April CRYPTO-GRAM newsletter

                  CRYPTO-GRAM

                 April 15, 2003

               by Bruce Schneier
                Founder and CTO
       Counterpane Internet Security, Inc.
            schneier@counterpane.com
          <http://www.counterpane.com>


A free monthly newsletter providing summaries, analyses, insights, and 
commentaries on computer security and cryptography.

Back issues are available at 
<http://www.counterpane.com/crypto-gram.html>.  To subscribe, visit 
<http://www.counterpane.com/crypto-gram.html> or send a blank message 
to crypto-gram-subscribe@chaparraltree.com.

Copyright (c) 2003 by Counterpane Internet Security, Inc.


** *** ***** ******* *********** *************

In this issue:
      Automated Denial-of-Service Attack Using the U.S. Post Office
      The Doghouse:  EverSeal Solutions
      Crypto-Gram Reprints
      News
      Counterpane News
      Security Notes from All Over: Baseball
      National Crime Information Center (NCIC) Database Accuracy


** *** ***** ******* *********** *************


  Automated Denial-of-Service Attack Using the U.S. Post Office


In December 2002, the notorious "spam king" Alan Ralsky gave an 
interview.  Aside from his usual comments that antagonized spam-hating 
e-mail users, he mentioned his new home in West Bloomfield, 
Michigan.  The interview was posted on Slashdot, and some enterprising 
reader found his address in some database.  Egging each other on, the 
Slashdot readership subscribed him to thousands of catalogs, mailing 
lists, information requests, etc.  The results were devastating: within 
weeks he was getting hundreds of pounds of junk mail per day and was 
unable to find his real mail amongst the deluge.

Ironic, definitely.  But more interesting is the related paper by 
security researchers Simon Byers, Avi Rubin and Dave Kormann, who have 
demonstrated how to automate this attack.

If you type the following search string into Google -- "request catalog 
name address city state zip" -- you'll get links to over 250,000 (the 
exact number varies) Web forms where you can type in your information 
and receive a catalog in the mail.  Or, if you follow where this is 
going, you can type in the information of anyone you want.  If you're a 
little bit clever with Perl (or any other scripting language), you can 
write a script that will automatically harvest the pages and fill in 
someone's information on all 250,000 forms.  You'll have to do some 
parsing of the forms, but it's not too difficult.  (There are actually 
a few more problems to solve.  For example, the search engines normally 
don't return more than 1,000 actual hits per query.)  When you're done, 
voila!  It's Slashdot's attack, fully automated and dutifully executed 
by the U.S. Postal Service.

If this were just a nasty way to harass people you don't like, it 
wouldn't be worth writing about.  What's interesting about this attack 
is that it exploits the boundary between cyberspace and the real 
world.  The reason spamming normally doesn't work with physical mail is 
that sending a piece of mail costs money, and it's just too expensive 
to bury someone's house in mail.  Subscribing someone to magazines and 
signing them up for embarrassing catalogs is an old trick, but it has 
limitations because it's physically difficult to do it on a large 
scale.  But this attack exploits the automation properties of the 
Internet, the Web availability of catalog request forms, and the paper 
world of the Post Office and catalog mailings.  All the pieces are 
required for the attack to work.

And there's no easy defense.  Companies want to make it easy for 
someone to request a catalog.  If the attacker used an anonymous 
connection to launch his attack -- one of the zillions of open wireless 
networks would be a good choice -- I don't see how he would ever get 
caught.  Even worse, it could take years for the victim to get his name 
off all of the mailing lists -- if he ever could.

Individual catalog companies can protect themselves by adding a human 
test to their sign-up form.   The idea is to add a step that a person 
can easily do, but a machine can't.  The most common technique is to 
produce a text image that OCR technology can't understand but the human 
eye can, and to require that the text be typed into the form.  These 
have been popping up on Web sites to prevent automatic registration; 
I've seen them on Yahoo and PayPal, for example.

If everyone used this sort of thing, the attack wouldn't work.  But the 
economics of the situation means that this won't happen.  The attack 
works in aggregate; each individual catalog mailer only participates to 
a small degree.  There would have to be a lot of fraud for it to be 
worth the money for a single catalog mailer to install the 
countermeasure.  (Making it illegal to send a catalog to someone who 
didn't request it could change the economics.)

