Microsoft Security Bulletin MS15-124 - Critical

Cumulative Security Update for Internet Explorer (3116180)

Published: December 8, 2015 | Updated: December 16, 2015

Version: 1.1

Executive Summary

This security update resolves vulnerabilities in Internet Explorer. The most severe of the vulnerabilities could allow remote code execution if a user views a specially crafted webpage using Internet Explorer. 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 Internet Explorer 7 (IE 7), Internet Explorer 8 (IE 8), Internet Explorer 9 (IE 9), Internet Explorer 10 (IE 10), and Internet Explorer 11 (IE 11) on affected Windows clients, and Moderate for Internet Explorer 7 (IE 7), Internet Explorer 8 (IE 8), Internet Explorer 9 (IE 9), Internet Explorer 10 (IE 10), and Internet Explorer 11 (IE 11) on affected Windows servers. For more information, see the Affected Software section.

The security update addresses the vulnerabilities by:

  • Modifying how Internet Explorer, VBScript, and certain functions handle objects in memory
  • Preventing the XSS filter in Internet Explorer from incorrectly disabling HTML attributes
  • Helping to ensure that Internet Explorer properly enforces content types
  • Helping to ensure that cross-domain policies are properly enforced in Internet Explorer

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

For more information about this update, see Microsoft Knowledge Base Article 3116180.

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*
Internet Explorer 7
Windows Vista Service Pack 2 Internet Explorer 7 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Vista x64 Edition Service Pack 2 Internet Explorer 7 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2008 for 32-bit Systems Service Pack 2 Internet Explorer 7 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows Server 2008 for x64-based Systems Service Pack 2 Internet Explorer 7 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows Server 2008 for Itanium-based Systems Service Pack 2 Internet Explorer 7 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Internet Explorer 8
Windows Vista Service Pack 2 Internet Explorer 8 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Vista x64 Edition Service Pack 2 Internet Explorer 8 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2008 for 32-bit Systems Service Pack 2 Internet Explorer 8 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows Server 2008 for x64-based Systems Service Pack 2 Internet Explorer 8 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows 7 for 32-bit Systems Service Pack 1 Internet Explorer 8 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows 7 for x64-based Systems Service Pack 1 Internet Explorer 8 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Internet Explorer 8 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows Server 2008 R2 for Itanium-based Systems Service Pack 1 Internet Explorer 8 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Internet Explorer 9
Windows Vista Service Pack 2 Internet Explorer 9  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Vista x64 Edition Service Pack 2 Internet Explorer 9  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2008 for 32-bit Systems Service Pack 2 Internet Explorer 9  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows Server 2008 for x64-based Systems Service Pack 2 Internet Explorer 9  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows 7 for 32-bit Systems Service Pack 1 Internet Explorer 9 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows 7 for x64-based Systems Service Pack 1 Internet Explorer 9 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Internet Explorer 9 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Internet Explorer 10
Windows 7 for 32-bit Systems Service Pack 1 Internet Explorer 10 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows 7 for x64-based Systems Service Pack 1 Internet Explorer 10 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Internet Explorer 10 [1]  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows 8 for 32-bit Systems Internet Explorer 10 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows 8 for x64-based Systems Internet Explorer 10 [1]  (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2012 Internet Explorer 10  (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows RT Internet Explorer 10 [1] [2](3104002) Remote Code Execution Critical 3100773 in MS15-112
Internet Explorer 11
Windows 7 for 32-bit Systems Service Pack 1 Internet Explorer 11 (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows 7 for x64-based Systems Service Pack 1 Internet Explorer 11 (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Internet Explorer 11 (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows 8.1 for 32-bit Systems Internet Explorer 11 (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows 8.1 for x64-based Systems Internet Explorer 11 (3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows Server 2012 R2 Internet Explorer 11 (3104002) Remote Code Execution Moderate 3100773 in MS15-112
Windows RT 8.1 Internet Explorer 11 [1] [2](3104002) Remote Code Execution Critical 3100773 in MS15-112
Windows 10 for 32-bit Systems [3](3116869) Internet Explorer 11 Remote Code Execution Critical 3105213 in MS15-112
Windows 10 for x64-based Systems [3]\ (3116869) Internet Explorer 11 Remote Code Execution Critical 3105213 in MS15-112
Windows 10 Version 1511 for 32-bit Systems [3](3116900) Internet Explorer 11 Remote Code Execution Critical 3105211 in MS15-112
Windows 10 Version 1511 for x64-based Systems [3](3116900) Internet Explorer 11 Remote Code Execution Critical 3105211 in MS15-112

