Microsoft Security Bulletin MS15-095 - Critical

Cumulative Security Update for Microsoft Edge (3089665)

Published: September 8, 2015

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 these 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 affected Windows clients. For more information, see the Affected Software section.

The security update addresses the vulnerabilities by modifying how Microsoft Edge handles objects in memory.

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

For more information about this update, see Microsoft Knowledge Base Article 3089665.

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.

Affected Software

Operating System Component Maximum Security Impact Aggregate Severity Rating Updates Replaced
Microsoft Edge
Windows 10 for 32-bit Systems[1] (3081455) Microsoft Edge Remote Code Execution Critical 3081444
Windows 10 for x64-based Systems[1] (3081455) Microsoft Edge Remote Code Execution Critical 3081444

[1]The Windows 10 update is cumulative. In addition to containing non-security updates, it also contains all of the security fixes for all of the Windows 10-affected vulnerabilities shipping with this month’s security release. See Microsoft Knowledge Base Article 3081455 for more information and download links.

Note Windows Server Technical Preview 2 and Windows Server Technical Preview 3 are affected. Customers running this operating system are encouraged to apply the update, which is available via Windows Update.

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 September 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:

Abbreviation Maximum Impact
RCE Remote Code Execution
EoP Elevation of Privilege
ID Information Disclosure
SFB Security Feature Bypass

Vulnerability Severity Ratings and Impact
CVE number Vulnerability Title Microsoft Edge
CVE-2015-2485 Memory Corruption Vulnerability Windows Clients:
Critical / RCE
Windows Servers:
Moderate / RCE
CVE-2015-2486 Memory Corruption Vulnerability Windows Clients:
Critical / RCE
Windows Servers:
Moderate / RCE
CVE-2015-2494 Memory Corruption Vulnerability Windows Clients:
Critical / RCE
Windows Servers:
Moderate / RCE
CVE-2015-2542 Memory Corruption Vulnerability Windows Clients:
Critical / RCE
Windows Servers:
Moderate / RCE

Vulnerability Information

Multiple Memory Corruption Vulnerabilities

Remote code execution vulnerabilities exist when Microsoft Edge improperly accesses objects in memory. These 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 these 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 these vulnerabilities. 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 getting them to click a link in an instant messenger or email message that takes users to the attacker's website, or by getting them to open an attachment sent through email.

An attacker who successfully exploited these 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 these 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. Systems where Microsoft Edge is used frequently, such as workstations or terminal servers, are at the most risk from these vulnerabilities.

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:

Vulnerability title CVE number Publicly disclosed Exploited
Memory Corruption Vulnerability CVE-2015-2485 No No
Memory Corruption Vulnerability CVE-2015-2486 No No
Memory Corruption Vulnerability CVE-2015-2494 No No
Memory Corruption Vulnerability CVE-2015-2542 Yes No

Mitigating Factors

Microsoft has not identified any mitigating factors for these vulnerabilities.

Workarounds

Microsoft has not identified any workarounds for these vulnerabilities.

Security Update Deployment

For Security Update Deployment information see the Microsoft Knowledge Base article referenced here 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 (September 8, 2015): Bulletin published.

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