Author:  Ritesh Khadgaray <ritesh.khadgaray@canonical.com>
Date: Thu Oct 31 04:06:25 IST 2013

From http://www.reddit.com/r/Ubuntu/comments/1pdo5q/using_network_manager_with_1310_server/

The wpa passphrase is stored there in plain text and by default the file is 644
allowing anyone with access to the system to gain the passphrase.

Advisable to change the permissions on /etc/network/interfaces to 600


--- a/write_interface.c	2013-10-31 03:53:12.077633326 +0530
+++ b/write_interface.c	2013-10-31 03:56:24.117626770 +0530
@@ -274,6 +274,7 @@ int netcfg_write_interface(const struct
 	}
 	
 	if (rv && interface && is_wireless_iface(interface->name)) {
+		chmod(iINTERFACES_FILE, S_IRUSR|S_IWUSR);
 		di_debug("Writing wireless options for %s", interface->name);
 		rv = nc_wi_wireless_options(interface, fd);
 	}