[1]For information about changes in support for Internet Explorer beginning January 12, 2016, see Microsoft Support Lifecycle.

[2]This update is available via Windows Update.

[3]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 3 and Windows Server Technical Preview 4 are affected. Customers running these operating systems are encouraged to apply the update, which is available via Windows Update.

*The Updates Replaced column shows only the latest update in any chain of superseded updates. For a comprehensive list of updates replaced, go to the Microsoft Update Catalog, search for the update KB number, and then view update details (updates replaced information is provided on the Package Details tab).

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 December 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 Internet Explorer 7 Internet Explorer 8 Internet Explorer 9 Internet Explorer 10 Internet Explorer 11 Internet Explorer 11 on Windows 10
CVE-2015-6083 Internet Explorer Memory Corruption Vulnerability Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6134 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable Not applicable Not applicable
CVE-2015-6135 Scripting Engine Information Disclosure Vulnerability Not applicable Windows Clients: Important / ID Windows Servers: Low / ID Windows Clients: Important / ID Windows Servers: Low / ID Windows Clients: Important / ID Windows Servers: Low / ID Windows Clients: Important / ID Windows Servers: Low / ID Windows Clients: Important / ID Windows Servers: Low / ID
CVE-2015-6136 Scripting Engine Memory Corruption Vulnerability Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6138 Internet Explorer XSS Filter Bypass Vulnerability Not applicable Windows Clients: Moderate / SFB Windows Servers: Low / SFB Windows Clients: Moderate / SFB Windows Servers: Low / SFB Windows Clients: Moderate / SFB Windows Servers: Low / SFB Windows Clients: Moderate / SFB Windows Servers: Low / SFB Windows Clients: Moderate / SFB Windows Servers: Low / SFB
CVE-2015-6139 Microsoft Browser Elevation of Privilege Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Important / EoP Windows Servers: Low / EoP Windows Clients (Windows 10 Version 1511 not affected): Important / EoP Windows Servers: Low / EoP
CVE-2015-6140 Microsoft Browser Memory Corruption Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6141 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable Not applicable Not applicable
CVE-2015-6142 Microsoft Browser Memory Corruption Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6143 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable
CVE-2015-6144 Microsoft Browser XSS Filter Bypass Vulnerability Not applicable Windows Clients: Moderate / SFB Windows Servers: Low / SFB Windows Clients: Moderate / SFB Windows Servers: Low / SFB Windows Clients: Moderate / SFB Windows Servers: Low / SFB Windows Clients: Moderate / SFB Windows Servers: Low / SFB Windows Clients: Moderate / SFB Windows Servers: Low / SFB
CVE-2015-6145 Internet Explorer Memory Corruption Vulnerability Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable Not applicable Not applicable Not applicable
CVE-2015-6146 Internet Explorer Memory Corruption Vulnerability Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable Not applicable Not applicable Not applicable
CVE-2015-6147 Internet Explorer Memory Corruption Vulnerability Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable Not applicable Not applicable
CVE-2015-6148 Microsoft Browser Memory Corruption Vulnerability Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6149 Internet Explorer Memory Corruption Vulnerability Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable Not applicable Not applicable
CVE-2015-6150 Internet Explorer Memory Corruption Vulnerability Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable
CVE-2015-6151 Microsoft Browser Memory Corruption Vulnerability Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6152 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable Not applicable
CVE-2015-6153 Microsoft Browser Memory Corruption Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6154 Microsoft Browser Memory Corruption Vulnerability Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6155 Microsoft Browser Memory Corruption Vulnerability Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6156 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6157 Internet Explorer Information Disclosure Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Important / ID Windows Servers: Low / ID Windows Clients: Important / ID Windows Servers: Low / ID
CVE-2015-6158 Microsoft Browser Memory Corruption Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6159 Microsoft Browser Memory Corruption Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6160 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Windows Clients: Critical / RCE Windows Servers: Moderate / RCE
CVE-2015-6161 Internet Explorer ASLR Bypass Windows Clients: Important / SFB Windows Servers: Low / SFB Windows Clients: Important / SFB Windows Servers: Low / SFB Windows Clients: Important / SFB Windows Servers: Low / SFB Windows Clients: Important / SFB Windows Servers: Low / SFB Windows Clients: Important / SFB Windows Servers: Low / SFB Windows Clients: Important / SFB Windows Servers: Low / SFB
CVE-2015-6162 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Not applicable Windows Clients: Critical / RCE Windows Servers: Moderate / RCE Not applicable Not applicable
CVE-2015-6164 Internet Explorer XSS Filter Bypass Vulnerability Not applicable Not applicable Windows Clients: Important / SFB Windows Servers: Low / SFB Windows Clients: Important / SFB Windows Servers: Low / SFB Windows Clients: Important / SFB Windows Servers: Low / SFB Not applicable

