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Short bio

PUP.Optional.ForcedInstalledExtensionFF is a generic detection for a large family of browser extensions that target Firefox.


PUP.Optional.ForcedInstalledExtensionFF downloads additional code from a location hardcoded in the extensions’ javascript. Using this method these extensions can behave as coin-miners, search hijackers, or any other type of extension.

Type and source of infection

PUP.Optional.ForcedInstalledExtensionFF are forced on the user by making it as difficult as possible to leave the site without installing the extension.


block dictionaryext.xys

Malwarebytes blocks dictionaryext.xys


Malwarebytes can detect and remove PUP.Optional.ForcedInstalledExtensionFF 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.

Malwarebytes log

An example of how a removal log for PUP.Optional.ForcedInstalledExtensionFF would look:

-Log Details-
Scan Date: 2/7/18
Scan Time: 9:04 AM
Log File: 94567eaa-0bdd-11e8-9439-080027750297.json
Administrator: Yes

-Software Information-
Components Version: 1.0.262
Update Package Version: 1.0.3887
License: Premium

-System Information-
OS: Windows 7 Service Pack 1
CPU: x64
File System: NTFS
User: {computername}\{username}

-Scan Summary-
Scan Type: Threat Scan
Result: Completed
Objects Scanned: 241624
Threats Detected: 1
Threats Quarantined: 1
Time Elapsed: 4 min, 40 sec

-Scan Options-
Memory: Enabled
Startup: Enabled
Filesystem: Enabled
Archives: Enabled
Rootkits: Disabled
Heuristics: Enabled
PUP: Detect
PUM: Detect

-Scan Details-
Process: 0
(No malicious items detected)

Module: 0
(No malicious items detected)

Registry Key: 0
(No malicious items detected)

Registry Value: 0
(No malicious items detected)

Registry Data: 0
(No malicious items detected)

Data Stream: 0
(No malicious items detected)

Folder: 0
(No malicious items detected)

File: 1
PUP.Optional.ForcedInstalledExtensionFF, C:\USERS\{username}\APPDATA\ROAMING\MOZILLA\FIREFOX\PROFILES\{profile}.default\{F4262989-6DE0-4604-918F-663B85FAD605}.XPI, Quarantined, [4633], [486396],1.0.3887

Physical Sector: 0
(No malicious items detected)


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.