Published: 03/23/2020 | Last Updated : 04/14/2020

Microsoft has become aware of limited targeted Windows 7 based attacks that could leverage un-patched vulnerabilities in the Adobe Type Manager Library, and is providing the following guidance to help reduce customer risk until the security update is released. We appreciate the efforts of our industry partners and are complying with a 7-day timeline for disclosing information regarding these limited attacks.

Two remote code execution vulnerabilities exist in Microsoft Windows when the Windows Adobe Type Manager Library improperly handles a specially-crafted multi-master font - Adobe Type 1 PostScript format.

There are multiple ways an attacker could exploit the vulnerability, such as convincing a user to open a specially crafted document or viewing it in the Windows Preview pane.

Microsoft is aware of this vulnerability and working on a fix. Updates that address security vulnerabilities in Microsoft software are typically released on Update Tuesday, the second Tuesday of each month. This predictable schedule allows for partner quality assurance and IT planning, which helps maintain the Windows ecosystem as a reliable, secure choice for our customers. The operating system versions that are affected by this vulnerability are listed below. Please see the mitigation and workarounds for guidance on how to reduce the risk.

Please Note: The threat is low for those systems running Windows 10 due to mitigations that were put in place with the first version released in 2015. Please see the mitigation section for details. Microsoft is not aware of any attacks against the Windows 10 platform. The possibility of remote code execution is negligible and elevation of privilege is not possible. We do not recommend that IT administrators running Windows 10 implement the workarounds described below.

Microsoft recommends upgrading to the Windows 10 family of clients and servers.

Security Updates

To determine the support life cycle for your software version or edition, see the Microsoft Support Lifecycle.

Product	Platform	Article	Download	Impact	Severity	Supersedence
Windows 10 for 32-bit Systems				Remote Code Execution	Important
Windows 10 for x64-based Systems				Remote Code Execution	Important
Windows 10 Version 1607 for 32-bit Systems				Remote Code Execution	Important
Windows 10 Version 1607 for x64-based Systems				Remote Code Execution	Important
Windows 10 Version 1709 for 32-bit Systems				Remote Code Execution	Important
Windows 10 Version 1709 for ARM64-based Systems				Remote Code Execution	Important
Windows 10 Version 1709 for x64-based Systems				Remote Code Execution	Important
Windows 10 Version 1803 for 32-bit Systems				Remote Code Execution	Important
Windows 10 Version 1803 for ARM64-based Systems				Remote Code Execution	Important
Windows 10 Version 1803 for x64-based Systems				Remote Code Execution	Important
Windows 10 Version 1809 for 32-bit Systems				Remote Code Execution	Important
Windows 10 Version 1809 for ARM64-based Systems				Remote Code Execution	Important
Windows 10 Version 1809 for x64-based Systems				Remote Code Execution	Important
Windows 10 Version 1903 for 32-bit Systems				Remote Code Execution	Important
Windows 10 Version 1903 for ARM64-based Systems				Remote Code Execution	Important
Windows 10 Version 1903 for x64-based Systems				Remote Code Execution	Important
Windows 10 Version 1909 for 32-bit Systems				Remote Code Execution	Important
Windows 10 Version 1909 for ARM64-based Systems				Remote Code Execution	Important
Windows 10 Version 1909 for x64-based Systems				Remote Code Execution	Critical
Windows 7 for 32-bit Systems Service Pack 1				Remote Code Execution	Critical
Windows 7 for x64-based Systems Service Pack 1				Remote Code Execution	Critical
Windows 8.1 for 32-bit systems				Remote Code Execution	Critical
Windows 8.1 for x64-based systems				Remote Code Execution	Critical
Windows RT 8.1				Remote Code Execution	Critical
Windows Server 2008 for 32-bit Systems Service Pack 2				Remote Code Execution	Critical
Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)				Remote Code Execution	Critical
Windows Server 2008 for Itanium-Based Systems Service Pack 2				Remote Code Execution	Critical
Windows Server 2008 for x64-based Systems Service Pack 2				Remote Code Execution	Critical
Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)				Remote Code Execution	Critical
Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1				Remote Code Execution	Critical
Windows Server 2008 R2 for x64-based Systems Service Pack 1				Remote Code Execution	Critical
Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)				Remote Code Execution	Critical
Windows Server 2012				Remote Code Execution	Critical
Windows Server 2012 (Server Core installation)				Remote Code Execution	Critical
Windows Server 2012 R2				Remote Code Execution	Critical
Windows Server 2012 R2 (Server Core installation)				Remote Code Execution	Critical
Windows Server 2016				Remote Code Execution	Important
Windows Server 2016 (Server Core installation)				Remote Code Execution	Important
Windows Server 2019				Remote Code Execution	Important
Windows Server 2019 (Server Core installation)				Remote Code Execution	Important

Mitigations

For systems running supported versions of Windows 10 a successful attack could only result in code execution within an AppContainer sandbox context with limited privileges and capabilities.

