Microsoft Security Bulletin MS15-106 - Critical

Cumulative Security Update for Internet Explorer (3096441)

Published: October 13, 2015 | Updated: January 27, 2016

Version: 2.1

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 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 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, JScript, VBScript and certain functions handle objects in memory
  • Adding additional permission validations to Internet Explorer

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

For more information about this update, see Microsoft Knowledge Base Article 3096441.

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
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Vista x64 Edition Service Pack 2 Internet Explorer 7
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2008 for 32-bit Systems Service Pack 2 Internet Explorer 7
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows Server 2008 for x64-based Systems Service Pack 2 Internet Explorer 7
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows Server 2008 for Itanium-based Systems Service Pack 2 Internet Explorer 7
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Internet Explorer 8
Windows Vista Service Pack 2 Internet Explorer 8
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Vista x64 Edition Service Pack 2 Internet Explorer 8
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2008 for 32-bit Systems Service Pack 2 Internet Explorer 8
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows Server 2008 for x64-based Systems Service Pack 2 Internet Explorer 8
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows 7 for 32-bit Systems Service Pack 1 Internet Explorer 8
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows 7 for x64-based Systems Service Pack 1 Internet Explorer 8
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Internet Explorer 8
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows Server 2008 R2 for Itanium-based Systems Service Pack 1 Internet Explorer 8
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Internet Explorer 9
Windows Vista Service Pack 2 Internet Explorer 9
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Vista x64 Edition Service Pack 2 Internet Explorer 9
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2008 for 32-bit Systems Service Pack 2 Internet Explorer 9
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows Server 2008 for x64-based Systems Service Pack 2 Internet Explorer 9
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows 7 for 32-bit Systems Service Pack 1 Internet Explorer 9
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows 7 for x64-based Systems Service Pack 1 Internet Explorer 9
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Internet Explorer 9
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Internet Explorer 10
Windows 7 for 32-bit Systems Service Pack 1 Internet Explorer 10
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows 7 for x64-based Systems Service Pack 1 Internet Explorer 10
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Internet Explorer 10
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows 8 for 32-bit Systems Internet Explorer 10
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows 8 for x64-based Systems Internet Explorer 10
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2012 Internet Explorer 10
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows RT Internet Explorer 10[1] (3093983) Remote Code Execution Critical 3087038 in MS15-094
Internet Explorer 11
Windows 7 for 32-bit Systems Service Pack 1 Internet Explorer 11
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows 7 for x64-based Systems Service Pack 1 Internet Explorer 11
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Internet Explorer 11
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows 8.1 for 32-bit Systems Internet Explorer 11
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows 8.1 for x64-based Systems Internet Explorer 11
(3093983)
Remote Code Execution Critical 3087038 in MS15-094
Windows Server 2012 R2 Internet Explorer 11
(3093983)
Remote Code Execution Moderate 3087038 in MS15-094
Windows RT 8.1 Internet Explorer 11[1] (3093983) Remote Code Execution Critical 3087038 in MS15-094
Windows 10 for 32-bit Systems[2] (3105210) Internet Explorer 11 Remote Code Execution Critical 3097617 in MS15-106
Windows 10 for x64-based Systems[2] (3105210) Internet Explorer 11 Remote Code Execution Critical 3097617 in MS15-106

[1]This update is available via Windows Update.

[2]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 3097617 for more information and download links.

*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).

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

Update FAQ

For addressing CVE-2015-2482, CVE-2015-6052, CVE-2015-6055, and CVE-2015-6059, what updates apply to my system?
CVE-2015-2482, CVE-2015-6052, CVE-2015-6055, and CVE-2015-6059 are vulnerabilities in the VBScript engine. Although the attack vector is through Internet Explorer, the vulnerability is addressed by this update (3093983) 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 vulnerability is addressed by the update described in MS15-108.

The update that addresses CVE-2015-2482, CVE-2015-6052, CVE-2015-6055, and CVE-2015-6059 depends on the version of the VBScript and JScript scripting engines that are installed on your system. Consult the following table for update information.

