Customize attack surface reduction rules
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Attack surface reduction rules help prevent actions and apps that are typically used by exploit-seeking malware to infect machines. Attack surface reduction rules are supported on Windows Server 2019 as well as Windows 10 clients.
You can use Group Policy, PowerShell, and MDM CSPs to configure these settings.
Exclude files and folders
You can exclude files and folders from being evaluated by attack surface reduction rules. This means that even if an attack surface reduction rule detects that the file contains malicious behavior, the file will not be blocked from running.
This could potentially allow unsafe files to run and infect your devices. Excluding files or folders can severely reduce the protection provided by attack surface reduction rules. Files that would have been blocked by a rule will be allowed to run, and there will be no report or event recorded.
An exclusion applies to all rules that allow exclusions. You can specify an individual file, folder path, or the fully qualified domain name for a resource, but you cannot limit an exclusion to certain rules.
An exclusion is applied only when when the excluded application or service starts. For example, if you add an exclusion for an update service that is already running, the update service will continue to trigger events until the service is stopped and restarted.
Attack surface reduction supports environment variables and wildcards. For information about using wildcards, see Use wildcards in the file name and folder path or extension exclusion lists. If you are encountering problems with rules detecting files that you believe should not be detected, you should use audit mode first to test the rule.
|Block all Office applications from creating child processes||D4F940AB-401B-4EFC-AADC-AD5F3C50688A|
|Block execution of potentially obfuscated scripts||5BEB7EFE-FD9A-4556-801D-275E5FFC04CC|
|Block Win32 API calls from Office macro||92E97FA1-2EDF-4476-BDD6-9DD0B4DDDC7B|
|Block Office applications from creating executable content||3B576869-A4EC-4529-8536-B80A7769E899|
|Block Office applications from injecting code into other processes||75668C1F-73B5-4CF0-BB93-3ECF5CB7CC84|
|Block executable content from email client and webmail||BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550|
|Block executable files from running unless they meet a prevalence, age, or trusted list criteria||01443614-cd74-433a-b99e-2ecdc07bfc25|
|Use advanced protection against ransomware||c1db55ab-c21a-4637-bb3f-a12568109d35|
|Block credential stealing from the Windows local security authority subsystem (lsass.exe)||9e6c4e1f-7d60-472f-ba1a-a39ef669e4b2|
|Block process creations originating from PSExec and WMI commands||d1e49aac-8f56-4280-b9ba-993a6d77406c|
|Block untrusted and unsigned processes that run from USB||b2b3f03d-6a65-4f7b-a9c7-1c7ef74a9ba4|
|Block Office communication applications from creating child processes||26190899-1602-49e8-8b27-eb1d0a1ce869|
|Block Adobe Reader from creating child processes||7674ba52-37eb-4a4f-a9a1-f0f9a1619a2c|
|Block persistence through WMI event subscription||e6db77e5-3df2-4cf1-b95a-636979351e5b|
See the attack surface reduction topic for details on each rule.
Use Group Policy to exclude files and folders
On your Group Policy management computer, open the Group Policy Management Console, right-click the Group Policy Object you want to configure and click Edit.
In the Group Policy Management Editor go to Computer configuration and click Administrative templates.
Expand the tree to Windows components > Windows Defender Antivirus > Windows Defender Exploit Guard > Attack surface reduction.
Double-click the Exclude files and paths from Attack surface reduction Rules setting and set the option to Enabled. Click Show and enter each file or folder in the Value name column. Enter 0 in the Value column for each item.
Use PowerShell to exclude files and folders
- Type powershell in the Start menu, right-click Windows PowerShell and click Run as administrator
Enter the following cmdlet:
Add-MpPreference -AttackSurfaceReductionOnlyExclusions "<fully qualified path or resource>"
Continue to use
Add-MpPreference -AttackSurfaceReductionOnlyExclusions to add more folders to the list.
Add-MpPreference to append or add apps to the list. Using the
Set-MpPreference cmdlet will overwrite the existing list.
Use MDM CSPs to exclude files and folders
Use the ./Vendor/MSFT/Policy/Config/Defender/AttackSurfaceReductionOnlyExclusions configuration service provider (CSP) to add exclusions.
Customize the notification
See the Windows Security topic for more information about customizing the notification when a rule is triggered and blocks an app or file.
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