Microsoft Defender Antivirus Security Technical Implementation Guide

This policy setting allows Microsoft Defender configuration to automatically take action on all detected threats. The action to be taken on a particular threat is determined by the combination of the policy-defined action user-defined action and the signature-defined action. If this policy setting is enabled, Microsoft Defender does not automatically take action on the detected threats but prompts users to choose from the actions available for each threat. If this policy setting is disabled or not configured, Microsoft Defender automatically takes action on all detected threats after a nonconfigurable delay of approximately five seconds.

This policy setting allows disabling of scheduled and real-time scanning for files under the paths specified or for the fully qualified resources specified. Paths should be added under the Options for this setting. Each entry must be listed as a name value pair where the name should be a string representation of a path or a fully qualified resource name. As an example, a path might be defined as: "c:\Windows" to exclude all files in this directory. A fully qualified resource name might be defined as: "C:\Windows\App.exe". The value is not used and it is recommended that this be set to 0. Exceptions can be made to allow file/folders that are impacting enterprise applications to be excluded from being scanned. All exclusions should be documented and approved.

This policy setting allows the disabling of scheduled and real-time scanning for any file opened by any of the specified processes. The process itself will not be excluded. To exclude the process, use the Path exclusion. Processes should be added under the options for this setting. Each entry must be listed as a name value pair where the name should be a string representation of the path to the process image. Note that only executables can be excluded. For example, a process might be defined as: "c:\windows\app.exe". The value is not used and it is recommended that this be set to 0.

This setting allows an administrator to specify if Automatic Exclusions feature for Server SKUs should be turned off.

This policy setting configures a local override for the configuration to join Microsoft MAPS. This setting can only be set by Group Policy. If this setting is enabled, the local preference setting will take priority over Group Policy. If this setting is disabled or not configured, Group Policy will take priority over the local preference setting.

This feature ensures the device checks in real time with the Microsoft Active Protection Service (MAPS) before allowing certain content to be run or accessed. If this feature is disabled, the check will not occur, which will lower the protection state of the device. Enabled - The Block at First Sight setting is turned on. Disabled - The Block at First Sight setting is turned off. This feature requires these Group Policy settings to be set as follows: MAPS >> The "Join Microsoft MAPS" must be enabled or the "Block at First Sight" feature will not function. MAPS >> The "Send file samples when further analysis is required" should be set to 1 (Send safe samples) or 3 (Send all samples). Setting to 0 (Always Prompt) will lower the protection state of the device. Setting to 2 (Never send) means the "Block at First Sight" feature will not function. Real-time Protection >> The "Scan all downloaded files and attachments" policy must be enabled or the "Block at First Sight" feature will not function. Real-time Protection >> Do not enable the "Turn off real-time protection" policy or the "Block at First Sight" feature will not function.

This policy setting allows joining Microsoft MAPS. Microsoft MAPS is the online community that helps in choosing how to respond to potential threats. The community also helps stop the spread of new malicious software infections. You can choose to send basic or additional information about detected software. Additional information helps Microsoft create new definitions and protect your computer. This information can include things like location of detected items on your computer if harmful software was removed. The information will be automatically collected and sent. In some instances personal information might unintentionally be sent to Microsoft. However Microsoft will not use this information to identify you or contact you. Possible options are: (0x0) Disabled (default) (0x1) Basic membership (0x2) Advanced membership Basic membership will send basic information to Microsoft about software that has been detected, including where the software came from, the actions that you apply or that are applied automatically, and whether the actions were successful. Advanced membership will send, in addition to basic information, more information to Microsoft about malicious software spyware and potentially unwanted software, including the location of the software file names, how the software operates, and how it has impacted your computer. If this setting is enabled, you will join Microsoft MAPS with the membership specified. If this setting is disabled or do not configured, you will not join Microsoft MAPS. In Windows 10, Basic membership is no longer available, so setting the value to 1 or 2 enrolls the device into Advanced membership.

This policy setting configures behavior of samples submission when opt-in for MAPS telemetry is set. Possible options are: (0x0) Always prompt (0x1) Send safe samples automatically (0x2) Never send (0x3) Send all samples automatically

This policy setting allows the configuration of protocol recognition for network protection against exploits of known vulnerabilities. If this setting is enabled or not configured, protocol recognition will be enabled. If this setting is disabled, protocol recognition will be disabled.

This policy setting configures a local override for the configuration of monitoring for file and program activity on your computer. This setting can only be set by Group Policy. If this setting is enabled, the local preference setting will take priority over Group Policy. If this setting is disabled or not configured, Group Policy will take priority over the local preference setting.

