Security through obsolescence

[InfoSec News <isn () c4i org>]

http://www.theregister.co.uk/content/55/25608.html

By Robin Miller, NewsForge.com
Posted: 06/06/2002 at 12:10 GMT

Here's an interesting way to secure an Internet-connected computer
against intruders: Make sure the operating system and software it runs
are so old that current hacking tools won't work on it. This was
suggested by Brian Aker, one of the programmers who works on
Linux.com, NewsForge, Slashdot, and other OSDN sites; he runs several
servers of his own that host a number of small non-profit sites in the
Seattle area. "I have one box still running a version of Solaris
that's so old none of the script kiddies can figure it out," Brian
says. "They tend to focus on the latest and greatest, and don't have
the slightest idea how to handle my old Sun box."

Brian points out that some of the most secure Department of Defense
Web sites -- ones that don't make headlines by getting cracked all the
time -- run old versions of Mac OS and the venerable WebSTAR server
suite. "[Mac is] a great operating system for that application," he
says. "No scripting or remote capability at all, so there's no way for
them to get in."

Not only that, the hacker/cracker crowd is fixating, as usual, on the
latest versions of everything, like Windows 2K/XP, Mac OS X, the most
recent Linux kernels and BSDs, the newest Solaris, and so on. What fun
is there in breaking into a system running something so ancient only a
dad would even consider using it? There's also an obscurity factor to
consider here, and not the one proprietary software advocates usually
trot out when discussing security issues.

True "security through obscurity"

Most Web site takedowns and system intrusions make use of known
vulnerabilities in a particular operating system or server software
package. These vulnerabilities are typically discovered, a little at a
time, by thousands of bad hackers who poke and prod at systems,
port-scanning and probing them, sharing the information they gain from
their (mostly failed) attempts with each other. A million monkeys with
Internet connections may not reproduce any Shakespeare plays -- they
need to use old-fashioned typewriters to do that -- but they sure as
bleep are going to find vulnerabilities in any host they contact
sooner or later simply by sheer weight of numbers, especially if the
operating system or software they attack is popular enough that they
have many instances of it out there to look and poke at. It doesn't
matter whether the operating system and server software under attack
is proprietary or Open Source. Sooner or later, with enough monkeys
scratching at it, every single chink or opening can be discovered and
exploited.

Imagine a custom operating system used by only a few servers, running
server software so oddball that cracking lessons learned on mainstream
servers don't apply to it at all. Or imagine running a DOS variant or
an OS like AIX that has never been widely used for Net-attached
servers but is adequate for handing out simple Web pages and receiving
responses through online forms and handling email, which are the
primary tasks performed on most publicly-accessible servers.

Now imagine your local script kiddie trying to crack a box running an
operating system and server software he's never seen before, about
which no information is available in the usual online hacker hangouts.  
Chances are, he's going to move on to an easier target.

This is security through obscurity at its finest. Even if the custom
operating system and server software are Open Source, low-level
attackers aren't going to bother poring over the code thoroughly
enough to find its vulnerabilities, and those few who have the skill
level needed almost certainly have better things to do with their time
-- like work -- and won't bother.

Really dumb stuff

Never forget, most intrusions and defacements exploit really stupid
administrator or user mistakes, like using "password" as the password
for remote access or running all kinds of unnecessary services that
create security holes so big a whale could dive through them. These
lapses have nothing to do with the operating system or software being
used. No operating system or application ever written is immune to
user stupidity. Some just take more stupidity to botch than others,
you might say. But that's enough about that. Let's go back to talking
about old operating systems.

Age before beauty

One advantage of mature software is that lots of people have already
tried to crack it and lots of patches have been written. A smart
sysadmin like Brian, running an ancient version of Solaris, has kept
up with security updates over the years and has installed all of them
he has found. What some people might sneer at as "obsolete" software,
others might call "carefully tested" or "proven." Indeed, Debian Linux
users often point to the fact that Debian's stable branch does not
include the latest kernel or software as one of its great strengths;  
Debian lets others explore the latest and greatest -- and fall victim
to the latest and greatest exploits -- before all the kinks are worked
out to the Debian maintainers' satisfaction.

Note that an awful lot of servers out there are still running on Red
Hat 6.1 or 6.2, not Red Hat 7.x, and that it takes a long time for the
latest version of Apache to trickle out into the world full-strength.  
Because these programs have zero licensing cost attached to updates,
why would so many sysadmins keep using old versions when new ones no
doubt offer more and slicker features? Obviously, those sysadmins have
the same outlook as delivery truck fleet managers who refuse to buy a
new model during its first year or two in production. They prefer to
wait until all the kinks are worked out and all the defects and
maintenance tricks have been discovered and applied by early adopters
before jumping from the tried and true into something new.

This is sane behavior for a conservative business manager whether she
is running a fleet of Web servers or a fleet of trucks -- or even a
fleet of Web servers for a trucking company. But it may be even more
sane to hold on to the same servers and trucks even when others sneer
at them as being old, even if new versions are smoother and easier to
administer or drive. Quite simply, once you have worked with a piece
of software or a truck for a number of years, you know its quirks
inside and out. When it acts up in a subtle way someone not used to it
might not even notice, long experience with it can point an observant
sysadmin or mechanic straight to a problem, thereby saving downtime
and repair costs.

Because "Total Cost of Ownership" is the big management buzz phrase
that cuts across all business areas, and anything new requires a
learning curve, sometimes it is best to just keep on using the old
whatever as long as it does its job reasonably well.

At some point -- hopefully before Microsoft stops supporting it --
Windows NT may be reasonably secure against most common exploits. If
nothing else, by that time there will be hundreds of thousands of
sysadmins who have learned how to secure it as hard as possible, even
if they had to learn some lessons the hard way -- by getting cracked.  
At the same time, the script kiddies and malicious hackers who ran
roughshod over NT servers when they first appeared have aged. Most of
them probably have jobs and responsibilities by now, and aren't
getting their kicks playing in other people's systems but are busily
securing ones they run themselves.

The next generation of bad-kid hackers probably won't mess much with
NT -- or pre-X Mac OS or Linux pre-2.5 kernels or Apache pre-2.x or
any of the other operating systems and server applications their
fathers or older siblings ran "back in the day," while those same
fathers and older siblings will have piled up endless experience
securing those old, now-obscure programs, making them harder targets
than the latest stuff.

You never read about this kind of "security through obscurity," which
can just as correctly be called "security through obsolescence."  
Despite this lack of publicity, it may be as effective a tactic as any
other, and it can be implemented without spending a dime.



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