Curing the BIND pain

Mailman List Mirror (Read Only)
1

Let's assume that BIND has a way to know when it is dangerously out of
date. The mechanism used would be up to ISC and I'll admit that it would
probably involve some sort of DNS records in an ISC-run domain because
that's the only way that has a high likelihood of working given the
number of firewalls and caching nameservers that may be between a given
BIND box and ISC. Seems to me that ISC has always maintained that there
are two version numbers, one 4.x and one 8.x, that are always the oldest
ones you can run and still be secure against known exploits. So the info
stored in the ISC DNS server really doesn't need to be more than those two
version numbers.

OK, now assume that we have a BIND server which has detected that it is
out of date and at risk of attack. What should it do?

Well, first of all, what would a human being do if if realised that it was
at risk of attack and they had no means of contacting their friends or the
police. A child might cry out and an adult might yell for help in case
someone was near enough to hear. BIND is in a similar situation. It
doesn't know if there is anyone looking after it but it is hurting, so
let's make it cry out.

I suggest that an appropriate technique would be for the BIND server to
originate traffic on it's local subnet that would look suspicious and
possibly trigger intrusion alarms. Send out some packets to the broadcast
address. Do some portscanning of all addresses on the subnet. Find any
open port 80 and retrieve a URL containing
BIND/server/at/10.7.7.1/has/security/vulnerability, find any open port 25
and send email to postmaster containing the same message, etc.

Not enough traffic to be a DoS but enough to show up in various logs in
case someone is looking at some of them.

Even then, this is still a string and sealing wax solution. It's
situations like this that demonstrate just how primitive our supposedly
high technology really is.

--Michael Dillon

2

In the immortal words of Michael.Dillon@radianz.com (Michael.Dillon@radianz.com):

I suggest that an appropriate technique would be for the BIND server to
originate traffic on it's local subnet that would look suspicious and
possibly trigger intrusion alarms.

Good lord.

I'm a little stuck for a proper analogy for this. A car that
"helpfully" starts emitting noxious smoke to let you know that it's
time for a tune-up? A refridgerator that drips bleach into your
vegetable drawers to remind you to replace the coolant? An answering
machine that replaces the outgoing message with a stream of
profanities to alert callers that the incoming message tape is full?

If people are so concerned about BIND's security that they're willing
to seriously consider implementing ideas like this, why are they not
willing to either consider replacing BIND with DNS software that is
secure by design (*cough* *cough*), or paying the ISC to produce a
properly secured BIND?

The solution to the Ford Pinto problem was not to recommend that
people duct-tape sofa cushions and homemade warning lights to the back
bumper.

-n

------------------------------------------------------------<memory@blank.org>
"Thus do `Snuff Movies' take their place with `Political-Correctness,' `Sex
Addiction,' and `Postmodernism' as Godzillas of bogus moral panic, always
threatening to crush the nation in their jaws, but never quite willing to take
the final step of biting down. (--www.suck.com)
<http://blank.org/memory/&gt;\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-

3

I suggest that an appropriate technique would be for the BIND server to
originate traffic on it's local subnet that would look suspicious and
possibly trigger intrusion alarms. Send out some packets to the broadcast
address. Do some portscanning of all addresses on the subnet. Find any
open port 80 and retrieve a URL containing
BIND/server/at/10.7.7.1/has/security/vulnerability, find any open port 25
and send email to postmaster containing the same message, etc.

Better yet, why not just have it print to console "BIND INSECURE, UPGRADE,
SHUTTING DOWN THE SERVER NOW" and then halt? Far more likely to get
noticed.

Not enough traffic to be a DoS but enough to show up in various logs in
case someone is looking at some of them.

If you have somebody looking a firewall or IDS logs, you won't need to be
told to upgrade bind. Besides, plenty of networks who do stay current on
application security would miss a little pretend DOS.

The best solutions I can come up with all revert to the undesired "stop
working" solution, in effect.

My favorite notion, which I didn't even suggest because of Paul's mandate
that the solution not involve breaking bind, would be to return, in
response to every query, the IP address of a special website that says
"THE VERSION OF BIND ON YOUR NAMESERVERS IS VULNERABLE" or whatever, and
include instructions on how to upgrade.

Sure, it will break everything except http, and flood this webserver with
a ridiculous amount of unwanted traffic (bgp anycast with filtering
everything not destined for port 80, to help stem that a little?), but at
least people will know why nothing is working, once they fire up a
browser.

Looming large, of course, is the fact that people would have to upgrade to
get any of this "security upgrade" functionality. So we'd really be only
partially solving a problem in which we won't see any benefit for years to
come, which is usually enough impetus to kill a project these days.

Andy

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Andy Dills 301-682-9972
Xecunet, Inc. www.xecu.net
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Dialup * Webhosting * E-Commerce * High-Speed Access

4

Might I suggest that you put together a group of you - four
or five should do fine, and draw up a list of all the things
that you want changed in "super BIND" or whatever you want
to call it, pass it through the group for a public airing
and then send it to the IETF's DNS WG's as a request. If you
are not getting what you need to operate your networks, then
a commitment to proactive responses requires this, or
something like it.

Tell them what you need to accomplish and not how to do it,
and they will build a protocol to satisfy this request
whether they redesign or morph BIND. It will also do wonders
for both organizations politically.

Just a thought.

Todd