Update FAQ

Are there any further steps I need to carry out to be protected from the vulnerabilities described in this bulletin?
Yes. It is important to note that your system is not protected from CVE-2015-6161 unless you carry out the instructions included in the vulnerability information section for CVE-2015-6161. This bulletin, MS15-124, provides protections for this issue, but user interaction is required to enable them; the cumulative update does not enable the protections by default.

I am running Internet Explorer 11 on Windows 10. How do I protect my system from CVE-2015-6161?
Your system is affected by this ASLR bypass, but is not protected from it unless you do the following:

  1. Install either Windows 10 Cumulative Update 3116869 or Windows 10 Version 1511 Cumulative Update 3116900. See the Affected Software table for download links.

    Note: these updates are installed automatically on systems that have automatic updating enabled or for users who visit Windows Update and check for updates manually.

  2. Run the Microsoft easy fix available in Microsoft Knowledge Base Article 3125869 to enable the User32 Exception Handler Hardening Feature. An alternative to the easy fix is to enable this feature manually using the steps described in the vulnerability information section for CVE-2015-6161.

I am running a version of Internet Explorer on a version of Windows that was released prior to Windows 10. How do I protect my system from CVE-2015-6161?
Your system is affected by this ASLR bypass, but is not protected from it unless you do the following:

  1. Install Cumulative Update for Internet Explorer 3104002. See the Affected Software table for download links.

  2. Install security update 3109094 in MS15-135.

    Note: these updates are installed automatically on systems that have automatic updating enabled or for users who visit Windows Update and check for updates manually. Also note that you do not need to install the updates in any particular order.

  3. Run the Microsoft easy fix available in Microsoft Knowledge Base Article 3125869 to enable the User32 Exception Handler Hardening Feature. An alternative to the easy fix is to enable this feature manually using the steps described in the vulnerability information section for CVE-2015-6161.

For my particular system and Internet Explorer configuration, which update addresses the vulnerabilities discussed in CVE-2015-6135 and CVE-2015-6136?
CVE-2015-6135 and CVE-2015-6136 are vulnerabilities in the VBScript engine. Although the attack vector is through Internet Explorer, these vulnerabilities are addressed by this update (3104002) only for systems running Internet Explorer 8, Internet Explorer 9, Internet Explorer 10, and Internet Explorer 11. For Internet Explorer 7 and earlier and for systems without Internet Explorer installed, the vulnerabilities are addressed by the update described in MS15-126.

The update that addresses CVE-2015-6135 and CVE-2015-6136 depends on the version of the VBScript scripting engine that is installed on your system. Consult the following table for update information.

