Windows Server 2019 File Explorer shell protocol must run in protected mode.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-205872	SRG-OS-000480-GPOS-00227	WN19-CC-000330	SV-205872r991589_rule	2025-02-25	3

Description
The shell protocol will limit the set of folders that applications can open when run in protected mode. Restricting files an application can open to a limited set of folders increases the security of Windows.

ℹ️ Check
The default behavior is for shell protected mode to be turned on for File Explorer. If the registry value name below does not exist, this is not a finding. If it exists and is configured with a value of "0", this is not a finding. If it exists and is configured with a value of "1", this is a finding. Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\ Value Name: PreXPSP2ShellProtocolBehavior Value Type: REG_DWORD Value: 0x00000000 (0) (or if the Value Name does not exist)

ℹ️ Check

The default behavior is for shell protected mode to be turned on for File Explorer. If the registry value name below does not exist, this is not a finding. If it exists and is configured with a value of "0", this is not a finding. If it exists and is configured with a value of "1", this is a finding. Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\ Value Name: PreXPSP2ShellProtocolBehavior Value Type: REG_DWORD Value: 0x00000000 (0) (or if the Value Name does not exist)

✔️ Fix
The default behavior is for shell protected mode to be turned on for File Explorer. If this needs to be corrected, configure the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> File Explorer >> "Turn off shell protocol protected mode" to "Not Configured" or "Disabled".