Running a Boot-time Scan in Avast Antivirus

If you suspect that your PC contains malware, Avast Antivirus allows you to schedule a Boot-Time Scan to run the next time your computer starts. It scans for known types of malware and removes threats before the operating system and other services run.

Boot-Time Scan is an advanced feature designed to use when you suspect a threat in the system, and usually takes some time to run. It does not run automatically or on a regular basis. You need to manually schedule it to run when needed.

Before scheduling and running a Boot-Time Scan, you need to specify how Boot-Time Scan will respond to detected threats. This article also contains information about general Boot-Time Scan settings, which allow you to specify scan sensitivity, and what issue types are detected by Boot-Time Scan.

If malware prevents Avast Antivirus from scheduling Boot-Time Scan in normal mode, you can schedule Boot-Time Scan to run in Safe Mode. For instructions, refer to the following article:

Specify how Boot-Time Scan will respond to detected threats

To specify which action(s) Boot-Time Scan applies when it detects a threat, you need to either enable or disable automatic actions. When you use automatic actions, Boot-Time Scan applies your specified action(s) automatically to all detected threats. Alternatively, when you disable automatic actions, you are prompted during the Boot-Time Scan to manually select an action for each detected threat.

To specify how Boot-Time Scan will respond to detected threats:

  1. Open the Avast Antivirus user interface and select ProtectionVirus Scans.
  2. Click Settings (the gear icon) on the right side of the screen.
  3. Select the Boot-Time Scan tab.
  4. Scroll down to Perform automatic actions during this scan. Either untick this option to disable automatic actions, or ensure this option is ticked to enable automatic actions.
  5. If you enabled automatic actions in the previous step, select your preferred automatic action:
    • Fix automatically (recommended): Avast Antivirus attempts to repair the file. If unsuccessful, it moves the file to the Virus Chest or deletes the file if neither action is successful.
    • Move file to Virus Chest: Avast Antivirus sends the file to the Virus Chest, where it cannot harm your system.
    • Delete file: Avast Antivirus permanently removes the file from your PC.

When you run Boot-Time Scan, Avast Antivirus responds to detected threats according to your preferences.

Use caution when configuring Boot-Time Scan to take automatic actions. In the event that a critical system file is incorrectly identified as malware due to a false positive issue, Boot-Time Scan may delete the file if an automatic action is set up. Though Avast Antivirus has a number of measures designed to prevent such issues, false positives may occur.

Schedule and run Boot-Time Scan

After specifying how Boot-Time Scan will respond to detected threats, follow the instructions below to schedule a Boot-Time Scan:

  1. Open the Avast Antivirus user interface and select ProtectionVirus Scans.
  2. Click the Boot-Time Scan tile.
  3. Click Install specialized definitions, then click Run On Next PC Reboot to run the scan during the next system restart.
When you click Install specialized definitions on the Boot-Time Scan screen, Avast Antivirus downloads all virus definitions from a cloud database. If you skip installing specialized definitions, Boot-Time Scan scans your PC based only on the latest virus definitions that are already downloaded. After clicking Install specialized definitions, you are not offered this option again.
  1. Restart your PC. When the system restarts, a Boot-Time Scan progress screen appears as Windows loads.
  2. For any detected threat, Avast Antivirus applies the action specified in your application settings. If automatic actions are enabled, Avast Antivirus resolves detected issues without any actions required from you. If you disabled automatic actions and a threat is detected, follow the on-screen instructions to manually select which action Avast Antivirus applies.

The scan usually takes several minutes, but the duration varies depending on the speed of your system and the number of files to be scanned. When the scan is completed or skipped, Windows continues booting up.

To skip the scan, press the Esc key on your keyboard.

Adjust Boot-Time Scan settings

  1. Open the Avast Antivirus user interface and select ProtectionVirus Scans.
  2. Click Settings (the gear icon) on the right side of the screen.
  3. Select the Boot-Time Scan tab.
  4. Manage different aspects of your scan:
    1. Sensitivity: use the slider to indicate your preferred level of heuristic sensitivity. Heuristics enable Avast Antivirus to detect unknown malware by analyzing code for commands which may indicate malicious intent.
    2. Scan for potentially unwanted programs (PUPs): ensure this box is ticked if you want Boot-Time Scan to look for programs that are stealthily downloaded with other programs and typically perform unwanted activity.
    3. Unpack archive files: ensure this box is ticked if you want Avast Antivirus to unpack compressed files during the scan.
    4. Scan areas: select All Harddisks or System drive to specify which data space you want the scan to analyze.
    5. Auto start programs: allows Avast Antivirus to scan programs that automatically start when you turn on your computer.
    6. Actions: configure automatic actions to any threats detected by Boot-Time Scan.
  • Avast Free Antivirus 20.x
  • Avast Premium Security 20.x
  • Avast Omni 1.x
  • Microsoft Windows 10 Home / Pro / Enterprise / Education - 32 / 64-bit
  • Microsoft Windows 8.1 / Pro / Enterprise - 32 / 64-bit
  • Microsoft Windows 8 / Pro / Enterprise - 32 / 64-bit
  • Microsoft Windows 7 Home Basic / Home Premium / Professional / Enterprise / Ultimate - Service Pack 1, 32 / 64-bit

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