Version MS15-124 MS15-126
JScript 5.7 and VBScript 5.7\ (Internet Explorer 7) Not applicable JScript 5.7 and VBScript 5.7\ (3105579)
JScript 5.7 and VBScript 5.8 \ (Internet Explorer 8) Internet Explorer 8 \ (3104002) JScript 5.7 and VBScript 5.8 \ (3105578)\ (Windows Server core installation on Windows Server 2008 R2 only)
JScript 5.7 and VBScript 5.8 \ (Internet Explorer 9) Internet Explorer 9 \ (3104002) Not applicable
JScript 5.7 and VBScript 5.8\ (Internet Explorer 10) Internet Explorer 10 \ (3104002) Not applicable
JScript 5.7 and VBScript 5.8\ (Internet Explorer 11) Internet Explorer 11 \ (3104002) Not applicable
JScript 5.7 and VBScript 5.8\ (Internet Explorer 11 on Windows 10) Internet Explorer 11 \ (3116869) Not applicable
JScript 5.7 and VBScript 5.8 \ (Internet Explorer 11 on Windows 10 Version 1511) Internet Explorer 11 \ (3116900) Not applicable

Vulnerability Information

Multiple Internet Explorer Memory Corruption Vulnerabilities

Multiple remote code execution vulnerabilities exist when Internet Explorer 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 Internet Explorer, 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 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 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 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.

The update addresses the vulnerabilities by modifying how Internet Explorer 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
Internet Explorer Memory Corruption Vulnerability CVE-2015-6083 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6134 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6140 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6141 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6142 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6143 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6145 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6146 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6147 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6148 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6149 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6150 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6151 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6152 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6153 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6154 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6155 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6156 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6158 No No
Microsoft Browser Memory Corruption Vulnerability CVE-2015-6159 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6160 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6162 No No

Mitigating Factors

Microsoft has not identified any mitigating factors for these vulnerabilities.

Workarounds

Microsoft has not identified any workarounds for these vulnerabilities.

FAQ

I am running Internet Explorer on Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, or Windows Server 2012 R2. Does this mitigate these vulnerabilities? 
Yes. By default, Internet Explorer on Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, and Windows Server 2012 R2 runs in a restricted mode that is known as Enhanced Security Configuration. Enhanced Security Configuration is a group of preconfigured settings in Internet Explorer that can reduce the likelihood of a user or administrator downloading and running specially crafted web content on a server. This is a mitigating factor for websites that you have not added to the Internet Explorer Trusted sites zone.

Can EMET help mitigate attacks that attempt to exploit these vulnerabilities? 
Yes. The Enhanced Mitigation Experience Toolkit (EMET) enables users to manage security mitigation technologies that help make it more difficult for attackers to exploit memory corruption vulnerabilities in a given piece of software. EMET can help mitigate attacks that attempt to exploit these vulnerabilities in Internet Explorer on systems where EMET is installed and configured to work with Internet Explorer.

For more information about EMET, see the Enhanced Mitigation Experience Toolkit.

Multiple Microsoft Browser XSS Filter Bypass Vulnerabilities

Multiple XSS filter bypass vulnerabilities exist in the way that Internet Explorer disables an HTML attribute in otherwise appropriately filtered HTTP response data. The vulnerabilities could allow initially disabled scripts to run in the wrong security context, leading to information disclosure.

An attacker could post on a website specially crafted content that is designed to exploit the vulnerabilities. The attacker would then have to convince the user to view the content on the affected website. If the user then browses to the website, the XSS filter disables HTML attributes in the specially crafted content, creating a condition that could allow malicious script to run in the wrong security context, leading to information disclosure.

An attacker who successfully exploited the vulnerabilities could cause script to run on another user's system in the guise of a third-party website. Such script would run inside the browser when visiting the third-party website, and could take any action on the user's system that the third-party website was permitted to take. The vulnerabilities could only be exploited if the user clicked a hypertext link, either in an HTML email or if the user visited an attacker's website or a website containing content that is under the attacker’s control.

The update addresses the vulnerabilities by preventing the XSS filter in Internet Explorer from incorrectly disabling HTML attributes.