This policy setting configures a local override for the configuration of monitoring for incoming and outgoing file activity. This setting can only be set by Group Policy. If this setting is enabled, the local preference setting will take priority over Group Policy. If this setting is disabled or not configured, Group Policy will take priority over the local preference setting.

This policy setting configures a local override for the configuration of scanning for all downloaded files and attachments. This setting can only be set by Group Policy. If this setting is enabled, the local preference setting will take priority over Group Policy. If this setting is disabled or not configured, Group Policy will take priority over the local preference setting.

This policy setting configures a local override for the configuration of behavior monitoring. This setting can only be set by Group Policy. If this setting is enabled, the local preference setting will take priority over Group Policy. If this setting is disabled or not configured, Group Policy will take priority over the local preference setting.

This policy setting configures a local override for the configuration to turn on real-time protection. This setting can only be set by Group Policy. If this setting is enabled, the local preference setting will take priority over Group Policy. If this setting is disabled or not configured, Group Policy will take priority over the local preference setting.

This policy setting allows the configuration of monitoring for incoming and outgoing files without having to turn off monitoring entirely. It is recommended for use on servers that have a lot of incoming and outgoing file activity but for performance reasons need to have scanning disabled for a particular scan direction. The appropriate configuration should be evaluated based on the server role. Note that this configuration is only honored for NTFS volumes. For any other file system type, full monitoring of file and program activity will be present on those volumes. The options for this setting are mutually exclusive: 0 = Scan incoming and outgoing files (default) 1 = Scan incoming files only 2 = Scan outgoing files only Any other value, or if the value does not exist, resolves to the default (0). If this setting is enabled, the specified type of monitoring will be enabled. If this setting is disabled or not configured, monitoring for incoming and outgoing files will be enabled.

This policy setting allows configuration of monitoring for file and program activity. If this setting is enabled or not configured, monitoring for file and program activity will be enabled. If this setting is disabled, monitoring for file and program activity will be disabled.

This policy setting allows configuration of scanning for all downloaded files and attachments. If this setting is enabled or not configured, scanning for all downloaded files and attachments will be enabled. If this setting is disabled, scanning for all downloaded files and attachments will be disabled.

This policy setting turns off real-time protection prompts for known malware detection. Microsoft Defender Antivirus alerts when malware or potentially unwanted software attempts to install itself or to run on your computer. If this policy setting is enabled, Microsoft Defender Antivirus will not prompt users to take actions on malware detections. If this policy setting is disabled or not configured, Microsoft Defender Antivirus will prompt users to take actions on malware detections.

This policy setting allows configuration of behavior monitoring. If this setting is enabled or not configured, behavior monitoring will be enabled. If this setting is disabled, behavior monitoring will be disabled.

This policy setting allows the configuration of process scanning when real-time protection is turned on. This helps to catch malware, which could start when real-time protection is turned off. If this setting is enabled or not configured, a process scan will be initiated when real-time protection is turned on. If this setting is disabled, a process scan will not be initiated when real-time protection is turned on.

This policy setting allows the configuration of scans for malicious software and unwanted software in archive files such as .ZIP or .CAB files. If this setting is enabled or not configured, archive files will be scanned. If this setting is disabled, archive files will not be scanned.

This policy setting allows the management of whether or not to scan for malicious software and unwanted software in the contents of removable drives such as USB flash drives when running a full scan. If this setting is enabled, removable drives will be scanned during any type of scan. If this setting is disabled or not configured, removable drives will not be scanned during a full scan. Removable drives may still be scanned during quick scan and custom scan.

This policy setting allows specifying the day of the week on which to perform a scheduled scan. The scan can also be configured to run every day or to never run at all. This setting can be configured with the following ordinal number values: (0x0) Every Day (0x1) Sunday (0x2) Monday (0x3) Tuesday (0x4) Wednesday (0x5) Thursday (0x6) Friday (0x7) Saturday (0x8) Never (default) If this setting is enabled, a scheduled scan will run at the frequency specified. If this setting is disabled or not configured, a scheduled scan will run at a default frequency.

This policy setting allows the configuration of e-mail scanning. When e-mail scanning is enabled, the engine will parse the mailbox and mail files according to their specific format in order to analyze the mail bodies and attachments. Several e-mail formats are currently supported, for example: pst (Outlook), dbx mbx mime (Outlook Express), binhex (Mac). If this setting is enabled, e-mail scanning will be enabled. If this setting is disabled or not configured, e-mail scanning will be disabled.

This policy setting allows specifying the day of the week on which to check for definition updates. The check can also be configured to run every day or to never run at all. This setting can be configured with the following ordinal number values: (0x0) Every Day (default) (0x1) Sunday (0x2) Monday (0x3) Tuesday (0x4) Wednesday (0x5) Thursday (0x6) Friday (0x7) Saturday (0x8) Never If this setting is enabled, the check for definition updates will occur at the frequency specified. If this setting is disabled or not configured, the check for definition updates will occur at a default frequency.

