Who's That Knocking At My Door? Go Away!

[InfoSec News <isn () c4i org>]

http://www.computerworld.com/cwi/community/story/0,3201,NAV65-663_STO60469,00.html

By VINCE TUESDAY 
May 14, 2001 

One of the nagging problems in information security is the difficulty
of finding out how many security incidents occur. Unfortunately, this
information is difficult to obtain.

Companies fear the public relations and share-value impact of
disclosing a security breach. Perversely, revealing even an
unsuccessful attack can be a public relations disaster. And once an
organization announces that it has been attacked, it may suffer
further attacks as a result of the news coverage.

For other crimes, we can use police statistics or insurance claims
data to measure the change in risk over time. Currently, however,
there isn't much of a market for cyberinsurance, so insurance data
isn't available. Police data isn't much better because companies are
hesitant to report computer crimes. Some distrust the police,
believing them to have a low level of awareness of computer security
issues. Laws like the Freedom of Information Act and the low rate of
successful prosecutions add to this distrust.

But companies can't hide everything. The highest-profile attacks in
the current environment are Web site defacements. A useful resource in
this area is Attrition.org's Web site. Hackers notify this group when
they deface a site, and Attrition.org makes a mirror copy of it as a
record. This means it has accurate data reflecting trends in this
area. And the current trend isn't good. Attrition.org's Web site is
seeing about 30 defacements per day, an increase from 13 per day a
year ago and two per day two years ago. And it doesn't look like this
will improve anytime soon.

To supplement this data from the outside world, we also regularly
examine data from our systems to ensure that our defense is properly
focused. We have an intrusion-detection sensor outside the firewall
that logs many attacks, and we also log a great deal at our firewalls.
As an exercise, we recently analyzed a week's worth of data down to
the last packet and noticed some remarkable trends. I hadn't looked at
this data in detail for some time, and I was startled by what we
found.

My company was an early adopter of the Internet, so we have a large
address range. This means that if an attacker picks an address at
random, we have a 1 in 65,000 chance that we'll be the target. We are
a major financial organization, making us a possible target of choice
for directed attacks.

So, given all that, how many attacks and probes do you think we
detect? One per month? One per day? I thought the result would be
something in the range of once per hour. My research uncovered a much
higher figure: We detected 1.5 attacks every second.

Of the non-Web connections (such as Domain Name System, File Transfer
Protocol or e-mail), 85% were unauthorized, consisting of attempts to
gather information or compromise our systems. Our firewall or our
intrusion- detection system blocked these unauthorized connectionsno
doubt a few of them were errors caused by people mistyping IP
addresses. It's also possible that some much more competent attacks
penetrated our outer shell.

The most popular attacks are those that use scanning tools to target
known vulnerabilities. The top attacks in our sample week were DNS
BIND buffer overflow probes (379,273), Back Orifice probes (64,932),
WU-FTP buffer overflow probes (64,824) and NetBIOS share name probes
(38,285).

> From the perspective of an attacker, the DNS and FTP attacks make a
certain amount of sense. Recent high- profile, easy-to-exploit
problems have been discovered in these servers that some companies
haven't yet patched. Exploiting these problems can give the attacker
root access to critical servers.

But the next two? These include some foolish attacks by obviously
unskilled individuals. To run a scripted attack doesn't take very much
skill, but at least you're trying to break into a system on your own
behalf. Those that scan for Back Orifice and SubSeven Trojan horse
programs are bottom feeders.

These are script kiddies that are too lazy to break into systems
themselves but are looking for systems that other people have already
broken into and left back doors into. Does this ever work? Anyone with
even the most simple firewall will have blocked attacks to these
ports, and all antivirus software detects and protects against these
tools.

The volume of these probes for prebroken systems is worryingsurely,
these kids must sometimes succeed, meaning that there must be many
machines with Back Orifice or SubSeven running, leaving them open to
the least competent hackers. If someone were to try the real-world
equivalent of these four scanning attackschecking each car in a lot to
see if it is unlocked by trying every door - someone would surely
notice, and the perpetrator would almost certainly be warned off. The
brazenness and sheer mass of these attempts show that these attacks
aren't being noticed or that when they're reported, no effective
action is being taken.

This doesn't bode well for the future of the Net. More and more people
are coming online, often without sufficient security protection.
Within a second after a Web site goes online, strangers are trying to
break into the systems. Users may expect that law enforcement will
protect them from malicious strangers, but no such protection exists
at present. Indeed, once a machine has been hacked, even if users
become aware of the intrusion, they may find fumigating their machines
difficult.


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