The following table lists URLs and ports that should be opened on your firewall for Malwarebytes on Windows version 4 devices to communicate properly with these servers. By default, these ports are open, but if you have customized your firewall verify the following rules are in place.
| URL | Purpose |
| www.malwarebytes.com:443 | Used to verify connectivity to the Malwarebytes servers. |
| cleo.mb-internal.com:443 | Used by the in-app purchase flow to simplify the process of upgrading or renewing your Malwarebytes Premium subscription. |
| links.malwarebytes.com:443 | Used by the in-app purchase flow to simplify the process of upgrading or renewing your Malwarebytes Premium subscription. |
| iris.mwbsys.com:443 | Used for serving in-app messaging, such as news about the latest threats, personalized reports, renewal reminders or other offers. |
| my-device.malwarebytes.com:443 | Used to register your installation with Malwarebytes My Account portal, my.malwarebytes.com. |
| cdn.mwbsys.com:443 | Used to deliver new updates and downloads to the Malwarebytes product. |
| sirius.mwbsys.com:443 | Used to check for updates for both the product version and the protection database. |
| keystone.mwbsys.com:443 |
Used to validate your Malwarebytes Premium subscription. |
| telemetry.malwarebytes.com:443 |
Communicates telemetry and threat information to Malwarebytes servers. More information on our telemetry can be found on our Privacy Policy. |
| hubble.mb-cosmos.com:443 |
Used to validate threats against Malwarebytes Nebula servers for better protection and to reduce potential for detection of legitimate applications. |