This policy setting allows the customization of which automatic remediation action will be taken for each threat alert level. Threat alert levels should be added under the Options for this setting. Each entry must be listed as a name value pair. The name defines a threat alert level. The value contains the action ID for the remediation action that should be taken. Valid threat alert levels are: 1 = Low 2 = Medium 4 = High 5 = Severe Valid remediation action values are: 2 = Quarantine 3 = Remove 6 = Ignore

This rule blocks the following file types from being run or launched from an email seen in either Microsoft Outlook or webmail (such as Gmail.com or Outlook.com): Executable files (such as .exe, .dll, or .scr) Script files (such as a PowerShell .ps, VisualBasic .vbs, or JavaScript .js file) Script archive files

Office apps, such as Word or Excel, will not be allowed to create child processes. This is a typical malware behavior, especially for macro-based attacks that attempt to use Office apps to launch or download malicious executables.

This rule targets typical behaviors used by suspicious and malicious add-ons and scripts (extensions) that create or launch executable files. This is a typical malware technique. Extensions will be blocked from being used by Office apps. Typically these extensions use the Windows Scripting Host (.wsh files) to run scripts that automate certain tasks or provide user-created add-on features.

Office apps, such as Word, Excel, or PowerPoint, will not be able to inject code into other processes. This is typically used by malware to run malicious code in an attempt to hide the activity from antivirus scanning engines.

JavaScript and VBScript scripts can be used by malware to launch other malicious apps. This rule prevents these scripts from being allowed to launch apps, thus preventing malicious use of the scripts to spread malware and infect machines.

Malware and other threats can attempt to obfuscate or hide their malicious code in some script files. This rule prevents scripts that appear to be obfuscated from running. It uses the AntiMalwareScanInterface (AMSI) to determine if a script is potentially obfuscated and then blocks such a script or blocks scripts when an attempt is made to access them.

This rule blocks potentially malicious behavior by not allowing macro code to execute routines in the Win 32 dynamic link library (DLL).

Enable Microsoft Defender Exploit Guard network protection to prevent employees from using any application to access dangerous domains that may host phishing scams, exploit-hosting sites, and other malicious content on the internet.

This policy setting allows the customization of which automatic remediation action will be taken for each threat alert level. Threat alert levels should be added under the Options for this setting. Each entry must be listed as a name value pair. The name defines a threat alert level. The value contains the action ID for the remediation action that should be taken. Valid threat alert levels are: 1 = Low 2 = Medium 4 = High 5 = Severe Valid remediation action values are: 2 = Quarantine 3 = Remove 6 = Ignore

This policy setting allows the customization of which automatic remediation action will be taken for each threat alert level. Threat alert levels should be added under the Options for this setting. Each entry must be listed as a name value pair. The name defines a threat alert level. The value contains the action ID for the remediation action that should be taken. Valid threat alert levels are: 1 = Low 2 = Medium 4 = High 5 = Severe Valid remediation action values are: 2 = Quarantine 3 = Remove 6 = Ignore

This policy setting allows the customization of which automatic remediation action will be taken for each threat alert level. Threat alert levels should be added under the Options for this setting. Each entry must be listed as a name value pair. The name defines a threat alert level. The value contains the action ID for the remediation action that should be taken. Valid threat alert levels are: 1 = Low 2 = Medium 4 = High 5 = Severe Valid remediation action values are: 2 = Quarantine 3 = Remove 6 = Ignore

This policy setting prevents Adobe Reader from launching other processes, which can help mitigate security risks associated with malicious PDF files.

This policy setting helps prevent credential stealing by locking down Local Security Authority Subsystem Service (LSASS).

This policy setting helps prevents unsigned or untrusted executable files from running from USB removable drives, including SD cards. Blocked file types include executable files (such as .exe, .dll, or .scr).

This policy setting provides an extra layer of protection against ransomware. It uses both client and cloud heuristics to determine whether a file resembles ransomware. This rule doesn't block files that have one or more of the following characteristics: - The file is found to be unharmful in the Microsoft cloud. - The file is a valid signed file. - The file is prevalent enough to not be considered as ransomware. - The rule tends to err on the side of caution to prevent ransomware.

This policy setting blocks processes created through PsExec and WMI from running. Both PsExec and WMI can remotely execute code. There is a risk of malware abusing functionality of PsExec and WMI for command and control purposes, or to spread an infection throughout an organization's network.

This policy setting prevents malware from abusing WMI to attain persistence on a device. Fileless threats employ various tactics to stay hidden, to avoid being seen in the file system, and to gain periodic execution control. Some threats can abuse the WMI repository and event model to stay hidden.

