Information
Windows Update must not obtain updates from other PCs on the internet.
GROUP ID: V-220835RULE ID: SV-220835r991589
Windows 10 allows Windows Update to obtain updates from additional sources instead of Microsoft. In addition to Microsoft, updates can be obtained from and sent to PCs on the local network as well as on the internet. This is part of the Windows Update trusted process; however, to minimize outside exposure, obtaining updates from or sending to systems on the internet must be prevented.
Solution
Configure the policy value for
Computer Configuration >> Administrative Templates >> Windows Components >> Delivery Optimization >> 'Download Mode'
to 'Enabled' with any option except 'Internet' selected.
Acceptable selections include:Bypass (100)Group (2)HTTP only (0)LAN (1)Simple (99)
v1507 (LTSB) does not include this group policy setting locally. For domain-joined systems, configure through domain group policy as 'HTTP only (0)' or 'Lan (1)'.
For standalone or nondomain-joined systems, configure using Settings >> Update & Security >> Windows Update >> Advanced Options >> 'Choose how updates are delivered' with either 'Off' or 'PCs on my local network' selected.