Attacks like this abound.  They arise when an old physical process is 
moved onto the Internet, and is then automated in some unanticipated 
way.  They're emergent properties of the systems.  And they're going to 
become more prevalent in the years ahead.

The paper:
<http://www.avirubin.com/scripted.attacks.pdf>

The Ralsky story:
<http://www.freep.com/money/tech/mwend6_20021206.htm>
<http://www.macobserver.com/article/2002/12/06.11.shtml>


** *** ***** ******* *********** *************

        The Doghouse:  EverSeal Solutions



It's a one-time pad, which is reason enough to doghouse these 
guys.  But they have this truly beautiful quote on their "How it Works" 
page:  "Now you might think that because there are only some 72 
commonly used letters, numbers and punctuation marks, where the upper 
bit of a byte is always a '0', that the attacker's job is easier and he 
can guess some of them.  That is why we scramble your data with the DES 
encryptions before we OTP encrypt it.  The DES operation scrambles the 
data on a bit basis as well as a byte basis, leaving all number bits in 
question."

<http://www.eversealsolutions.com/pro/ever.htm>


** *** ***** ******* *********** *************

             Crypto-Gram Reprints



Crypto-Gram is currently in its sixth year of publication.  Back issues 
cover a variety of security-related topics, and can all be found on 
<http://www.counterpane.com/crypto-gram.html>.  These are a selection 
of articles that appeared in this calendar month in other years.

How to Think About Security:
<http://www.counterpane.com./crypto-gram-0204.html#1>

Is 1028 Bits Enough?
<http://www.counterpane.com./crypto-gram-0204.html#3>

Liability and Security
<http://www.counterpane.com./crypto-gram-0204.html#6>

Natural Advantages of Defense: What Military History Can Teach Network 
Security, Part 1
<http://www.counterpane.com/crypto-gram-0104.html#1>

UCITA:
<http://www.counterpane.com/crypto-gram-0004.html#TheUniformComputerInfo 
rmationTransactionsAct(UCITA)> or <http://tinyurl.com/9c42>

Cryptography: The Importance of Not Being Different:
<http://www.counterpane.com/crypto-gram-9904.html#different>

Threats Against Smart Cards:
<http://www.counterpane.com/crypto-gram-9904.html#smartcards>

Attacking Certificates with Computer Viruses:
<http://www.counterpane.com/crypto-gram-9904.html#certificates>


** *** ***** ******* *********** *************


                      News



 From a news article on the arrest of al Qaeda operational planner 
Khalid Shaikh Mohammed:  "Much of the information on Mohammed's laptop 
computer was protected by an encryption code that CIA analysts cracked 
easily, U.S. intelligence officials said.  The analysts said the code 
was surprisingly simple."  More likely is that the key was stored in 
some temporary file on the disk somewhere, or fell to a dictionary 
attack.  But maybe these guys use home-grown cryptography.
<http://www.usatoday.com/usatonline/20030313/4942670s.htm>

Someone is leaking CERT alerts before they're ready:
<http://www.wired.com/news/infostructure/0,1377,58106,00.html>
<http://news.com.com/2100-1002-993375.html>

Actual problems with anonymous computerized voting:
<http://www.frogsonice.com/skateweb/articles/crash.shtml>

Users don't trust Microsoft security, but they still trust Microsoft 
security:
<http://news.com.com/2100-1002-994878.html>

Interesting paper, "Strike and Counterstrike: The Law on Automated 
Intrusions and Striking Back."
<http://www.blackhat.com/presentations/win-usa-03/bh-win-03-karnow-notes 
.pdf> or <http://tinyurl.com/9c43>

Really interesting paper, "The Myth of Security at Canada's Airports."
<http://www.parl.gc.ca/37/2/parlbus/commbus/senate/com-e/defe-e/rep-e/re 
p05jan03-e.pdf> or <http://tinyurl.com/9c46>

The origins of that fake news story about a virus-infected printer 
being smuggled into Iraq during the First Gulf War.
<http://www.securityfocus.com/columnists/147>

