Mitigate threats by using Windows 10 security features

Applies to:

• Windows 10

This topic provides an overview of some of the software and firmware threats faced in the current security landscape, and the mitigations that Windows 10 offers in response to these threats. For information about related types of protection offered by Microsoft, see Related topics.

This topic focuses on pre-breach mitigations aimed at device protection and threat resistance. These protections work with other security defenses in Windows 10, as shown in the following illustration:

Figure 1.  Device protection and threat resistance as part of the Windows 10 security defenses

The security threat landscape

Today's security threat landscape is one of aggressive and tenacious threats. In previous years, malicious attackers mostly focused on gaining community recognition through their attacks or the thrill of temporarily taking a system offline. Since then, attacker's motives have shifted toward making money, including holding devices and data hostage until the owner pays the demanded ransom. Modern attacks increasingly focus on large-scale intellectual property theft; targeted system degradation that can result in financial loss; and now even cyberterrorism that threatens the security of individuals, businesses, and national interests all over the world. These attackers are typically highly trained individuals and security experts, some of whom are in the employ of nation states that have large budgets and seemingly unlimited human resources. Threats like these require an approach that can meet this challenge.

In recognition of this landscape, Windows 10 Creator's Update (Windows 10, version 1703) includes multiple security features that were created to make it difficult (and costly) to find and exploit many software vulnerabilities. These features are designed to:

• Eliminate entire classes of vulnerabilities

• Break exploitation techniques

• Contain the damage and prevent persistence

• Limit the window of opportunity to exploit

The following sections provide more detail about security mitigations in Windows 10, version 1703.

Windows 10 mitigations that you can configure

Windows 10 mitigations that you can configure are listed in the following two tables. The first table covers a wide array of protections for devices and users across the enterprise and the second table drills down into specific memory protections such as Data Execution Prevention. Memory protection options provide specific mitigations against malware that attempts to manipulate memory in order to gain control of a system.

Table 1  Windows 10 mitigations that you can configure

Configurable Windows 10 mitigations designed to help protect against memory manipulation require in-depth understanding of these threats and mitigations and knowledge about how the operating system and applications handle memory. The standard process for maximizing these types of mitigations is to work in a test lab to discover whether a given setting interferes with any applications that you use so that you can deploy settings that maximize protection while still allowing apps to run correctly.

As an IT professional, you can ask application developers and software vendors to deliver applications that include an extra protection called Control Flow Guard (CFG). No configuration is needed in the operating system—the protection is compiled into applications. More information can be found in Control Flow Guard.

Table 2  Configurable Windows 10 mitigations designed to help protect against memory exploits

Windows Defender SmartScreen

Windows Defender SmartScreen notifies users if they click on reported phishing and malware websites, and helps protect them against unsafe downloads or make informed decisions about downloads.

For Windows 10, Microsoft improved SmartScreen (now called Windows Defender SmartScreen) protection capability by integrating its app reputation abilities into the operating system itself, which allows Windows Defender SmartScreen to check the reputation of files downloaded from the Internet and warn users when they're about to run a high-risk downloaded file. The first time a user runs an app that originates from the Internet, Windows Defender SmartScreen checks the reputation of the application by using digital signatures and other factors against a service that Microsoft maintains. If the app lacks a reputation or is known to be malicious, Windows Defender SmartScreen warns the user or blocks execution entirely, depending on how the administrator has configured Microsoft Intune or Group Policy settings.

For more information, see Microsoft Defender SmartScreen overview.

Microsoft Defender Antivirus

Microsoft Defender Antivirus in Windows 10 uses a multi-pronged approach to improve anti-malware:

• Tamper proofing helps guard Microsoft Defender Antivirus itself against malware attacks. For example, Microsoft Defender Antivirus uses Protected Processes, which prevents untrusted processes from attempting to tamper with Microsoft Defender Antivirus components, its registry keys, and so on. (Protected Processes is described later in this topic.)

