Scanning your PC for viruses with Avast Antivirus

Avast Antivirus provides a range of scans to protect your PC from malware. You can also create your own scan and specify the parameters. Refer to the sections in this article for details about the following Virus Scans:

  • Smart Scan: A comprehensive scan that detects malware, out-of-date software, browser add-ons with poor reputations, network threats, and performance issues.
  • Full Virus Scan: A predefined, in-depth scan of your system that checks your storage drives and memory for malware (including rootkits).
  • Targeted Scan: Scans the folders you select when you initiate the scan.
  • Boot-Time Scan: Scans your PC during the next system startup before any malware is launched. Running a Boot-Time Scan during startup improves the chances of detecting and removing malware before it can attack your PC.
  • Custom scans: Scan your PC according to the parameters that you specified for your scan.
  • Explorer Scan: Scans specific files or folders directly from your desktop via File Explorer.

Run a scan

  1. Open Avast Antivirus and go to ProtectionVirus Scans.
  2. Run your preferred scan:
    • Smart Scan: Click the Run Smart Scan button.
    • Full Virus Scan: Click the Full Virus Scan tile.
    • Targeted Scan: Click the Targeted Scan tile, then select the file or folder you want to scan, and click OK.
    • Boot-Time Scan: Click the Boot-Time Scan tile, then click Run On Next PC Reboot.
    • Custom scans: Click the Custom scans tile, then click Scan Now on the panel for the scan you want to run.
To run Explorer Scan, right-click a file or folder on your desktop or in File Explorer, then select Scan selected items for viruses in the menu that appears.

Create a custom scan

  1. Click the Custom scans tile.
  2. Click Create A New Scan.
  3. Define the scan parameters:
    • Scan name: Type a name for your scan into the text box.

    Customize your scan

    • Scan type: Click the drop-down menu and select the type of scan you want.
    • Frequency: Click the drop-down menu and select how often your scan runs.

    Advanced settings

    • Sensitivity (Medium by default): Click and drag the slider to adjust the scan sensitivity. The higher the sensitivity, the higher the protection and potential for false positive malware detection. Lower sensitivity reduces the potential for false positive detections, but may reduce the effectiveness of the scan.
    • Scan for potentially unwanted programs (PUPs): Tick the box to enable Avast to scan for programs that are stealthily downloaded with other programs and typically perform unwanted activity.
    • Follow links during scan: Tick the box to enable Avast to scan other files used by the files being scanned for potentially harmful content.
    • Test whole files: Tick the box to enable Avast to scan entire files rather than only the parts typically affected by malicious code.
    • Scan priority: Use the drop-down menu to set your scan priority (medium priority by default).

    Scan areas

    • All Harddisks: Select to enable Avast to scan all hard drives on your PC.
    • System drive: Select to include data that is stored on physical devices such as hard drives and USB sticks.
    • All removable media: Tick to enable Avast to scan applications that launch automatically when you insert a USB or other removable device into your PC. Scanning removable media may take a long time due to speed limitations.
    • Rootkits: Tick to enable Avast to scan for hidden threats in the system.
    • CD-ROM & DVD drives: Tick to enable Avast to scan CD and DVD drives for malicious content.
    • Startup programs and modules loaded in memory: Tick to enable Avast to scan applications and processes that launch after system startup or run in the background.

    Packers and Archives

    • Scan only common installers: Select to scan only commonly used file types such as .zip, .rar, and other executable or installer archives.
    • Scan all archives: Select to scan all archive files, which significantly increases the scan duration.
    • Don't scan archives: Select to exclude all archive files from the scan.

    File Types

    • Content based types (slow): Select to scan files that are typically most vulnerable to malware attacks.
    • Name extension based types (fast): Select to only scan files with risky extensions, such as .exe, .com, .bat.
    • Scan all files (very slow): Select to scan all files on your PC for malware.

