interactive.c: disable remote access to the service pipe

interactive.c: disable remote access to the service pipe

Remote access to the service pipe is not needed and might
be a potential attack vector.

For example, if an attacker manages to get credentials for
a user which is the member of "OpenVPN Administrators" group
on a victim machine, an attacker might be able to communicate
with the privileged interactive service on a victim machine
and start openvpn processes remotely.

CVE: 2024-24974

Microsoft case number: 85925

Reported-by: Vladimir Tokarev <vtokarev@microsoft.com>
Change-Id: I8739c5f127e9ca0683fcdbd099dba9896ae46277
Signed-off-by: Lev Stipakov <lev@openvpn.net>
Acked-by: Heiko Hund <heiko@openvpn.net>
Message-Id: <20240319151723.936-2-lev@openvpn.net>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg28419.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>