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Short bio

PUM.Optional.FireFoxSearchOverride is Malwarebytes’ detection name for several potentially unwanted modifications (PUMs)on user.js, a Firefox browser configuration file, where the installation of any third-party add-on or extension to Firefox is allowed.

System modifications

The following string is modified in user.js:From:user_pref("extensions.autoDisableScopes", 15);To:user_pref("extensions.autoDisableScopes", 14);oruser_pref("extensions.autoDisableScopes", 0);


Malwarebytes automatically deletes the user.jsfile that triggers the detection of PUM.Optional.FireFoxSearchOverride. Also, we advise users to do a full system scan as PUM.Optional.FireFoxSearchOverride could have been added to the system by malwareor PUP.

Add an exclusion

When a Potentially Unwanted Modification (PUM)is detected on your computer, Malwarebytes for Windowsdoes not know whether it was authorized. Optimization software, malware, and Potentially Unwanted Programs (PUPs) are known to make these types of changes, hence they are regarded as potentially unwanted by design.To have Malwarebytes for Windowsignore a PUM, you must add the PUM to the Allow list. Here’s how to do it.

  1. When a PUM appears in the list of Scan results.
  2. Uncheck the entry or entries related to the PUM.
  3. Then click on Next.
  4. You will see a prompt giving you several options.
  5. Choosing Always ignore will add the PUM to the Allow List.
  6. You can remove them there when you decide they should no longer be ignored.
  7. When the PUM is on the Allow list it will no longer show up in your Scan results.