18.9.59.3.3.1 Ensure 'Do not allow COM port redirection' is set to 'Enabled'

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Information

This policy setting specifies whether to prevent the redirection of data to client COM ports from the remote computer in a Remote Desktop Services session.

The recommended state for this setting is: Enabled.

Rationale:

In a more security-sensitive environment, it is desirable to reduce the possible attack surface. The need for COM port redirection within a Remote Desktop session is very rare, so makes sense to reduce the number of unexpected avenues for data exfiltration and/or malicious code transfer.

Solution

To establish the recommended configuration via GP, set the following UI path to Enabled:

Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Device and Resource Redirection\Do not allow COM port redirection

Note: This Group Policy path is provided by the Group Policy template TerminalServer.admx/adml that is included with all versions of the Microsoft Windows Administrative Templates.

Impact:

Users in a Remote Desktop Services session will not be able to redirect server data to local (client) COM ports.

Default Value:

Disabled. (Remote Desktop Services allows COM port redirection.)

References:

CCE-37696-2

See Also

https://workbench.cisecurity.org/files/2742