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
Internet Explorer XSS Filter Bypass Vulnerability CVE-2015-6138 No No
Microsoft Browser XSS Filter Bypass Vulnerability CVE-2015-6144 No No

Mitigating Factors

Microsoft has not identified any mitigating factors for these vulnerabilities.

Workarounds

Microsoft has not identified any workarounds for these vulnerabilities.

Scripting Engine Information Disclosure Vulnerability - CVE-2015-6135

An information disclosure vulnerability exists when VBScript improperly discloses the contents of its memory, which could provide an attacker with information to further compromise the user’s computer or data.

To exploit the vulnerability, an attacker must know the memory address of where the object was created. The update addresses the vulnerability by changing the way certain functions handle objects in memory.

Microsoft received information about this vulnerability through coordinated vulnerability disclosure. At the time this security bulletin was originally issued, Microsoft was unaware of any attack attempting to exploit this vulnerability.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

The following workarounds may be helpful in your situation:

  • Restrict access to VBScript.dll

    • For 32-bit systems, enter the following command at an administrative command prompt:
            takeown /f %windir%\system32\vbscript.dll   
            cacls %windir%\system32\vbscript.dll /E /P everyone:N
    
    • For 64-bit systems, enter the following command at an administrative command prompt:
            takeown /f %windir%\syswow64\vbscript.dll   
            cacls %windir%\syswow64\vbscript.dll /E /P everyone:N
    

    Impact of Workaround. Websites that use VBScript may not work properly.

    How to undo the workaround:

    • For 32-bit systems, enter the following command at an administrative command prompt:
              cacls %windir%\system32\vbscript.dll /E /R everyone
    
    • For 64-bit systems, enter the following command at an administrative command prompt:
            cacls %windir%\syswow64\vbscript.dll /E /R everyone
    

Scripting Engine Memory Corruption Vulnerability - CVE-2015-6136

A remote code execution vulnerability exists in the way that the VBScript engine renders when handling objects in memory in Internet Explorer. The vulnerability could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user.

In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit the vulnerability through Internet Explorer and then convince a user to view the website. An attacker could also embed an ActiveX control marked "safe for initialization" in an application or Microsoft Office document that hosts the IE rendering engine. The attacker could also take advantage of compromised websites, and websites that accept or host user-provided content or advertisements. These websites could contain specially crafted content that could exploit the vulnerability.

An attacker who successfully exploited the vulnerability 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 vulnerability 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 the VBScript scripting engine handles objects in memory.

Microsoft received information about this vulnerability through coordinated vulnerability disclosure. At the time this security bulletin was originally issued, Microsoft was unaware of any attack attempting to exploit this vulnerability.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

The following workarounds may be helpful in your situation:

  • Restrict access to VBScript.dll

    • For 32-bit systems, enter the following command at an administrative command prompt:
    takeown /f %windir%\system32\vbscript.dll   
    cacls %windir%\system32\vbscript.dll /E /P everyone:N
    
    • For 64-bit systems, enter the following command at an administrative command prompt:
    takeown /f %windir%\syswow64\vbscript.dll   
    cacls %windir%\syswow64\vbscript.dll /E /P everyone:N
    

    Impact of Workaround. Websites that use VBScript may not work properly.

    How to undo the workaround:

    • For 32-bit systems, enter the following command at an administrative command prompt:
    cacls %windir%\system32\vbscript.dll /E /R everyone
    
    • For 64-bit systems, enter the following command at an administrative command prompt:
    cacls %windir%\syswow64\vbscript.dll /E /R everyone
    

Microsoft Browser Elevation of Privilege Vulnerability - CVE-2015-6139

An elevation of privilege vulnerability exists when Internet Explorer does not properly enforce content types. An attacker who successfully exploited the vulnerability could run arbitrary script with elevated privileges.

In a web-based attack scenario, an attacker could host a website that is used to 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 this 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. For example, an attacker could trick users into clicking a link that takes them to the attacker's site. An attacker who successfully exploited this vulnerability could elevate privileges in affected versions of Internet Explorer.

