File Shield

File Shield is the main layer of Antivirus active protection. It scans programs and files saved on the device for malicious threats as they are opened, run, modified, and saved. File Shield is designed to prevent any detected malware from infecting the system.

We strongly recommend you always keep this shield turned on and only make configuration changes if you have an advanced understanding of malware protection principles.

For Windows configuration options, see below. For macOS configuration options, see macOS File Shield Settings.

Scan Behavior Tab

Scan when executing: Select whether to scan programs, scripts, and/or libraries when the files or programs are executed

Scan when opening: Select whether to scan documents, documents with custom extensions (you input), and/or all files when the documents or files are opened

Scan when writing: Select whether to scan files when writing (default extensions, custom extensions, or all files), and also whether or not to scan files on remote shares or removable media when the files are created or modified

Scan when attaching: Select whether to scan auto-run items and/or diskette boot sectors when removable media is attached

Actions Tab

Control what actions are taken by Avast when a virus, potentially unwanted program (PUP), unwanted tool, or suspicious file is detected.

Main Action/First action to try: Select the first action you want your Antivirus to take (for example, if it will first attempt to fix or quarantine the threat, or delete it immediately).

If, for whatever reason, Avast cannot complete the main action, it will attempt the action selected under If the action fails, use.

Notification Options: Choose whether to show notifications when File Shield takes action against a detected threat, and/or to perform the selected action upon restart.

Processing of infected archives: Choose whether to only remove the packed file from the archive (and if that fails, do nothing), remove the packed file from the archive (and if that fails, remove the entire archive), or to remove the entire archive.

Packers Tab

Configure which archive (packer) files Antivirus should try to unpack during the scanning process. Unpacked files can be better analyzed for malware by File Shield. Unpacking a file is the same as extracting a file from an archive. Original archives, including the files contained within, remain intact when being processed by your Shield.

You can select All packers, or specific packer files from the extensive list by checking the boxes.

Sensitivity Tab

Here, you can adjust the sensitivity of the Antivirus scan for File Shield:

• Heuristics Sensitivity: Heuristics enable Antivirus to detect unknown malware by analyzing code for commands that may indicate malicious intent. The default setting is Normal. With higher sensitivity, Antivirus is more likely to detect malware, but also more likely to make false-positive detections that incorrectly identify files as malware.
  • Use code emulation: Choose whether to use code emulations to unpack and test suspected malware in an emulated environment, where the files cannot cause damage to devices.
• Sensitivity: Enable Test whole files to check the whole content of a file instead of the parts typically affected by malicious code. There is usually no need to enable this option, and it will likely impact system performance.
• PUP and suspicious files: Choose whether or not to scan for potentially unwanted programs (PUPs).

Report File

Customize the content of the shield's report file, such as which items are included, the file name, and file type. The report is saved in C:\ProgramData\Avast Software\Avast\report (Windows 7 and higher).

Advanced Settings

You can access these extra settings by clicking Advanced Settings at the bottom of the File Shield settings section. Use the check boxes to enable or disable these settings.

Do not scan verified system DLLs: Select whether or not to scan files belonging to the operating system

Use transient caching: Select whether or not temporary memory stores information about previously scanned items; files scanned once and not detected as threats will not be scanned again until either the system is restarted or the virus definitions are updated

Use persistent caching: Select whether or not files verified as clean (e.g. with a valid digital signature) will be scanned again, even after system restart or virus definitions update

macOS File Shield Settings

These options can be accessed from the Antivirus section by going to the Mac Settings tab and selecting File Shield.

The available settings control whether infected files are moved to Virus Chest and PUPs reported, and allow you to configure exclusions.

Adding File Shield Exclusions

If needed, you can add exclusions to the File Shield scans through the Antivirus Exclusions settings of a selected policy. This can speed up the scans and prevent false-positive detections.

For more information on standard and component-specific exclusions, see Configuring Antivirus Exclusions.

Exclusions for macOS devices are added through the Mac Settings tab (see above).