    Automatic actions

    • Perform automatic actions during this scan: Tick this option to enable it, then define the automatic action Avast will perform when an infected file is found.
      • Fix automatically: When an infected file is detected, Avast will try to fix the file. If repair is not possible, the file is moved to the Virus Chest. If this fails, the file is deleted.
      • Move file to Virus Chest: When an infected file is detected, Avast moves the file to the Virus Chest.
      • Delete file: When an infected file is detected, Avast automatically deletes the file.
    • Shut down computer after scan finishes: Tick to enable Avast to shut down your PC after your scan completes.
    • Generate report file: Tick to enable Avast to create and store a report file automatically after the scan completes.
  4. Click Save to complete your custom scan setup.

To edit your custom scan settings, go to ProtectionVirus ScansCustom scans, then hover your cursor over the scan name and click More (three dots) ▸ Settings.

Process scan results

After a scan completes, Avast displays all found issues. You can resolve the issues directly on the results screen, or configure each Virus Scan to resolve issues automatically upon detection.

Some detections may require a separate paid subscription to resolve.

Smart Scan

To learn more about resolving found issues after Smart Scan completes, refer to the following article:

Other Virus Scans

Define how each scan automatically reacts to a found issue by follow the steps below:

  1. Open Avast Antivirus and go to MenuSettings.
  2. Select ProtectionVirus Scans.
  3. Click the tab of your chosen scan.
  4. Scroll down, then tick the box next to Perform automatic actions during this scan. Then select which action you want Avast to perform when an issue is found:
    • Fix automatically: When an infected file is detected, Avast will try to fix the file. If repair is not possible, the file is moved to the Virus Chest. If this fails, the file is deleted.
    • Move file to Virus Chest: When an infected file is detected, Avast moves the file to the Virus Chest.
    • Delete file: When an infected file is detected, Avast automatically deletes the file.

If you want Avast to do nothing when an infected file is found, untick the box next to Perform automatic actions during this scan (not recommended). To manage unresolved scan detections at any time, go to ProtectionVirus ScansScan history.

Special cases

For incomplete scans, an error message indicating the reason the scan was unable to complete is visible on the scanning screen. Although there are many different reasons a scan may be unable to complete, some of the most common reasons are:

  • Archive is password protected: Indicates that the file is password protected. Some programs use password protected archives to store their data even if you did not set the password. Depending on your scan settings, only the "wrapper" file is scanned while the archive content is not.
  • Archive is corrupted: Indicates that the file may be corrupt because it was only partially downloaded or saved to your harddisk, or that it is a special type of archive.
  • The process cannot access the file because of another process: Indicates that another process or program was accessing the file during the scan.
  • The file is a decompression bomb: Indicates that the file was too large to be decompressed for malware analysis. Decompression of large files generates vast amounts of data which can cause your system to be unstable or cause it to crash.
Files that are stored in archives cannot harm your system unless they are decompressed.

Adjust scan settings

Although customizable settings are available for some Virus Scans, we recommend you only modify settings for Custom Scans. To configure scan settings:

  1. Go to ProtectionVirus Scans.
  2. Click Settings (the gear icon) in the top-right corner of the Virus Scans screen.
  3. Select the tab of your chosen scan.
  4. Configure your preferred settings.

For more information about Virus Scan settings, refer to the following article:

Create and use Rescue Disk

If you suspect your PC is infected with malware and all other Virus Scans (including the Boot-Time scan) were unable to resolve the issue, you can use Rescue Disk. Rescue Disk enables you to scan your PC when your system is not running. This method significantly increases your chances of detecting and removing malware because the malware is detected before it is able to counteract.

For more information about Rescue Disk, refer to the following article:

Review scan history

To view details of your previous scans:

  1. Go to ProtectionVirus Scans.
  2. Click Scan history.
  3. Hover your cursor over a scan panel, then click the down arrow to see the scan details.
  • Avast Omni 1.x
  • Avast Premium Security 21.x
  • Avast Free Antivirus 21.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 with Convenient Rollup Update, 32 / 64-bit

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