Windows 10 must be configured to prioritize ECC Curves with longer key lengths first.

From Windows 10 Security Technical Implementation Guide

Associated with: CCI-000803

SV-89087r1_rule Windows 10 must be configured to prioritize ECC Curves with longer key lengths first.

Vulnerability discussion

Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. By default Windows uses ECC curves with shorter key lengths first. Requiring ECC curves with longer key lengths to be prioritized first helps ensure more secure algorithms are used.

Check content

If the following registry value does not exist or is not configured as specified, this is a finding. Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SOFTWARE\Policies\Microsoft\ Cryptography\Configuration\SSL\00010002\ Value Name: EccCurves Value Type: REG_MULTI_SZ Value: NistP384 NistP256

Fix text

Configure the policy value for Computer Configuration >> Administrative Templates >> Network >> SSL Configuration Settings >> "ECC Curve Order" to "Enabled" with "ECC Curve Order:" including the following in the order listed: NistP384 NistP256

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