Microsoft Security Bulletin MS16-038 - Critical

Cumulative Security Update for Microsoft Edge (3148532)

Published: April 12, 2016

Version: 1.0

Executive Summary

This security update resolves vulnerabilities in Microsoft Edge. The most severe of the vulnerabilities could allow remote code execution if a user views a specially crafted webpage using Microsoft Edge. An attacker who successfully exploited the vulnerabilities could gain the same user rights as the current user. Customers whose accounts are configured to have fewer user rights on the system could be less impacted than users with administrative user rights.

This security update is rated Critical for Microsoft Edge on Windows 10. For more information, see the Affected Software section.

The update addresses the vulnerabilities by:

• Modifying how Microsoft Edge handles objects in memory.
• Ensuring that cross-domain policies are properly enforced in Microsoft Edge.

For more information about the vulnerability, see the Vulnerability Information section.

For more information about this update, see Microsoft Knowledge Base Article 3148532.

Affected Software

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]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.

Note Windows Server 2016 Technical Preview 4 and Windows Server 2016 Technical Preview 5 are affected. Customers running these operating systems are encouraged to apply the update, which is available via Windows Update.

Update FAQ

Does this update contain any additional security-related changes to functionality?
In addition to the changes that are listed for the vulnerabilities described in this bulletin, this update includes defense-in-depth updates to help improve security-related features.

Severity Ratings and Vulnerability Identifiers

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 April bulletin summary.

Where specified in the Severity Ratings and Impact table, Critical, Important, and Moderate values indicate severity ratings. For more information, see Security Bulletin Severity Rating System. Refer to the following key for the abbreviations used in the table to indicate maximum impact:

Vulnerability Information

Multiple Microsoft Edge Memory Corruption Vulnerabilities

Multiple remote code execution vulnerabilities exist when Microsoft Edge improperly accesses objects in memory. The vulnerabilities could corrupt memory that enables an attacker to execute arbitrary code in the context of the current user.

An attacker could host a specially crafted website that is designed to exploit the vulnerabilities through Microsoft Edge, and then convince a user to view the website. The attacker could also take advantage of compromised websites and websites that accept or host user-provided content or advertisements by adding specially crafted content that could exploit the vulnerability. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by way of enticement in an email or Instant Messenger message, or by getting them to open an attachment sent through email.

An attacker who successfully exploited the vulnerabilities could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. The update addresses the vulnerabilities by modifying how Microsoft Edge handles objects in memory.

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

Mitigating Factors

Microsoft has not identified any mitigating factors for these vulnerabilities.

Workarounds

Microsoft has not identified any workarounds for these vulnerabilities.

Microsoft Edge Elevation of Privilege - CVE-2016-0158

An elevation of privilege vulnerability exists when Microsoft Edge does not properly enforce cross-domain policies, which could allow an attacker to access information from one domain and inject it into another domain. In a web-based attack scenario, an attacker could host a website in an attempt to exploit the vulnerability.

In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit the vulnerability. However, in all cases an attacker could not force a user to view the attacker-controlled content. Instead, an attacker would have to convince a user to take action. For example, an attacker could trick a user into clicking a link that takes the user to the attacker's site. An attacker who successfully exploited this vulnerability could elevate privileges in affected versions of Microsoft Edge.

The vulnerability by itself does not allow arbitrary code to be run. However, the vulnerability could be used in conjunction with another vulnerability (for example, a remote code execution vulnerability) that an attacker could use to take advantage of the elevated privileges when running arbitrary code. For example, an attacker could exploit another vulnerability to run arbitrary code through Microsoft Edge, but because of the context in which processes are launched by Microsoft Edge, the code might be restricted to run at a low integrity level (very limited permissions). However, an attacker could, in turn, exploit this vulnerability to cause the arbitrary code to run at a medium integrity level (the permissions of the current user). The update addresses the vulnerability by helping to ensure that cross-domain policies are properly enforced in Microsoft Edge.

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

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

Microsoft Edge Elevation of Privilege Vulnerability - CVE-2016-0161

An elevation of privilege vulnerability exists when Microsoft Edge does not properly validate JavaScript under specific conditions, potentially allowing a script to be run with elevated privileges. In a web-based attack scenario, an attacker could host a website in an attempt to exploit this vulnerability.

In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit the vulnerability. However, in all cases an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action. For example, an attacker could trick users into clicking a link that takes them to the attacker's site. An attacker who successfully exploited the vulnerability could elevate privileges in affected versions of Microsoft Edge. An attacker could then leverage these privileges with another vulnerability to run arbitrary code with medium integrity level privileges (permissions of the current user).

This vulnerability by itself does not allow arbitrary code to be run. However, this vulnerability could be used in conjunction with another vulnerability (for example, a remote code execution vulnerability) that could take advantage of the elevated privileges when running arbitrary code. For example, an attacker could exploit another vulnerability to run arbitrary code through Microsoft Edge, but because of the context in which processes are launched by Internet Explorer, the code might be restricted to run at a low integrity level (very limited permissions).

However, an attacker could, in turn, exploit this vulnerability to cause the arbitrary code to run at a medium integrity level (permissions of the current user). The update addresses the vulnerability by adding additional permission validations to Microsoft Edge.

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

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

Security Update Deployment

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

Acknowledgments

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

Disclaimer

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.

Revisions

• V1.0 (April 12, 2016): Bulletin published.

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