• Cloud-delivered protection helps detect and block new malware within seconds, even if the malware has never been seen before. The service, available as of Windows 10, version 1703, uses distributed resources and machine learning to deliver protection to endpoints at a rate that is far faster than traditional signature updates.

• Rich local context improves how malware is identified. Windows 11 informs Microsoft Defender Antivirus not only about content like files and processes but also where the content came from, where it has been stored, and more. The information about source and history enables Microsoft Defender Antivirus to apply different levels of scrutiny to different content.

• Extensive global sensors help keep Microsoft Defender Antivirus current and aware of even the newest malware. This up-to-date status is accomplished in two ways: by collecting the rich local context data from end points and by centrally analyzing that data.

• Enterprise-level features give IT pros the tools and configuration options necessary to make Microsoft Defender Antivirus an enterprise-class anti-malware solution.

For more information, see Windows Defender in Windows 10 and Windows Defender Overview for Windows Server.

For information about Microsoft Defender for Endpoint, a service that helps enterprises to detect, investigate, and respond to advanced and targeted attacks on their networks, see Microsoft Defender for Endpoint (resources) and Microsoft Defender for Endpoint (documentation).

Data Execution Prevention

Malware depends on its ability to insert a malicious payload into memory with the hope that it will be executed later. Wouldn't it be great if you could prevent malware from running if it wrote to an area that has been allocated solely for the storage of information?

Data Execution Prevention (DEP) does exactly that, by substantially reducing the range of memory that malicious code can use for its benefit. DEP uses the No eXecute bit on modern CPUs to mark blocks of memory as read-only so that those blocks can't be used to execute malicious code that may be inserted through a vulnerability exploit.

To use Task Manager to see apps that use DEP

1. Open Task Manager: Press Ctrl+Alt+Del and select Task Manager, or search the Start screen.

2. Click More Details (if necessary), and then click the Details tab.

3. Right-click any column heading, and then click Select Columns.

4. In the Select Columns dialog box, select the last Data Execution Prevention check box.

5. Click OK.

You can now see which processes have DEP enabled.

Figure 2.  Processes on which DEP has been enabled in Windows 10

You can use Control Panel to view or change DEP settings.

To use Control Panel to view or change DEP settings on an individual PC

1. Open Control Panel, System: click Start, type Control Panel System, and press ENTER.

2. Click Advanced system settings, and then click the Advanced tab.

3. In the Performance box, click Settings.

4. In Performance Options, click the Data Execution Prevention tab.

5. Select an option:

   • Turn on DEP for essential Windows programs and services only

   • Turn on DEP for all programs and services except those I select. If you choose this option, use the Add and Remove buttons to create the list of exceptions for which DEP won't be turned on.

To use Group Policy to control DEP settings

You can use the Group Policy setting called Process Mitigation Options to control DEP settings. A few applications have compatibility problems with DEP, so be sure to test for your environment. To use the Group Policy setting, see Override Process Mitigation Options to help enforce app-related security policies.

Structured Exception Handling Overwrite Protection

Structured Exception Handling Overwrite Protection (SEHOP) helps prevent attackers from being able to use malicious code to exploit the Structured Exception Handling (SEH), which is integral to the system and allows (non-malicious) apps to handle exceptions appropriately. Because this protection mechanism is provided at run-time, it helps to protect applications regardless of whether they've been compiled with the latest improvements.

You can use the Group Policy setting called Process Mitigation Options to control the SEHOP setting. A few applications have compatibility problems with SEHOP, so be sure to test for your environment. To use the Group Policy setting, see Override Process Mitigation Options to help enforce app-related security policies.

Address Space Layout Randomization

One of the most common techniques used to gain access to a system is to find a vulnerability in a privileged process that is already running, guess or find a location in memory where important system code and data have been placed, and then overwrite that information with a malicious payload. Any malware that could write directly to the system memory could overwrite it in well-known and predictable locations.

