Configure and validate exclusions for Microsoft Defender for Endpoint on Linux

Applies to:

• Microsoft Defender for Endpoint Server
• Microsoft Defender for Servers

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This article provides information on how to define antivirus and global exclusions for Microsoft Defender for Endpoint. Antivirus exclusions apply to on-demand scans, real-time protection (RTP), and behavior monitoring (BM). Global exclusions apply to real-time protection (RTP), behavior monitoring (BM), and endpoint detection and response (EDR), thus stopping all the associated antivirus detections, EDR alerts, and visibility for the excluded item.

You can exclude certain files, folders, processes, and process-opened files from Defender for Endpoint on Linux.

Exclusions can be useful to avoid incorrect detections on files or software that are unique or customized to your organization. Global exclusions are useful for mitigating performance issues caused by Defender for Endpoint on Linux.

Supported exclusion scopes

As described in an earlier section, we support two exclusion scopes: antivirus (epp) and global (global) exclusions.

Antivirus exclusions can be used to exclude trusted files and processes from real-time protection while still having EDR visibility. Global exclusions are applied at sensor level and to mute the events that match exclusion conditions early in the flow, before any processing is done, thus stopping all EDR alerts and antivirus detections.

Supported exclusion types

The following table shows the exclusion types supported by Defender for Endpoint on Linux.

File, folder, and process exclusions support the following wildcards:

How to configure the list of exclusions

You can configure exclusions using a management Json configuration, Defender for Endpoint security settings management, or the command line.

Using the management console

In enterprise environments, exclusions can also be managed through a configuration profile. Typically, you would use a configuration management tool like Puppet, Ansible, or another management console to push a file with the name mdatp_managed.json at the location /etc/opt/microsoft/mdatp/managed/. For more information, see Set preferences for Defender for Endpoint on Linux. Please refer to the following sample of mdatp_managed.json.

{
   "exclusionSettings":{
     "exclusions":[
        {
           "$type":"excludedPath",
           "isDirectory":true,
           "path":"/home/*/git<EXAMPLE DO NOT USE>",
           "scopes": [
              "epp"
           ]
        },
        {
           "$type":"excludedPath",
           "isDirectory":true,
           "path":"/run<EXAMPLE DO NOT USE>",
           "scopes": [
              "global"
           ]
        },
        {
           "$type":"excludedPath",
           "isDirectory":false,
           "path":"/var/log/system.log<EXAMPLE DO NOT USE><EXCLUDED IN ALL SCENARIOS>",
           "scopes": [
              "epp", "global"
           ]
        },
        {
           "$type":"excludedFileExtension",
           "extension":".pdf<EXAMPLE DO NOT USE>",
           "scopes": [
              "epp"
           ]
        },
        {
           "$type":"excludedFileName",
           "name":"/bin/cat<EXAMPLE DO NOT USE><NO SCOPE PROVIDED - GLOBAL CONSIDERED>"
        }
     ],
     "mergePolicy":"admin_only"
   }
}

Using Defender for Endpoint security settings management

You can use the Microsoft Intune admin center or the Microsoft Defender portal to manage exclusions as endpoint security policies and assign those policies to Microsoft Entra ID groups. If you're using this method for the first time, make sure to complete the following steps:

1. Configure your tenant to support security settings management

1. In the Microsoft Defender portal, navigate to Settings > Endpoints > Configuration Management > Enforcement Scope, and then select the Linux platform.

2. Tag devices with the MDE-Management tag. Most devices enroll and receive the policy within minutes, although some might take up to 24 hours. For more information, see Learn how to use Intune endpoint security policies to manage Microsoft Defender for Endpoint on devices that aren't enrolled with Intune.

2. Create a Microsoft Entra group

Create a dynamic Microsoft Entra group based on the operating system type to ensure that all devices onboarded to Defender for Endpoint receive the appropriate policies. This dynamic group automatically includes devices managed by Defender for Endpoint, eliminating the need for admins to manually create new policies. For more information, see the following article: Create Microsoft Entra Groups

3. Create an endpoint security policy

1. In the Microsoft Defender portal, go to Endpoints > Configuration management > Endpoint security policies, and then select Create new Policy.

2. For Platform, select Linux.

3. Select the required exclusion template (Microsoft defender global exclusions (AV+EDR) for global exclusions and Microsoft defender antivirus exclusions for antivirus exclusions), and then select Create policy.

4. On the Basics page, enter a name and description for the profile, then choose Next.

5. On the Settings page, expand each group of settings, and configure the settings you want to manage with this profile.

6. When you're done configuring settings, select Next.

7. On the Assignments page, select the groups that receive this profile. Then select Next.

8. On the Review + create page, when you're done, select Save. The new profile is displayed in the list when you select the policy type for the profile you created.

