---
title: Use Attack Surface Reduction rules to prevent malware infection
description: ASR rules can help prevent exploits from using apps and scripts to infect machines with malware
keywords: Attack Surface Reduction, hips, host intrusion prevention system, protection rules, anti-exploit, antiexploit, exploit, infection prevention
search.product: eADQiWindows 10XVcnh
ms.pagetype: security
ms.prod: w10
ms.mktglfcycl: manage
ms.sitesec: library
ms.pagetype: security
localizationpriority: medium
author: iaanw
ms.author: iawilt
ms.date: 08/25/2017
---



# Reduce attack surfaces with Windows Defender Exploit Guard 


**Applies to:**

- Windows 10 Insider Preview 

[!include[Prerelease information](prerelease.md)]

**Audience**

- Enterprise security administrators


**Manageability available with**

- Group Policy
- PowerShell
- Configuration service providers for mobile device management


Attack Surface Reduction helps prevent actions and apps that are typically used by exploit-seeking malware to infect machines. 

It is part of [Windows Defender Exploit Guard](windows-defender-exploit-guard.md).

Attack Surface Reduction works best with [Windows Defender Advanced Threat Protection](../windows-defender-atp/windows-defender-advanced-threat-protection.md) - which gives you detailed reporting into Windows Defender EG events and blocks as part of the usual [alert investigation scenarios](../windows-defender-atp/investigate-alerts-windows-defender-advanced-threat-protection.md).

The feature is comprised of a number of rules, each of which target specific behaviors that are typically used by malware and malicious apps to infect machines, such as:

- Executable files and scripts used in Office apps or web mail that attempt to download or run files
- Scripts that are obfuscated or otherwise suspicious
- Behaviors that apps undertake that are not usually inititated during normal day-to-day work

When a rule is triggered, a notification will be displayed from the Action Center. You can [customize the notification](customize-attack-surface-reduction.md#customize-the-notification) with your company details and contact information. You can also enable the rules individually to customize what techniques the feature monitors.

You can also use [audit mode](audit-windows-defender-exploit-guard.md) to evaluate how Attack Surface Reduction would impact your organization if it were enabled.



## Requirements

The following requirements must be met before Attack Surface Reduction will work:

Windows 10 version | Windows Defender Antivirus
- | -
Insider Preview build 16232 or later (dated July 1, 2017 or later) | [Windows Defender AV real-time protection](../windows-defender-antivirus/configure-real-time-protection-windows-defender-antivirus.md) and [cloud-delivered protection](../windows-defender-antivirus/enable-cloud-protection-windows-defender-antivirus.md) must be enabled


## Review Attack Surface Reduction events in Windows Event Viewer

You can review the Windows event log to see events that are created when an Attack Surface Reduction rule is triggered (or audited):

1. Download the [Exploit Guard Evaluation Package](#) and extract the file *asr-events.xml* to an easily accessible location on the machine.

1. Type **Event viewer** in the Start menu to open the Windows Event Viewer.

2. On the left panel, under **Actions**, click **Import custom view...**

    ![](images/events-import.gif)

3. Navigate to the Exploit Guard Evaluation Package, and select the file *asr-events.xml*. Alternatively, [copy the XML directly](event-views-exploit-guard.md).

4. Click **OK**.

5. This will create a custom view that filters to only show the following events related to Attack Surface Reduction:

 Event ID | Description
-|-
5007 | Event when settings are changed
1122 | Event when rule fires in Audit-mode 
1121 | Event when rule fires in Block-mode 



### Event fields

- **ID**: matches with the Rule-ID that triggered the block/audit.
- **Detection time**: Time of detection
- **Process Name**: The process that performed the "operation" that was blocked/audited
- **Description**: Additional details about the event or audit, including the signature, engine, and product version of Windows Defender Antivirus


 ## In this section

Topic | Description 
---|---
[Evaluate Attack Surface Reduction](evaluate-attack-surface-reduction.md) | Use a tool to see a number of scenarios that demonstrate how the feature works, and what events would typically be created.
[Enable Attack Surface Reduction](enable-attack-surface-reduction.md) | Use Group Policy, PowerShell, or MDM CSPs to enable and manage Attack Surface Reduction in your network.
[Customize Attack Surface Reduction](customize-attack-surface-reduction.md) | Exclude specified files and folders from being evaluated by Attack Surface Reduction and customize the notification that appears on a user's machine when a rule blocks an app or file.