Address Space Layout Randomization (ASLR) makes that type of attack much more difficult because it randomizes how and where important data is stored in memory. With ASLR, it's more difficult for malware to find the specific location it needs to attack. Figure 3 illustrates how ASLR works by showing how the locations of different critical Windows components can change in memory between restarts.

Figure 3.  ASLR at work

Windows 10 applies ASLR holistically across the system and increases the level of entropy many times compared with previous versions of Windows to combat sophisticated attacks such as heap spraying. 64-bit system and application processes can take advantage of a vastly increased memory space, which makes it even more difficult for malware to predict where Windows 10 stores vital data. When used on systems that have TPMs, ASLR memory randomization will be increasingly unique across devices, which makes it even more difficult for a successful exploit that works on one system to work reliably on another.

You can use the Group Policy setting called Process Mitigation Options to control ASLR settings ("Force ASLR" and "Bottom-up ASLR"), as described in Override Process Mitigation Options to help enforce app-related security policies.

Mitigations that are built in to Windows 10

Windows 10 provides many threat mitigations to protect against exploits that are built into the operating system and need no configuration within the operating system. The subsequent table describes some of these mitigations.

Control Flow Guard (CFG) is a mitigation that doesn't need configuration within the operating system, but does require an application developer to configure the mitigation into the application when it's compiled. CFG is built into Microsoft Edge, IE11, and other areas in Windows 10, and can be built into many other applications when they're compiled.

Table 3   Windows 10 mitigations to protect against memory exploits – no configuration needed

SMB hardening improvements for SYSVOL and NETLOGON shares

In Windows 10 and Windows Server 2016, client connections to the Active Directory Domain Services default SYSVOL and NETLOGON shares on domain controllers require Server Message Block (SMB) signing and mutual authentication (such as Kerberos). This requirement reduces the likelihood of man-in-the-middle attacks. If SMB signing and mutual authentication are unavailable, a computer running Windows 10 or Windows Server 2016 won't process domain-based Group Policy and scripts.

Protected Processes

Most security controls are designed to prevent the initial infection point. However, despite all the best preventative controls, malware might eventually find a way to infect the system. So, some protections are built to place limits on malware that gets on the device. Protected Processes creates limits of this type.

With Protected Processes, Windows 10 prevents untrusted processes from interacting or tampering with those processes that have been specially signed. Protected Processes defines levels of trust for processes. Less trusted processes are prevented from interacting with and therefore attacking more trusted processes. Windows 10 uses Protected Processes more broadly across the operating system, and, as in Windows 8.1, implements them in a way that can be used by third-party anti-malware vendors, as described in Protecting Anti-Malware Services. This ease in use helps make the system and anti-malware solutions less susceptible to tampering by malware that does manage to get on the system.

Universal Windows apps protections

When users download Universal Windows apps from the Microsoft Store, it's unlikely that they'll encounter malware because all apps go through a careful screening process before being made available in the store. Apps that organizations build and distribute through sideloading processes will need to be reviewed internally to ensure that they meet organizational security requirements.

Regardless of how users acquire Universal Windows apps, they can use them with increased confidence. Universal Windows apps run in an AppContainer sandbox with limited privileges and capabilities. For example, Universal Windows apps have no system-level access, have tightly controlled interactions with other apps, and have no access to data unless the user explicitly grants the application permission.

In addition, all Universal Windows apps follow the security principle of least privilege. Apps receive only the minimum privileges they need to perform their legitimate tasks, so even if an attacker exploits an app, the damage the exploit can do is severely limited and should be contained within the sandbox. The Microsoft Store displays the exact capabilities the app requires (for example, access to the camera), along with the app's age rating and publisher.

Windows heap protections

The heap is a location in memory that Windows uses to store dynamic application data. Windows 10 continues to improve on earlier Windows heap designs by further mitigating the risk of heap exploits that could be used as part of an attack.