Version MS15-106 MS15-108
VBScript 5.7
(Internet Explorer 7)
Not applicable VBScript 5.7
(3094996)
VBScript 5.8
(Internet Explorer 8)
Internet Explorer 8
(3093983)
VBScript 5.8
(3094995)
(Windows Server core installation on Windows Server 2008 R2 only)
VBScript 5.8
(Internet Explorer 9)
Internet Explorer 9
(3093983)
Not applicable
VBScript 5.8
(Internet Explorer 10)
Internet Explorer 10
(3093983)
Not applicable
VBScript 5.8
(Internet Explorer 11)
Internet Explorer 11
(3093983)
Not applicable

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 October 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-2015-2482 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-2015-6042 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Not applicable Not applicable Windows Clients:
Critical / RCE

Windows Servers:
Moderate / RCE

Not applicable
CVE-2015-6044 Internet Explorer Elevation of Privilege Vulnerability Not applicable Windows Clients:
Important / EoP

Windows Servers:
Low / EoP

Not applicable Not applicable Not applicable Not applicable
CVE-2015-6045 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-2015-6046 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-2015-6047 Internet Explorer Elevation of Privilege Vulnerability Not applicable Windows Clients:
Important / EoP

Windows Servers:
Low / EoP

Windows Clients:
Important / EoP

Windows Servers:
Low / EoP

Windows Clients:
Important / EoP

Windows Servers:
Low / EoP

Windows Clients:
Important / EoP

Windows Servers:
Low / EoP

Windows Clients:
Important / EoP

Windows Servers:
Low / EoP

CVE-2015-6048 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-2015-6049 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

Windows Clients:
Critical / RCE

Windows Servers:
Moderate / RCE

CVE-2015-6050 Internet Explorer Memory Corruption Vulnerability Not applicable Not applicable Not applicable Windows Clients:
Critical / RCE

Windows Servers:
Moderate / RCE

Not applicable Not applicable
CVE-2015-6051 Internet Explorer Elevation of Privilege Not applicable Not applicable Not applicable Windows Clients:
Important / EoP

Windows Servers:
Low / EoP

Windows Clients:
Important / EoP

Windows Servers:
Low / EoP

Not applicable
CVE-2015-6052 VBScript and JScript ASLR Bypass 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

Windows Clients:
Important / SFB

Windows Servers:
Low / SFB

Windows Clients:
Important / SFB

Windows Servers:
Low / SFB

CVE-2015-6053 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-2015-6055 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-2015-6056 Scripting Engine 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-2015-6059 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-2015-6184 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

Windows Clients:
Critical / RCE

Windows Servers:
Moderate / RCE

Vulnerability Information

Multiple Internet Explorer Memory Corruption Vulnerabilities

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 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 Internet Explorer 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 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-2015-6042 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6045 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6046 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6048 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6049 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6050 No No
Internet Explorer Memory Corruption Vulnerability CVE-2015-6184 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 Scripting Engine Memory Corruption Vulnerabilities

Remote code execution vulnerabilities exist in the way that the VBScript and JScript engines, when handling objects in memory in Internet Explorer, render. In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit the vulnerabilities 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 vulnerabilities.

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 vulnerabilities by modifying how the VBScript and JScript scripting engines handle 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
Scripting Engine Memory Corruption Vulnerability CVE-2015-2482 No No
Scripting Engine Memory Corruption Vulnerability CVE-2015-6055 No No
Scripting Engine Memory Corruption Vulnerability CVE-2015-6056 Yes No

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 and JScript.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  
      cacls %windir%\system32\jscript.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  
      cacls %windir%\syswow64\jscript.dll /E /P everyone:N
      

    Impact of Workaround. Websites that use VBScript or JScript 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  
      cacls %windir%\system32\jscript.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    
    cacls %windir%\syswow64\jscript.dll /E /R everyone
    ```

Multiple Internet Explorer Elevation of Privilege Vulnerabilities

Elevation of privilege vulnerabilities exist when Internet Explorer does not properly validate permissions 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 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 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. 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 vulnerabilities could elevate privileges in affected versions of Internet Explorer.

The vulnerabilities by themselves do not allow arbitrary code to be run. However, the vulnerabilities could be used in conjunction with another vulnerability (e.g., 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 the vulnerabilities to cause the arbitrary code to run at a medium integrity level (permissions of the current user).

The update addresses the vulnerabilities by adding permission validations to Internet Explorer.

