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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-74413	WN10-CC-000052	SV-89087r2_rule		Medium

Description
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.

STIG	Date
Windows 10 Security Technical Implementation Guide	2020-06-15

Details

Check Text ( C-94089r1_chk )
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 (F-80955r1_fix)
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