Version	Fonts Process With	ATMFD.DLL status
Windows 10	fontdrvhost.exe in user mode appcontainer. Installed fonts are still processed in kernel mode	Present
Windows 10 Version 1607/Server 2016	fontdrvhost.exe in user mode appcontainer. Installed fonts are still processed in kernel mode	Present
Windows 10 1703	All fonts are processed in fontdrvhost.exe in user mode appcontainer.	Present but not used
Windows 10 1709	All fonts are processed in fontdrvhost.exe in user mode appcontainer.	Not present
Windows 10 1803/Windows Server, version 1803	All fonts are processed in fontdrvhost.exe in user mode appcontainer.	Not present
Windows 10 1809/Server 2019	All fonts are processed in fontdrvhost.exe in user mode appcontainer.	Not present
Windows 10 1903/Windows Server, version 1903	All fonts are processed in fontdrvhost.exe in user mode appcontainer.	Not present
Windows 10 1909/Windows Server, version 1909	All fonts are processed in fontdrvhost.exe in user mode appcontainer.	Not present

For more information, see Mitigating font exploits with AppContainer.

Workarounds

There are several different workarounds in this section. Not all may apply to all networks.

Workaround	Applicability
Disable the Preview Pane and Details Pane in Windows Explorer	Works on all systems but won't mitigate the issue if you open a document with the vulnerable font class
Disable the WebClient service	Works on all systems but won't mitigate the issue if you open a document with the vulnerable font class
DisableATMFD registry key using a managed deployment script	Only works on older (before Windows 10) but completely mitigates the issue though can introduce usability issues in rare cases
DisableATMFD registry key manually	Only works on older (before Windows 10) but completely mitigates the issue though can introduce usability issues in rare cases
Rename ATMFD.DLL	Only works on older (before Windows 10) but completely mitigates the issue though can introduce usability issues in rare cases

Note: We do not recommend that IT administrators running Windows 10 implement the workarounds described below. ATMFD.DLL is not present in Windows 10 installations starting with Windows 10, version 1709. Newer versions do not have this DLL. See the Mitigation section for more information.

Disable the Preview Pane and Details Pane in Windows Explorer

Disabling the Preview and Details panes in Windows Explorer prevents the automatic display of OTF fonts in Windows Explorer. While this prevents malicious files from being viewed in Windows Explorer, it does not prevent a local, authenticated user from running a specially crafted program to exploit this vulnerability.

To disable these panes in Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, and Windows 8.1, perform the following steps:

1. Open Windows Explorer, click Organize, and then click Layout.
2. Clear both the Details pane and Preview pane menu options.
3. Click Organize, and then click Folder and search options.
4. Click the View tab.
5. Under Advanced settings, check the Always show icons, never thumbnails box.
6. Close all open instances of Windows Explorer for the change to take effect.

To disable these panes in all supported client and server versions of Windows 10, perform the following steps:

1. Open Windows Explorer, click the View tab.
2. Clear both the Details pane and Preview pane menu options.
3. Click Options, and then click Change folder and search options.
4. Click the View tab.
5. Under Advanced settings, check the Always show icons, never thumbnails box.
6. Close all open instances of Windows Explorer for the change to take effect.

Impact of workaround.

Windows Explorer will not automatically display OTF fonts.

How to undo the workaround.

To re-enable the Preview and Details panes in Windows Explorer for Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, and Windows 8.1:

1. Open Windows Explorer, click Organize, and then click Layout.
2. Select both the Details pane and Preview pane menu options.
3. Click Organize, and then click Folder and search options.
4. Click the View tab.
5. Under Advanced settings, clear the Always show icons, never thumbnails box.
6. Close all open instances of Windows Explorer for the change to take effect.

To re-enable the Preview and Details panes in Windows Explorer for all supported client and server versions of Windows 10, perform the following steps:

1. Open Windows Explorer, click the View tab.
2. Select both the Details pane and Preview pane menu options.
3. Click Options, and then click Change folder and search options.
4. Click the View tab.
5. Under Advanced settings, clear the Always show icons, never thumbnails box.
6. Close all open instances of Windows Explorer for the change to take effect.