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 Elevation of Privilege Vulnerability CVE-2015-6044 No No
Internet Explorer Elevation of Privilege Vulnerability CVE-2015-6047 No No
Internet Explorer Elevation of Privilege Vulnerability CVE-2015-6051 No No

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

The following workarounds may be helpful in your situation:

  • Remove the .rdp file association
    Interactive method:

    1. Click Start, click Run, type regedit, and then click OK.
    2. Expand HKEY_CLASSES_ROOT, click RDP.File, and then click the File menu and select Export.
    3. In the Export Registry File dialog box, type RDPfile HKCR file association registry backup.reg and click Save.
      Note This will create a backup of this registry key in the My Documents folder by default.
    4. Press the Delete key on the keyboard to delete the registry key. When prompted to delete the registry value, click Yes.
    5. Expand HKEY_CURRENT_USER, expand Software, expand Microsoft, expand Windows, expand CurrentVersion, expand Explorer, and then expand FileExts.
    6. Click .rdp, and then click the File menu and select Export.
    7. In the Export Registry File dialog box, type rdp HKCU file association registry backup.reg and click Save.
      Note This will create a backup of this registry key in the My Documents folder by default.
    8. Press the Delete key on the keyboard to delete the registry key. When prompted to delete the registry value, click Yes.

    Managed deployment script method:

    1. Make a backup copy of the registry keys from a managed deployment script with the following commands:
    ```
    Regedit.exe /e rdpfile_HKCR_registry_backup.reg HKEY_CLASSES_ROOT\RDP.File  
    Regedit.exe /e rdp_HKCU_registry_backup.reg HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.rdp
    ```

2. Save the following to a file with a .REG extension (that is Delete\_rdp\_file\_association.reg):  


    ```
    Windows Registry Editor Version 5.00  
    [-HKEY_CLASSES_ROOT\RDP.File]  
    [-HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.rdp]
    ```

3. Run the registry script that you created in step 2 on the target machine with the following command:  


    ```
    Regedit.exe /s Delete_rdp_file_association.reg
    ```

**Impact of workaround.** Double-clicking an .rdp file will no longer start mstsc.exe.

**How to undo the workaround:**

Restore the registry key by using Regedit to restore the settings saved in the .REG files.

Internet Explorer Information Disclosure Vulnerability - CVE-2015-6053

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.

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. When this security bulletin was originally issued, Microsoft had not received any information to indicate that the vulnerabilities had been publicly used to attack customers.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

VBScript and JScript ASLR Bypass - CVE-2015-6052

A security feature bypass exists when the VBScript and JScript engines fail to use the Address Space Layout Randomization (ASLR) security feature, allowing an attacker to more reliably predict the memory offsets of specific instructions in a given call stack. The security feature bypass by itself does not allow arbitrary code execution. However, an attacker could use the ASLR bypass in conjunction with another vulnerability, such as a remote code execution vulnerability, that could take advantage of the ASLR bypass to more reliably run arbitrary code on a target system.

In a web-browsing scenario, successful exploitation of an ASLR bypass requires that a user is logged on and running an affected version of Internet Explorer, and browses to a malicious website. Therefore, any systems where a web browser is used frequently, such as workstations or terminal servers, are at the most risk from ASLR bypasses. Servers could be at more risk if administrators allow users to browse and read email on servers. However, best practices strongly discourage allowing this.

The update addresses this ASLR bypass by helping to ensure that affected versions of VBScript properly implement the ASLR security feature. Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued, Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers.

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 Information Disclosure Vulnerability - CVE-2015-6059

An information disclosure vulnerability exists when JScript or 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. When this security bulletin was originally issued, Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers.

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
    ```  

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 (October 13, 2015): Bulletin published.
  • V1.1 (October 14, 2015): Bulletin revised to correct the security impact and severity for CVE-2015-6046. This is an informational change only.
  • V1.2 (October 16, 2015): Bulletin revised to announce a detection change in the 3097617 cumulative update for Windows 10. This is a detection change only. Customers who have already successfully updated their systems do not need to take any action.
  • V2.0 (October 29, 2015) Bulletin revised to announce the release of a new Windows 10 cumulative update (3105210) to address an additional vulnerability, CVE-2015-6045, which has been added to this bulletin. Only customers running Windows 10 systems need to install this new update. Earlier operating systems are either not affected or have received the fix in the original updates of October 13, 2015. See Microsoft Knowledge Base Article 3105210 for more information and the download link.
  • V2.1 (January 27, 2016): Bulletin revised to add CVE-2015-6184. This is an informational change only.

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