Additionally to user:group, modes also need changing

tools/openbsd/attach

@@ -11,6 +11,8 @@ case $DEVCLASS in
 		echo $BUSNAME > /var/run/${DEVNAME}.bus
 		chown _cups:_saned /dev/"$DEVNAME".*
 		chown _cups:_saned /dev/"$BUSNAME"
+		chmod 660 /dev/"$DEVNAME".*
+		chown 660 /dev/"$BUSNAME"
 		;;
 	esac
 	;;

tools/openbsd/detach

@@ -10,8 +10,10 @@ case $DEVCLASS in
 		BUSNAME=$(cat /var/run/${DEVNAME}.bus)
 		rm -f /var/run/${DEVNAME}.bus
 		chgrp wheel /dev/"$DEVNAME".*
+		chmod 600 /dev/"$DEVNAME".*
 		test -n "$BUSNAME" &&
 			chown root:wheel /dev/"$BUSNAME"
+			chmod 600 /dev/"$BUSNAME"
 		;;
 	esac
 	;;