Disable the WebClient service

Disabling the WebClient service helps protect affected systems from attempts to exploit this vulnerability by blocking the most likely remote attack vector through the Web Distributed Authoring and Versioning (WebDAV) client service. After applying this workaround it is still possible for remote attackers who successfully exploit this vulnerability to cause the system to run programs located on the targeted user's computer or the Local Area Network (LAN), but users will be prompted for confirmation before opening arbitrary programs from the Internet.

To disable the WebClient Service, perform the following steps:

1. Click Start, click Run (or press the Windows Key and R on the keyboard), type Services.msc and then click OK.
2. Right-click WebClient service and select Properties.
3. Change the Startup type to Disabled. If the service is running, click Stop.
4. Click OK and exit the management application.

Impact of workaround.

When the WebClient service is disabled, Web Distributed Authoring and Versioning (WebDAV) requests are not transmitted. In addition, any services that explicitly depend on the WebClient service will not start, and an error message will be logged in the System log. For example, WebDAV shares will be inaccessible from the client computer.

How to undo the workaround.

To re-enable the WebClient Service, perform the following steps:

1. Click Start, click Run (or press the Windows Key and R on the keyboard), type Services.msc and then click OK.
2. Right-click WebClient service and select Properties.
3. Change the Startup type to Automatic. If the service is not running, click Start.
4. Click OK and exit the management application.

DisableATMFD registry key using a managed deployment script

Please Note: This workaround works for Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, and Windows 8.1. ATMFD.DLL is not present in Windows 10 installations starting with Windows 10, version 1709.

Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

1. Create a text file named ATMFD-disable.reg that contains the following text:
   
   ATMFD-disable.reg
   
   Download
   
   
   Code:

   Windows Registry Editor Version 5.00
       [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows]
       "DisableATMFD"=dword:00000001

2. Run regedit.exe.
3. In Registry Editor, click the File menu and then click Import.
4. Navigate to and select the ATMFD-disable.reg file that you created in the first step. (Note If your file is not listed where you expect it to be, ensure that it has not been automatically given a .txt file extension, or change the dialog’s file extension parameters to All Files).
5. Click Open and then click OK to close Registry Editor.

Impact of workaround

Applications that rely on embedded font technology will not display properly. Disabling ATMFD.DLL could cause certain applications to stop working properly if they use OpenType fonts. Microsoft Windows does not release any OpenType fonts natively. However, third-party applications could install them and they could be affected by this change.

How to undo the workaround

1. Create a text file named ATMFD-enable.reg that contains the following text:
   
   ATMFD-enable.reg
   
   Download
   
   
   Code:

       Windows Registry Editor Version 5.00
       [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows]
       "DisableATMFD"=dword:00000000

2. Run regedit.exe.
3. In Registry Editor, click the File menu and then click Import.
4. Navigate to and select the ATMFD-enable.reg file that you created in the first step. (Note If your file is not listed where you expect it to be, ensure that it has not been automatically given a .txt file extension, or change the dialog’s file extension parameters to All Files).
5. Click Open and then click OK to close Registry Editor.

DisableATMFD registry key manually

Please Note: This workaround works for Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, and Windows 8.1. ATMFD.DLL is not present in Windows 10 installations starting with Windows 10, version 1709. Newer versions do not have this DLL. See the Mitigation section for more information.

Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

1. Run regedit.exe as Administrator.
2. In Registry Editor, navigate to the following sub key (or create it) and set its DWORD value to 1: HKLM\Software\Microsoft\Windows NT\CurrentVersion\Windows\DisableATMFD, DWORD = 1
3. Close Registry Editor and restart the system.

Impact of workaround

Applications that rely on embedded font technology will not display properly. Renaming ATMFD.DLL could cause certain applications to stop working properly if they use OpenType fonts. Microsoft Windows does not release any OpenType fonts natively. However, third-party applications could install them and they could be affected by this change.

How to undo the workaround.

• Run regedit.exe as Administrator.
• In Registry Editor, navigate to the following sub key and set its DWORD value to 0: HKLM\Software\Microsoft\Windows NT\CurrentVersion\Windows\DisableATMFD, DWORD = 0
• Close Registry Editor and restart the system.

Rename ATMFD.DLL

Please Note: This workaround works for Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, and Windows 8.1. ATMFD.DLL is not present in Windows 10 installations starting with Windows 10, version 1709. Newer versions do not have this DLL. See the Mitigation section for more information.