Saudi terrorist sympathizers learn computer security at American 
universities.  "After studying in Texas and Indiana, al-Hussayen began 
the University of Idaho's doctoral program in computer science in 1999, 
with a specialty in computer security and intrusion techniques, 
according to the indictment."
<http://www.washingtonpost.com/wp-dyn/articles/A12758-2003Mar11.html>

Analyzing the trade-offs of security gained and freedoms lost:
<http://www.nytimes.com/2003/03/11/politics/11SECU.html>
<http://www.plastic.com/article.html;sid=03/03/12/06265215;cmt=42>

Interesting paper on how to use memory errors to attack a virtual 
computer.  The attack exploits the fact that a "time of compilation" 
check is not necessarily valid at "time of use."
<http://www.cs.princeton.edu/%7Esudhakar/papers/memerr.pdf>

There are several massive networks of compromised machines, one 
consisting of around 140,000 computers.  The machines have had bots 
placed on them; the bots establish communication with Internet Relay 
Chat (IRC) servers to receive commands.  Given that it takes hundreds 
of networked computers to take down a major Internet site in a 
denial-of-service attack, these networks could do significant damage.
<http://www.eweek.com/article2/0,3959,935790,00.asp>

New way to steal password.  A Discover credit card customer receives an 
e-mail telling him that his account is on hold due to inactivity, and 
that in order to reactivate his account, he must log in to this phony 
Web site.  The information collected includes plenty of data that would 
enable identity theft: Social Security number, mother's maiden name, 
account number, and passwords.  Similar scams have targeted PayPal and 
eBay customers.
<http://www.msnbc.com/news/884810.asp>
<http://www.computerworld.com/securitytopics/security/cybercrime/story/0 
,10801,79380,00.html> or <http://tinyurl.com/7mgh>

Survey says that two-thirds of all security breaches are the result of 
human error.  The survey seems really sloppy, but I believe the results.
<http://www.computerworld.com/careertopics/careers/training/story/0,1080 
1,79485,00.html> or <http://tinyurl.com/9c4a>
<http://www.govexec.com/dailyfed/0303/031803td2.htm>
<http://www.gcn.com/vol1_no1/daily-updates/21439-1.html>

President Bush signed an executive order allowing details of the 
Internet to be classified for security purposes.
<http://news.com.com/2100-1028-994216.html?tag=sas_email>

Interesting report on spam and how to avoid it
<http://www.cdt.org/speech/spam/030319spamreport.shtml>

A proposed bill to extend the DMCA that could potentially make 
firewalls and other security devices illegal.
<http://www.freedom-to-tinker.com/archives/000336.html>

Vendor tests of face recognition systems.  "Typically, the watch list 
task is more difficult than the identification or verification tasks 
alone. Figure 8 shows detection and identification rates for varying 
watch list sizes at a false alarm rate of 1%. For the best system using 
a watch list of 25 people, the detection and identification rate is 
77%. Increasing the size watch list to 3,000 people, decreases the 
detection and identification rate to 56%."
<http://www.frvt.org/FRVT2002/documents.htm>

Risks of wiretapping today:
<http://www.businessweek.com/technology/content/feb2003/tc20030227_1190_ 
tc073.htm> or <http://tinyurl.com/9c4e>

New security flag for IPv4.  This has profound implications for 
Internet security, and is likely to be deployed world-wide within months.
<http://www.rfc-editor.org/rfc/rfc3514.txt>
<http://www.research.att.com/~smb/3514.html>

A nice article that captures the spirit of the Computers, Freedom, and 
Privacy conference in New York earlier this month:
<http://www.sfgate.com/cgi-bin/article.cgi?file=/gate/archive/2003/04/10 
/cfp.DTL> or <http://tinyurl.com/9c4l>

Man sent to jail for selling mod chips for the Xbox
<http://www.theregister.co.uk/content/54/30165.html>

Bag matching and U.S. airlines: why isn't it happening?
<http://www.businessweek.com/technology/content/apr2003/tc20030410_0829_ 
tc073.htm> or <http://tinyurl.com/9c4n>

Richard Clarke no longer works for the Bush Administration, so he can 
speak his mind about cybersecurity in the U.S. government.
<http://www.computerworld.com/governmenttopics/government/policy/story/0 
,10801,80183,00.html?nas=SEC-80183> or <http://tinyurl.com/9c4q>


