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 is manually scheduled to run as needed, not on a regular basis.

If malware prevents Avast 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:

Schedule and run Boot-Time Scan

  1. Open the Avast 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 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.
  4. Restart your PC. When the system restarts, a Boot-Time Scan progress screen appears as Windows loads.
  5. For any detected threat select which action to take unless you have previously specified automatic actions in Boot-Time Scan settings.

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. Select ProtectionVirus Scans.
  2. Click Settings (the gear icon) on the right-hand 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 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 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 to scan programs that automically start when you turn on your computer.
    6. Actions: to configure automatic responses to any threats detected by the scan, ensure Perform automatic actions during this scan is ticked, then select one of the following:
      • Fix automatically: attempts to repair the file. If unsuccessful, moves the file to the Virus Chest or deletes the file if neither action is successful.
      • Move file to Virus Chest: sends the file to the Virus Chest where the file cannot harm your system.
      • Delete: permanently removes the file from your PC.
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, the Boot-Time scan may delete the file if an automatic action is set up. Though Avast has a number of measures designed to prevent such issues, false positives may occur.
  • Avast Premium Security 19.x
  • Avast Free Antivirus 19.x
  • Avast Omni 1.x
  • Avast Premier 19.x
  • Avast Internet Security 19.x
  • Avast Pro Antivirus 19.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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