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 those who operate 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 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. In addition to containing non-security updates, they also contain all of the security fixes for all of the Windows 10-affected vulnerabilities shipping with the monthly security release. The updates are available via the Microsoft Update Catalog.

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

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 February 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:

Microsoft Browser Spoofing Vulnerability – CVE-2016-0077

A spoofing vulnerability exists when a Microsoft browser does not properly parse HTTP responses. An attacker who successfully exploited this vulnerability could trick a user by redirecting them to a specially crafted website. The specially crafted website could spoof content or be used as a pivot to chain an attack with other vulnerabilities in web services.

To exploit the vulnerability, the user must click a specially crafted URL. In an email attack scenario, an attacker could send an email message containing the specially crafted URL to the user in an attempt to convince the user to click it.

In a web-based attack scenario, an attacker could host a specially crafted website designed to appear as a legitimate website to the user. However, the attacker would have no way to force the user to visit the specially crafted website. The attacker would have to convince the user to visit the specially crafted website, typically by way of enticement in an email or Instant Messenger message, and then convince the user to interact with content on the website. The update addresses the vulnerability by correcting how Microsoft Edge parses HTTP responses.

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

Mitigating Factors

Workarounds

Microsoft Edge ASLR Bypass Vulnerability – CVE-2016-0080

A security feature bypass vulnerability for Microsoft Edge exists as a result of how exceptions are handled when dispatching certain window messages, allowing an attacker to probe the layout of the address space and thereby bypassing Address Space Layout Randomization (ASLR). By itself, the ASLR bypass vulnerability does not allow arbitrary code execution. However, an attacker could use the ASLR bypass vulnerability in conjunction with another vulnerability, such as a remote code execution vulnerability, to run arbitrary code on a target system.

Successful exploitation of the ASLR bypass vulnerability requires a user to be logged on and running an affected version of Microsoft Edge. The user would then need to browse to a malicious site. The update addresses the ASLR bypass vulnerability by helping to ensure that Microsoft Edge properly handles exceptions when dispatching certain window messages.

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

Mitigating Factors

Workarounds

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 in such a way that an attacker could 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 who successfully exploited the vulnerabilities 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 vulnerability 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:

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.