Windows 10 must not have portproxy enabled or in use.

STIG ID: WN10-00-000395  |  SRG: SRG-OS-000480-GPOS-00227 |  Severity: medium |  CCI: CCI-000381 |  Vulnerability Id: V-257593 | 

Vulnerability Discussion

Having portproxy enabled or configured in Windows 10 could allow a man-in-the-middle attack.

Check

Check the registry key for existence of proxied ports:
HKLM\SYSTEM\CurrentControlSet\Services\PortProxy\.

If the key contains v4tov4\tcp\ or is populated v4tov4\tcp\, this is a finding.

Run "netsh interface portproxy show all".

If the command displays any results, this is a finding.

Fix

Contact the Administrator to run "netsh interface portproxy delete" with elevation. Remove any enabled portproxies that may be configured.