Palo Alto Networks Knowledgebase: Access for Microsoft SmartScreen Filter on IE

Access for Microsoft SmartScreen Filter on IE

Created On 02/07/19 23:38 PM - Last Updated 02/07/19 23:38 PM
URL Filtering


Microsoft Internet Explorer (IE) incorporates a feature called SmartScreen Filter to protect users from accessing malicious websites. This feature needs access to via SSL (tcp/443), and IE may encounter issues when access to the site is blocked. Symptoms include:

  • File downloading stops in the middle of download.
  • Internet Explorer may stop responding when access to the SmartScreen Filter Service is blocked [Link to Microsoft KB article].
  • Downloading a file using Internet Explorer 8 results in duplicate application launches [Link to Microsoft KB article].


Check the traffic and URL filtering logs to see if on port 443 is being blocked on the Palo Alto Networks firewall. If it is, then configure a security policy (with URL Filtering) on the Palo Alto Networks firewall to permit this traffic. Or, if the SmartScreen Filter is not necessary, then disabling the feature on IE is an alternative method to resolve the issue.

owner: yogihara

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