Windows 10 has several important improvements to the security of the heap:

• Heap metadata hardening for internal data structures that the heap uses, to improve protections against memory corruption.

• Heap allocation randomization, that is, the use of randomized locations and sizes for heap memory allocations, making it more difficult for an attacker to predict the location of critical memory to overwrite. Specifically, Windows 10 adds a random offset to the address of a newly allocated heap, which makes the allocation much less predictable.

• Heap guard pages before and after blocks of memory, which work as trip wires. If an attacker attempts to write past a block of memory (a common technique known as a buffer overflow), the attacker will have to overwrite a guard page. Any attempt to modify a guard page is considered a memory corruption, and Windows 10 responds by instantly terminating the app.

Kernel pool protections

The operating system kernel in Windows sets aside two pools of memory, one that remains in physical memory ("nonpaged pool") and one that can be paged in and out of physical memory ("paged pool"). There are many mitigations that have been added over time, such as process quota pointer encoding; lookaside, delay free, and pool page cookies; and PoolIndex bounds checks. Windows 10 adds multiple "pool hardening" protections, such as integrity checks, that help protect the kernel pool against more advanced attacks.

In addition to pool hardening, Windows 10 includes other kernel hardening features:

• Kernel DEP and Kernel ASLR: Follow the same principles as Data Execution Prevention and Address Space Layout Randomization, described earlier in this topic.

• Font parsing in AppContainer: Isolates font parsing in an AppContainer sandbox.

• Disabling of NT Virtual DOS Machine (NTVDM): The old NTVDM kernel module (for running 16-bit applications) is disabled by default, which neutralizes the associated vulnerabilities. (Enabling NTVDM decreases protection against Null dereference and other exploits.)

• Supervisor Mode Execution Prevention (SMEP): Helps prevent the kernel (the "supervisor") from executing code in user pages, a common technique used by attackers for local kernel elevation of privilege (EOP). This configuration requires processor support found in Intel Ivy Bridge or later processors, or ARM with PXN support.

• Safe unlinking: Helps protect against pool overruns that are combined with unlinking operations to create an attack. Windows 10 includes global safe unlinking, which extends heap and kernel pool safe unlinking to all usage of LIST_ENTRY and includes the "FastFail" mechanism to enable rapid and safe process termination.

• Memory reservations: The lowest 64 KB of process memory is reserved for the system. Apps aren't allowed to allocate that portion of the memory. This allocation for the system makes it more difficult for malware to use techniques such as "NULL dereference" to overwrite critical system data structures in memory.

Control Flow Guard

When applications are loaded into memory, they're allocated space based on the size of the code, requested memory, and other factors. When an application begins to execute code, it calls the other code located in other memory addresses. The relationships between the code locations are well known—they're written in the code itself—but previous to Windows 10, the flow between these locations wasn't enforced, which gave attackers the opportunity to change the flow to meet their needs.

This kind of threat is mitigated in Windows 10 through the Control Flow Guard (CFG) feature. When a trusted application that was compiled to use CFG calls code, CFG verifies that the code location called is trusted for execution. If the location isn't trusted, the application is immediately terminated as a potential security risk.

An administrator can't configure CFG; rather, an application developer can take advantage of CFG by configuring it when the application is compiled. Consider asking application developers and software vendors to deliver trustworthy Windows applications compiled with CFG enabled. For example, it can be enabled for applications written in C or C++, or applications compiled using Visual Studio 2015. For information about enabling CFG for a Visual Studio 2015 project, see Control Flow Guard.

Browsers are a key entry point for attacks, so Microsoft Edge, IE, and other Windows features take full advantage of CFG.

Microsoft Edge and Internet Explorer 11

Browser security is a critical component of any security strategy, and for good reason: the browser is the user's interface to the Internet, an environment with many malicious sites and content waiting to attack. Most users can't perform at least part of their job without a browser, and many users are reliant on one. This reality has made the browser the common pathway from which malicious hackers initiate their attacks.

