easily guessable key.

The security update addresses the vulnerability by correcting the way .NET Framework handles the developer-supplied key, and thus properly defends the data.

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