For more information refer: Manage endpoint security policies in Microsoft Defender for Endpoint.

Using the command line

Run the following command to see the available switches for managing exclusions:

mdatp exclusion

This section includes several examples.

Example 1: Add an exclusion for a file extension

You can add an exclusion for a file extension. Keep in mind that extension exclusions aren't supported for the global exclusion scope.

mdatp exclusion extension add --name .txt

Extension exclusion configured successfully

mdatp exclusion extension remove --name .txt

Extension exclusion removed successfully

Example 2: Add or remove a file exclusion

You can add or remove an exclusion for a file. The file path should already be present if you're adding or removing an exclusion with the global scope.

mdatp exclusion file add --path /var/log/dummy.log --scope epp

File exclusion configured successfully

mdatp exclusion file remove --path /var/log/dummy.log --scope epp

File exclusion removed successfully"

mdatp exclusion file add --path /var/log/dummy.log --scope global

File exclusion configured successfully

mdatp exclusion file remove --path /var/log/dummy.log --scope global

File exclusion removed successfully"

Example 3: Add or remove a folder exclusion

You can add or remove an exclusion for a folder.

mdatp exclusion folder add --path /var/log/ --scope epp

Folder exclusion configured successfully

mdatp exclusion folder remove --path /var/log/ --scope epp

Folder exclusion removed successfully

mdatp exclusion folder add --path /var/log/ --scope global

Folder exclusion configured successfully

mdatp exclusion folder remove --path /var/log/ --scope global

Folder exclusion removed successfully

Example 4: Add an exclusion for a second folder

You can add an exclusion for a second folder.

mdatp exclusion folder add --path /var/log/ --scope epp
mdatp exclusion folder add --path /other/folder  --scope global

Folder exclusion configured successfully

Example 5: Add a folder exclusion with a wildcard

You can add an exclusion for a folder with a wildcard. Keep in mind that Wildcards aren't supported while configuring global exclusions.

mdatp exclusion folder add --path "/var/*/tmp"

The previous command excludes paths under */var/*/tmp/*, but not folders that are siblings of *tmp*. For example, */var/this-subfolder/tmp* is excluded, but */var/this-subfolder/log* isn't excluded.

mdatp exclusion folder add --path "/var/" --scope epp

OR

mdatp exclusion folder add --path "/var/*/" --scope epp

The previous command excludes all paths whose parent is */var/*, such as */var/this-subfolder/and-this-subfolder-as-well*.

Folder exclusion configured successfully

Example 6: Add an exclusion for a process

You can add an exclusion for a process.

mdatp exclusion process add --path /usr/bin/cat --scope global 

Process exclusion configured successfully

mdatp exclusion process remove --path /usr/bin/cat  --scope global

Process exclusion removed successfully

mdatp exclusion process add --name cat --scope epp 

Process exclusion configured successfully

mdatp exclusion process remove --name cat --scope epp

Process exclusion removed successfully

Example 7: Add an exclusion for a second process

You can add an exclusion for a second process.

mdatp exclusion process add --name cat --scope epp
mdatp exclusion process add --path /usr/bin/dog --scope global

Process exclusion configured successfully

Validate exclusions lists with the EICAR test file

You can validate that your exclusion lists are working by using curl to download a test file.

In the following Bash snippet, replace test.txt with a file that conforms to your exclusion rules. For example, if you have excluded the .testing extension, replace test.txt with test.testing. If you're testing a path, ensure that you run the command within that path.

curl -o test.txt https://secure.eicar.org/eicar.com.txt

If Defender for Endpoint on Linux reports malware, then the rule isn't working. If there's no report of malware, and the downloaded file exists, then the exclusion is working. You can open the file to confirm that the contents are the same as what is described on the EICAR test file website.

If you don't have Internet access, you can create your own EICAR test file. Write the EICAR string to a new text file with the following Bash command:

echo 'X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*' > test.txt

You can also copy the string into a blank text file and attempt to save it with the file name or in the folder you're attempting to exclude.

Allow a threat

In addition to excluding certain content from being scanned, you can also configure Defender for Endpoint on Linux not to detect some classes of threats, identified by the threat name.

To add a threat name to the allowed list, run the following command:

mdatp threat allowed add --name [threat-name]

To get the name of a detected threat, run the following command:

mdatp threat list

For example, to add EICAR-Test-File (not a virus) to the allowlist, run the following command:

mdatp threat allowed add --name "EICAR-Test-File (not a virus)"

See also

• Microsoft Defender for Endpoint on Linux
• Set preferences for Microsoft Defender for Endpoint on Linux