All browsers enable some amount of extensibility to do things beyond the original scope of the browser. Two common examples are Flash and Java extensions that enable their respective applications to run inside a browser. The security of Windows 10 for the purposes of web browsing and applications, especially for these two content types, is a priority.

Windows 10 includes an entirely new browser, Microsoft Edge. Microsoft Edge is more secure in multiple ways, especially:

• Smaller attack surface; no support for non-Microsoft binary extensions. Multiple browser components with vulnerable attack surfaces have been removed from Microsoft Edge. Components that have been removed include legacy document modes and script engines, Browser Helper Objects (BHOs), ActiveX controls, and Java. However, Microsoft Edge supports Flash content and PDF viewing by default through built-in extensions.

• Runs 64-bit processes. A 64-bit PC running an older version of Windows often runs in 32-bit compatibility mode to support older and less secure extensions. When Microsoft Edge runs on a 64-bit PC, it runs only 64-bit processes, which are much more secure against exploits.

• Includes Memory Garbage Collection (MemGC). This feature helps protect against use-after-free (UAF) issues.

• Designed as a Universal Windows app. Microsoft Edge is inherently compartmentalized and runs in an AppContainer that sandboxes the browser from the system, data, and other apps. IE11 on Windows 10 can also take advantage of the same AppContainer technology through Enhanced Protect Mode. However, because IE11 can run ActiveX and BHOs, the browser and sandbox are susceptible to a much broader range of attacks than Microsoft Edge.

• Simplifies security configuration tasks. Because Microsoft Edge uses a simplified application structure and a single sandbox configuration, there are fewer required security settings. In addition, Microsoft Edge default settings align with security best practices, making it more secure by default.

In addition to Microsoft Edge, Microsoft includes IE11 in Windows 10, primarily for backwards-compatibility with websites and with binary extensions that don't work with Microsoft Edge. You can't configure it as the primary browser but rather as an optional or automatic switchover. We recommend using Microsoft Edge as the primary web browser because it provides compatibility with the modern web and the best possible security.

For sites that require IE11 compatibility, including those sites that require binary extensions and plug-ins, enable Enterprise mode and use the Enterprise Mode Site List to define which sites have the dependency. With this configuration, when Microsoft Edge identifies a site that requires IE11, users will automatically be switched to IE11.

Functions that software vendors can use to build mitigations into apps

Some of the protections available in Windows 10 are provided through functions that can be called from apps or other software. Such software is less likely to provide openings for exploits. If you're working with a software vendor, you can request that they include these security-oriented functions in the application. The following table lists some types of mitigations and the corresponding security-oriented functions that can be used in apps.

Table 4   Functions available to developers for building mitigations into apps

Understanding Windows 10 in relation to the Enhanced Mitigation Experience Toolkit

You might already be familiar with the Enhanced Mitigation Experience Toolkit (EMET), which has since 2009 offered various exploit mitigations, and an interface for configuring those mitigations. You can use this section to understand how EMET mitigations relate to those mitigations in Windows 10. Many of EMET's mitigations have been built into Windows 10, some with extra improvements. However, some EMET mitigations carry high-performance cost, or appear to be relatively ineffective against modern threats, and therefore haven't been brought into Windows 10.

Because many of EMET's mitigations and security mechanisms already exist in Windows 10 and have been improved, particularly the ones assessed to have high effectiveness at mitigating known bypasses, version 5.5x has been announced as the final major version release for EMET (see Enhanced Mitigation Experience Toolkit).

The following table lists EMET features in relation to Windows 10 features.

Table 5   EMET features in relation to Windows 10 features

Converting an EMET XML settings file into Windows 10 mitigation policies

One of EMET's strengths is that it allows you to import and export configuration settings for EMET mitigations as an XML settings file for straightforward deployment. To generate mitigation policies for Windows 10 from an EMET XML settings file, you can install the ProcessMitigations PowerShell module. In an elevated PowerShell session, run this cmdlet:

Install-Module -Name ProcessMitigations

The Get-ProcessMitigation cmdlet gets the current mitigation settings from the registry or from a running process, or it can save all settings to an XML file.