** *** ***** ******* *********** *************

                Counterpane News



Bruce Schneier gave the keynote address at the Computers, Freedom, and 
Privacy conference in New York (in April).  You can listen to it here:
<http://www.cmcgc.com/CFP_2003/mp3/230401-010.mp3>

Schneier is speaking at the RSA Conference in San Francisco.  He is 
speaking on "Security Proxies and Agenda" on Wednesday, April 16, at 
9:00 AM and on "How to Think About Security" on Thursday, April 17, at 
10:00 AM.  He is also chairing the Cryptographer's Panel on April 14.
<http://www.rsaconference.net/rsa2003/>


** *** ***** ******* *********** *************

     Security Notes from All Over: Baseball



A couple of weeks ago I was listening to a baseball game on the 
radio.  The announcer was talking about the new antiterrorism security 
countermeasures at the ballpark.  One of them, he said, was that people 
are not allowed to bring bottles and cans into the park with them.

This is, of course, ridiculous.  The prohibition against bringing 
outside drinks into the park has nothing to do with terrorism.  The 
park wants people to buy drinks from their concession stands, at 
inflated prices, and to not be able to undercut those prices by 
bringing in drinks from outside.

This is an example of a non-security agenda co-opting a security 
countermeasure, and it happens a lot.  Airlines were in favor of the 
photo ID requirement not because of some vague threat of terrorism, but 
because it killed the practice of reselling nonrefundable 
tickets.  Hotels make a copy of your driver's license not because of 
security, but because they want your information for their marketing 
database.

Security decisions are always about more than security.  When trying to 
evaluate a particular decision, always pay attention to the 
non-security agendas of the people involved.


** *** ***** ******* *********** *************

   National Crime Information Center (NCIC) Database Accuracy



Last month the U.S. Justice Department administratively discharged the 
FBI of its statutory duty to ensure the accuracy and completeness of 
the National Crime Information Center (NCIC) database.  This database 
is enormous.  It contains over 39 million criminal records.  It 
contains information on wanted persons, missing persons, and gang 
members, as well as information about stolen cars, boats, and other 
information.  Over 80,000 law enforcement agencies have access to this 
database.  On average, there are 2.8 million transactions processed 
each day.

The Privacy Act of 1974 requires the FBI to make reasonable efforts to 
ensure the accuracy and completeness of the records in this 
database.  Last month, the Justice Department exempted the system from 
the law's accuracy requirements.

This isn't just bad social practice, it's bad security.  A database 
with more errors is much less useful than a database with more errors, 
and an error-filled security database is much more likely to target 
innocents than it is to let the guilty go free.

To see this, let's walk through an example.  Assume a simple database 
-- name and a single code indicating "innocent" or "guilty."  When a 
policeman encounters someone, he looks that person up in the database, 
and then arrests him if the database says "guilty."

Example 1:  Assume the database is 100% accurate.  If that is the case, 
there won't be any false arrests because of bad data.  It works perfectly.

Example 2: Assume a 0.0001% error rate: one error in a million.  (An 
error is defined as a person having an "innocent" code when he is 
guilty, or a "guilty" code when he is innocent.)  Furthermore, assume 
that one in 10,000 people are guilty.  In this case, for every 100 
guilty people the database correctly identifies it will mistakenly 
identify one innocent person as guilty (because of an error).  And the 
number of guilty people erroneously listed as innocent is tiny: one in 
a million.

Example 3:  Assume a 1% error rate -- one in a hundred -- and the same 
one in 10,000 ratio of guilty people.  The results are very 
different.  For every 100 guilty people the database correctly 
identifies, it will mistakenly identify 10,000 innocent people as 
guilty.  The number of guilty people erroneously listed as innocent is 
larger, but still very small: one in 100.

The differences between examples 2 and 3 are striking.  In example 2, 
one person is erroneously arrested for every 100 people correctly 
arrested.  In example 3, one person is correctly arrested for every 100 
people erroneously arrested.  The increase in error rate makes the 
database all but useless as a system for figuring out how to 
arrest.  And this is despite the fact that, in both cases, almost no 
guilty people get away because of a database error.

