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PUP.Optional.AppSync is Malwarebytes' generic detection name for a family of bundlers.


Users of affected systems may notice a running process called AppSync.exe.

Type and source of infection

Users may have installed PUP.Optional.AppSync themselves not realizing it was a bundler. Bundlers bank on the names of popular programs users generally want to install onto their systems, and those who aren’t familiar with bundlers may welcome the additional free programs. Unfortunately, a majority of these are categorized as unwanted software, such as adware and browser toolbars.


block PUP.Optional.AppSync

Malwarebytes blocks PUP.Optional.AppSync


Malwarebytes can detect and remove PUP.Optional.AppSync without further user interaction.

  1. Please download Malwarebytes to your desktop.
  2. Double-click MBSetup.exe and follow the prompts to install the program.
  3. When your Malwarebytes for Windows installation completes, the program opens to the Welcome to Malwarebytes screen.
  4. Click on the Get started button.
  5. Click Scan to start a Threat Scan.
  6. Click Quarantine to remove the found threats.
  7. Reboot the system if prompted to complete the removal process.

Add an exclusion

Should users wish to keep this program and exclude it from being detected in future scans, they can add the program to the exclusions list. Here’s how to do it.

  • Open Malwarebytes for Windows.
  • Click the Detection History
  • Click the Allow List
  • To add an item to the Allow List, click Add.
  • Select the exclusion type Allow a file or folder and use the Select a folder button to select the main folder for the software that you wish to keep.
  • Repeat this for any secondary files or folder(s) that belong to the software.
If you want to allow the program to connect to the Internet, for example to fetch updates, also add an exclusion of the type Allow an application to connect to the internet and use the Browse button to select the file you wish to grant access.

Associated threats

  • PUP.Optional.AppMaster
  • PUP.Optional.AppMaster.TskLnk
  • PUP.Optional.AppSync.TskLnk

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