The update addresses the vulnerability by helping to ensure that Internet Explorer properly enforces content types. Microsoft received information about this vulnerability through coordinated vulnerability disclosure. At the time this security bulletin was originally issued, Microsoft was unaware of any attack attempting to exploit this vulnerability.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

Internet Explorer Information Disclosure Vulnerability - CVE-2015-6157

An information disclosure vulnerability exists when Internet Explorer improperly discloses the contents of its memory. An attacker who successfully exploited this vulnerability could provide the attacker with information to further compromise the user’s system.

In a web-based attack scenario, an attacker could host a website in an attempt to exploit this vulnerability. Additionally, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit this 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. For example, an attacker could trick users into clicking a link that takes them to the attacker's site.

The update addresses the vulnerability by changing the way certain functions handle objects in memory. Microsoft received information about the vulnerability through coordinated vulnerability disclosure. At the time this security bulletin was originally issued, Microsoft was unaware of any attack attempting to exploit this vulnerability.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

Internet Explorer ASLR Bypass - CVE-2015-6161

A security feature bypass for Internet Explorer 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 does not allow arbitrary code execution. However, an attacker could use this ASLR bypass 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 requires a user to be logged on and running an affected version of Internet Explorer. The user would then need to browse to a malicious site.

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
Internet Explorer ASLR Bypass CVE-2015-6161 No No

Important: Your system is not protected from this ASLR Bypass unless you install the applicable updates and then enable the User32 Exception Handler Hardening Feature:

Enabling the User32 Exception Handler Hardening Feature

A Microsoft easy fix is available if you do not wish to manually enable the User32 Exception Handler Hardening Feature in Registry Editor. See Microsoft Knowledge Base Article 3125869 for the easy fix.

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

For 32-bit operating systems:

  1. Click Start, click Run, type Regedit in the Open box, and then click OK.

  2. Navigate to the following registry location:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\FeatureControl\
    
  3. Create a new key with the name FEATURE_ALLOW_USER32_EXCEPTION_HANDLER_HARDENING

  4. Under the new key, add a new DWORD entry “iexplore.exe”.

  5. Set the DWORD value to 1.

For x64-based operating systems:

  1. Click Start, click Run, type Regedit in the Open box, and then click OK.

  2. Navigate to the following registry location:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\FeatureControl\
    
  3. Create a new key with the name FEATURE_ALLOW_USER32_EXCEPTION_HANDLER_HARDENING

  4. Under the new key, add a new DWORD entry “iexplore.exe”.

  5. Set the DWORD value to 1.

  6. Navigate to the following registry location:

    HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\Main\FeatureControl\
    
  7. Create a new key with the name FEATURE_ALLOW_USER32_EXCEPTION_HANDLER_HARDENING

  8. Under the new key, add a new DWORD entry “iexplore.exe”.

  9. Set the DWORD value to 1.

See Microsoft Security Bulletin MS15-135 for the download links for update 3109094.

See Knowledge Base Article 3125869 for more information and the Microsoft easy fix.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

Internet Explorer XSS Filter Bypass Vulnerability - CVE-2015-6164

A security feature bypass vulnerability exists when Internet Explorer does not properly enforce cross-domain policies. The vulnerability 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 that is used to 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 this 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. For example, an attacker could trick users into clicking a link that takes them to the attacker's site. An attacker who successfully exploited this vulnerability could elevate privileges in affected versions of Internet Explorer.

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 could take advantage of the elevated privileges when running arbitrary code. For example, an attacker could exploit another vulnerability to run arbitrary code through Internet Explorer, but due to 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 helping to ensure that cross-domain policies are properly enforced in Internet Explorer. This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2015-6164. At the time this security bulletin was originally issued, Microsoft was unaware of any attack attempting to exploit this vulnerability.

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 (December 8, 2015): Bulletin published.
  • V1.1 (December 16, 2015): Bulletin revised to further clarify the steps users must take to be protected from the vulnerability described in CVE-2015-6161. This bulletin, MS15-124, provides protections for this issue, but user action is required to enable them; the cumulative update for Internet Explorer does not enable the protections by default. Before applying the protections, Microsoft recommends that customers perform testing appropriate to their environment and system configurations.

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