This policy setting blocks executable files, such as .exe, .dll, or .scr, from launching. Thus, launching untrusted or unknown executable files can be risky, as it might not be initially clear if the files are malicious.

This policy setting prevents Outlook from creating child processes while still allowing legitimate Outlook functions. This rule protects against social engineering attacks and prevents exploiting code from abusing vulnerabilities in Outlook. It also protects against Outlook rules and forms exploits that attackers can use when a user's credentials are compromised.

This policy setting prevents an application from writing a vulnerable signed driver to disk. Vulnerable signed drivers can be exploited by local applications that have sufficient privileges to gain access to the kernel. Vulnerable signed drivers enable attackers to disable or circumvent security solutions, eventually leading to system compromise. The Block abuse of exploited vulnerable signed drivers rule does not block a driver already existing on the system from being loaded.

This policy setting configures how locally defined lists are combined or merged with globally defined lists. This setting applies to exclusion lists, specified remediation lists, and attack surface reduction.

Disabled (Default): If this setting is not configured or disabled, local admins can see exclusions in the Windows Security App or via PowerShell. Enabled: If this setting is enabled, local admins no longer see the exclusion list in Windows Security App or via PowerShell.O13. Note: Applying this setting will not remove exclusions, it only prevents them from being visible to local admins. This is reflected in?Get-MpPreference.I13.

In Microsoft Defender Antivirus, randomize the start time of the scan to any interval from 0 to 23 hours. By default, scheduled tasks begin at a random time within four hours of the time specified in Task Scheduler.

The Family options section contains links to settings and further information for parents of a Windows PC. It is not intended for enterprise or business environments. This section can be hidden from users of the machine. This option can be useful if you do not want users in the organization to see or have access to this section.

This policy drives the ability to enforce Indicators of Compromise (IoC) by using file hash allow/block indicators.

When Microsoft Defender Antivirus finds a suspicious file, it can prevent the file from running while it queries the Microsoft Defender Antivirus cloud service. The default period that the file is blocked is 10 seconds. Extending the cloud block timeout period can help ensure there is enough time to receive a proper determination from the Microsoft Defender Antivirus cloud service.

Always-on protection consists of real-time protection, behavior monitoring, and heuristics to identify malware based on known suspicious and malicious activities. These activities include events, such as processes making unusual changes to existing files, modifying or creating automatic startup registry keys and startup locations (also known as autostart extensibility points, or ASEPs), and other changes to the file system or file structure.

Always-on protection consists of real-time protection, behavior monitoring, and heuristics to identify malware based on known suspicious and malicious activities. These activities include events, such as processes making unusual changes to existing files, modifying or creating automatic startup registry keys and startup locations (also known as autostart extensibility points, or ASEPs), and other changes to the file system or file structure.

Microsoft's Exploit Guard comprises several techniques to defend against phishing attacks and malware. These include controlled folder access, attack surface reduction, and network protection.

EDR in block mode allows Microsoft Defender Antivirus to take actions on post-breach, behavioral EDR detections. EDR in block mode is integrated with threat and vulnerability management capabilities.

Microsoft Defender Antivirus logs "Dynamic Signature dropped" events when it blocks or removes a file based on a dynamically updated signature, but the signature itself is dropped, meaning it was not fully processed or applied. This can indicate a potential issue with signature updates or the system's ability to handle them.

In Microsoft Defender Antivirus, when an exclusion for a file or folder is created, it will generally be skipped during both real-time protection and on-demand scans (including quick scans and full scans). However, with newer releases, the option exists to configure quick scans to include files and directories that are otherwise excluded from real-time protection.

If a site URL has an unknown or uncertain reputation, a toast notification presents the user with the following options: - Ok: The toast notification is released (removed), and the attempt to access the site is ended. - Unblock: The user has access to the site for 24 hours, at which point the block is reenabled. The user can continue to use Unblock to access the site until such time that the administrator prohibits (blocks) the site, thus removing the option to Unblock. - Feedback: The toast notification presents the user with a link to submit a ticket, which the user can use to submit feedback to the administrator in an attempt to justify access to the site.

Network protection includes performance optimization that allows block mode to asynchronously inspect long-lived connections, which might provide a performance improvement. This optimization can also help with app compatibility problems.

This policy setting manages whether Microsoft Defender Antivirus scans packed executables. Packed executables are executable files that contain compressed code.

Always-on protection consists of real-time protection, behavior monitoring, and heuristics to identify malware based on known suspicious and malicious activities.

Cloud protection in Microsoft Defender Antivirus delivers accurate, real-time, and intelligent protection. Cloud protection should be enabled by default.