To get the current settings on all running instances of notepad.exe:

Get-ProcessMitigation -Name notepad.exe -RunningProcess

To get the current settings in the registry for notepad.exe:

Get-ProcessMitigation -Name notepad.exe

To get the current settings for the running process with pid 1304:

Get-ProcessMitigation -Id 1304

To get the all process mitigation settings from the registry and save them to the xml file settings.xml:

Get-ProcessMitigation -RegistryConfigFilePath settings.xml

The Set-ProcessMitigation cmdlet can enable and disable process mitigations or set them in bulk from an XML file.

To get the current process mitigation for "notepad.exe" from the registry and then enable MicrosoftSignedOnly and disable MandatoryASLR:

Set-ProcessMitigation -Name Notepad.exe -Enable MicrosoftSignedOnly -Disable MandatoryASLR

To set the process mitigations from an XML file (which can be generated from get-ProcessMitigation -RegistryConfigFilePath settings.xml):

Set-ProcessMitigation -PolicyFilePath settings.xml

To set the system default to be MicrosoftSignedOnly:

Set-ProcessMitigation -System -Enable MicrosoftSignedOnly

The ConvertTo-ProcessMitigationPolicy cmdlet converts mitigation policy file formats. The syntax is:

ConvertTo-ProcessMitigationPolicy -EMETFilePath <String> -OutputFilePath <String> [<CommonParameters>]

Examples:

• Convert EMET settings to Windows 10 settings: You can run ConvertTo-ProcessMitigationPolicy and provide an EMET XML settings file as input, which will generate a result file of Windows 10 mitigation settings. For example:

  ConvertTo-ProcessMitigationPolicy -EMETFilePath policy.xml -OutputFilePath result.xml
  

• Audit and modify the converted settings (the output file): More cmdlets let you apply, enumerate, enable, disable, and save settings in the output file. For example, this cmdlet enables SEHOP and disables MandatoryASLR and DEPATL registry settings for Notepad:

  Set-ProcessMitigation -Name notepad.exe -Enable SEHOP -Disable MandatoryASLR,DEPATL
  

• Convert Attack surface reduction (ASR) settings to a Code Integrity policy file: If the input file contains any settings for EMET's Attack surface reduction (ASR) mitigation, the converter will also create a Code Integrity policy file. In this case, you can complete the merging, auditing, and deployment process for the Code Integrity policy. For more information, see Deploying App Control for Business policies. This completion will enable protections on Windows 10 equivalent to EMET's ASR protections.

• Convert Certificate Trust settings to enterprise certificate pinning rules: If you have an EMET "Certificate Trust" XML file (pinning rules file), you can also use ConvertTo-ProcessMitigationPolicy to convert the pinning rules file into an enterprise certificate pinning rules file. Then you can finish enabling that file as described in Enterprise Certificate Pinning. For example:

  ConvertTo-ProcessMitigationPolicy -EMETfilePath certtrustrules.xml -OutputFilePath enterprisecertpinningrules.xml
  

EMET-related products

Microsoft Consulting Services (MCS) and Microsoft Support/Premier Field Engineering (PFE) offer a range of options for EMET, support for EMET, and EMET-related reporting and auditing products such as the EMET Enterprise Reporting Service (ERS). For any enterprise customers who use such products today or who are interested in similar capabilities, we recommend evaluating Microsoft Defender for Endpoint.

Related topics

• Security and Assurance in Windows Server 2016
• Microsoft Defender for Endpoint - resources
• Microsoft Microsoft Defender for Endpoint - documentation
• Exchange Online Advanced Threat Protection Service Description
• Microsoft Defender for Office 365
• Microsoft Malware Protection Center