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Blog/Cyber Insurance/This article
Cyber InsuranceMar 29, 20267 min read

The 5 Open Ports That Will Get Your Cyber Insurance Denied

Cyber insurance underwriters run automated port scans during underwriting. These 5 open ports trigger the most denials, exclusions, and premium spikes — and 14% of SMBs have at least one of them exposed.

DG
Daniel Groves
Head of Security Research · ComplianceLayer
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Part 3 of 4Cyber Insurance for MSPs
← PreviousThe 12-Point Security Checklist Cyber Insurers Actually UseNext →Why Your SSL Certificate Passed But Your Insurance Application Failed
DG
Daniel Groves
Head of Security Research · ComplianceLayer
ComplianceLayer research team analyzing security frameworks, compliance standards, and emerging threats.
TopicsCyber InsuranceOpen PortsRDPMSPNetwork Security
On this page
  • The 5 Ports and Their Insurance Impact
  • Port 3389: RDP
  • Port 445: SMB
  • Port 23: Telnet
  • Port 21: FTP
  • Port 5900: VNC
  • How to Check Before the Underwriter Does
  • Fix Priority Order
  • The MSP Opportunity
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