For 32-bit systems:

1. Enter the following commands at an administrative command prompt:

32-bit_Rename_ATMFD.DLL.bat

Download

Code:

cd "%windir%\system32"
takeown.exe /f atmfd.dll
icacls.exe atmfd.dll /save atmfd.dll.acl
icacls.exe atmfd.dll /grant Administrators:(F) 
rename atmfd.dll x-atmfd.dll

2. Restart the system.

For 64-bit systems:

1. Enter the following commands at an administrative command prompt:

64-bit_Rename_ATMFD.DLL.bat

Download

Code:

    cd "%windir%\system32"
    takeown.exe /f atmfd.dll
    icacls.exe atmfd.dll /save atmfd.dll.acl
    icacls.exe atmfd.dll /grant Administrators:(F) 
    rename atmfd.dll x-atmfd.dll
    cd "%windir%\syswow64"
    takeown.exe /f atmfd.dll
    icacls.exe atmfd.dll /save atmfd.dll.acl
    icacls.exe atmfd.dll /grant Administrators:(F) 
    rename atmfd.dll x-atmfd.dll

2. Restart the system.

Impact of workaround

Applications that rely on embedded font technology will not display properly. Renaming ATMFD.DLL could cause certain applications to stop working properly if they use OpenType fonts. Microsoft Windows does not release any OpenType fonts natively. However, third-party applications could install them and they could be affected by this change.

How to undo the workaround

For 32-bit systems:

1. Enter the following commands at an administrative command prompt:

32-bit_Undo.bat

Download

Code:

    cd "%windir%\system32"
    rename x-atmfd.dll atmfd.dll
    icacls.exe atmfd.dll /setowner "NT SERVICE\TrustedInstaller"
    icacls.exe . /restore atmfd.dll.acl

2. Restart the system.

For 64-bit systems:

1. Enter the following commands at an administrative command prompt:

64-bit_Undo.bat

Download

Code:

    cd "%windir%\system32"
    rename x-atmfd.dll atmfd.dll
    icacls.exe atmfd.dll /setowner "NT SERVICE\TrustedInstaller"
    icacls.exe . /restore atmfd.dll.acl
    cd "%windir%\syswow64"
    rename x-atmfd.dll atmfd.dll
    icacls.exe atmfd.dll /setowner "NT SERVICE\TrustedInstaller"
    icacls.exe . /restore atmfd.dll.acl

2. Restart the system.

FAQ

Is there an update to address this vulnerability?
Yes, Microsoft has released the April security updates, which address this vulnerability. See CVE-2020-1020 for download links and more information.

Is Microsoft aware of attacks that attempt to leverage this vulnerability?
Yes, Microsoft is aware of limited, targeted attacks that attempt to leverage this vulnerability.

How would customers receive notification about this issue and updated information from Microsoft when published?
Customers who subscribe to Microsoft Technical Security Notifications will receive a notifications whenever new content is published in Microsoft’s Security Update Guide. Find more information about these notifications here: Technical Security Notifications.

Do I need an ESU license to receive the update for Windows 7, Windows Server 2008 and Windows Server 2008 R2 for this vulnerability?
Yes, to receive the security update for this vulnerability for Windows 7, Windows Server 2008, or Windows Server 2008 R2 you must have an ESU licence. See 4522133 for more information.

Why is this update not being released for all Windows 7 customers?
Windows 7 reached end of support on January 14, 2020. For more information on Microsoft lifecycle policies, please visit Life Cycle.

Is the Outlook Preview Pane an attack vector for this vulnerability?
No, the Outlook Preview Pane is NOT an attack vector for this vulnerability

Is the Windows Explorer Preview Pane an attack vector for this vulnerability?
Yes, the Windows Preview Pane is an attack vector for this vulnerability

Is Enhanced Security Configuration, which is on by default on Windows Servers, a mitigation for this vulnerability?
No, Enhanced Security Configuration does not mitigate this vulnerability.

Acknowledgements

Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure.

See acknowledgements 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

Version	Date	Description
1.0	03/23/2020	Information published.
1.1	03/23/2020	Added clarifying information to the mitigation. This is an information change only.
1.2	03/24/2020	Added information to the executive summary to clarify targets of attacks. This is an informational change only.
1.3	03/24/2020	Updated the severity of the Windows 10 client and server products to Important. This is an informational change only.
1.4	03/26/2020	Updated Workaround information. This is an informational change only.
1.5	03/27/2020	Updated Workaround information. This is an informational change only.
2.0	04/14/2020	Updated first FAQ to state that CVE-2020-1020 has now been issued to address this vulnerability. This is an informational change only.

Source: https://portal.msrc.microsoft.com/en...sory/ADV200006

Posted By: Brink
23 Mar 2020