The reason for this phenomenon is that the number of guilty people is a 
very small percentage of the population.  If one in ten people were 
guilty, then a 0.0001% error rate would mistakenly arrest one innocent 
for every 100,000 guilty, and a 1% error rate would arrest 
approximately one innocent for every guilty.  And if the number of 
guilty people is even less than one in ten thousand, then the problem 
of arresting innocents magnifies even more as the database has more errors.

Now this is a simple example, and the NCIC database has far more 
complex data and tries to make more complex correlations.  And I am 
assuming that the error rate for false positives are the same as the 
error rate for false negatives, and there aren't any data dependencies 
that complicate the analysis.  But even with these complications, the 
problems are still the same.  Because there are so few terrorists (for 
example) amongst the general population, a error-filled database is far 
more likely to identify innocent people as terrorists than it is to 
catch actual terrorists.

This kind of thing is already happening.  There are 13 million people 
on the FBI's terrorist watch list.  That's ridiculous, it's simply 
inconceivable that a number of people equal to 4.5% of the population 
of the United States are terrorists.  There are far more innocents on 
that list than there are guilty people not on that list.  And these 
innocents are regularly harassed by police trying to do their job.  And 
in any case, any watch list with 13 million people is basically 
useless.  How many resources can anyone afford to spend watching about 
one-twentieth of the population, anyway?

That 13-million-person list feels a whole like CYA on the part of the 
FBI.  Adding someone to the list probably has no cost and, in fact, may 
be one criterion for how your performance is evaluated at the 
FBI.  Removing someone from the list probably takes considerable 
courage, since someone is going to have to take the fall when "the 
warnings were ignored" and "they failed to connect the dots."  Best to 
leave that risky stuff to other people, and to keep innocent people on 
the list forever.

Many argue that this kind of thing is bad social policy.  I argue that 
it is bad security as well.


What you can do: sign this petition online.
<http://www.petitiononline.com/ncic/petition.html>

News articles:
<http://abcnews.go.com/wire/Politics/ap20030324_2121.html>
<http://news.yahoo.com/news?tmpl=story2&cid=542&u=/ap/20030325/ap_on_go_ 
ca_st_pe/fbi_database_4&printer=1> or <http://tinyurl.com/86bm>

13 million people on terrorist watch list:
<http://www.nydailynews.com/04-08-2003/news/wn_report/story/73628p-68132 
c.html> or <http://tinyurl.com/9c4t>

What happens to innocents on the government's "no fly" list:
<http://www.wired.com/news/privacy/0,1848,58386,00.html>
<http://www.salon.com/tech/feature/2003/04/10/capps/index_np.html>

General risks of large law-enforcement databases:
<http://www.securityfocus.com/news/3482>
<http://www.siliconvalley.com/mld/siliconvalley/5571471.htm>


** *** ***** ******* *********** *************


CRYPTO-GRAM is a free monthly newsletter providing summaries, analyses, 
insights, and commentaries on computer security and cryptography.  Back 
issues are available on <http://www.counterpane.com/crypto-gram.html>.

To subscribe, visit <http://www.counterpane.com/crypto-gram.html> or 
send a blank message to crypto-gram-subscribe@chaparraltree.com.  To 
unsubscribe, visit <http://www.counterpane.com/unsubform.html>.

Please feel free to forward CRYPTO-GRAM to colleagues and friends who 
will find it valuable.  Permission is granted to reprint CRYPTO-GRAM, 
as long as it is reprinted in its entirety.

CRYPTO-GRAM is written by Bruce Schneier.  Schneier is founder and CTO 
of Counterpane Internet Security Inc., the author of "Secrets and Lies" 
and "Applied Cryptography," and an inventor of the Blowfish, Twofish, 
and Yarrow algorithms.  He is a member of the Advisory Board of the 
Electronic Privacy Information Center (EPIC).  He is a frequent writer 
and lecturer on computer security and cryptography.

Counterpane Internet Security, Inc. is the world leader in Managed 
Security Monitoring.  Counterpane's expert security analysts protect 
networks for Fortune 1000 companies world-wide.

<http://www.counterpane.com/>

Copyright (c) 2003 by Counterpane Internet Security, Inc.