CRYPTO-GRAM

                 July 15, 2000

               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.  To subscribe or 
unsubscribe, see below.


Copyright (c) 2000 by Counterpane Internet Security, Inc.


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In this issue:
      Full Disclosure and the CIA
      Counterpane Internet Security News
      More Counterpane Internet Security News
      News
      Even the President Can't Choose a Good Password
      The Doghouse:  Intuit QuickBooks
      Full Disclosure and Lockmaking
      Security Risks of Unicode
      Crypto-Gram Reprints
      Comments from Readers


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           Full Disclosure and the CIA



On its Web site, the New York Times published a previously classified 1954 
CIA document about the overthrow of the Iranian government.  I'm not sure 
how the New York Times got its hands on the document, but the newspaper 
decided to redact the names of Iranian citizens involved in the plot.

The document was a scanned PDF file.  What the Times did was to create an 
overlay on the pages, and drew black boxes over the names they wanted to 
obscure.  The result was a file that still had the original digital 
information, but contained extra commands to obscure that 
information.  Predictably, someone reverse-engineered the original names 
(it was suprisingly easy) and posted the restored document.  The Times 
panicked and removed the original document, but it's too late; copies are 
available on various sites worldwide.

Reactions to this have been bizarre, and almost uniformly missing the 
point.  Here's one, by William Hugh Murray: "Protecting the identity of 
intelligence sources is one of the few legitimate reasons for government 
secrecy.  A 'freedom of information activist' does not serve his own cause, 
much less our national interest, by such reckless behavior."  Ignoring 
Murray's hubris in claiming to know someone's motivations more strongly 
than he, what does this case have to do with government secrecy?  It was 
the New York Times that decided to redact the document, not the CIA.  The 
people who gave us the Pentagon Papers decided, on their own, not to 
release information that the CIA released to them.  This is very different 
than the government trying to keep secrets.  The last time I checked, the 
Times is not part of the intelligence community.

John Young, the activist Murray slams, makes classic full-disclosure 
arguments.  The information was been published by the New York Times.  Even 
though it took some work to extract, people are extracting it.  Given this 
truth, it is better to release the information so that everyone can have 
access to it -- not only those random few who reverse-engineered the PDF 
file.  Young said "Those folks who are named have a stake in knowing about it."

The opposing side has an equally predictable reaction: The information 
should be kept secret.  Just because the New York Times erred and made the 
information available to a few people doesn't mean that we should compound 
the error and make the information available to everyone.

It's a complicated question, made even more muddy by the New York Times's 
decision to redact the document.  If the CIA gave the New York Times the 
document in unredacted form, why did the Times decide to limit the public's 
knowledge of this information?

To me, this is a classic example of the power of full disclosure.  The 
information in question -- the names of the Iranian citizens -- has been 
released to the public.  Initially, it was known by only those few who had 
the means to reverse-engineer the PDF file, and those who learned as the 
information spread.  Left to its own devices, this information would spread 
slowly.  Maybe someone who wants to do these people harm would learn about 
this information; he certainly already knows that this information 
exists.  Maybe some of the people named would learn that they are named, 
and be able to take appropriate action.  But this process is slow and 
haphazard.

Better is to release the information to everyone, quickly.  This limits the 
damage that can be done.  The people named are more likely to find out they 
are named, and they are more likely to find out about it quickly.  Those 
who want to take advantage of the relative secrecy of the information 
cannot.  Everyone knows, and this levels the playing field.  It is the 
situation where only a few random people know, and others find out 
piecemeal, that is unstable and dangerous.

News articles:
<http://www.wired.com/news/politics/0,1283,37205,00.html>
<http://www.securityfocus.com/news/51>

The document:
<http://cryptome.org/cia-iran-all.htm>

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       Counterpane Internet Security News



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Looking at computer security as a risk management tool, there are many more 
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 From the beginning, I have maintained that Counterpane Internet Security 
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Quick Summary:
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Press Release:
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Q&A:
<http://www.counterpane.com/pr-lloydsqa.html>

White Paper describing the insurance offering and its context:
<http://www.counterpane.com/pr-lloydswp.html>

Press Coverage:
<http://news.cnet.com/news//0-1005-200-2232221.html?tag=st.cn.sr.ne.1>
<http://www.internetwk.com/story/INW20000710S0001>
<http://www.computerworld.com/cwi/story/0,1199,NAV47_STO46992,00.html?am>
<http://www.zdnet.com/zdnn/stories/news/0,4586,2600511,00.html>
<http://www.crn.com/dailies/digest/dailyarchives.asp?ArticleID=18243>
<http://slashdot.org/articles/00/07/10/139201.shtml>

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     More Counterpane Internet Security News



More information on Counterpane's Managed Security Monitoring service can 
be found at:
<http://www.counterpane.com/oursol.html>
<http://www.counterpane.com/coverage.html>

Bruce Schneier is speaking at BlackHat (July 26) and DefCon (July 29) in 
Las Vegas.
<http://www.blackhat.com>
<http://www.defcon.org>

Bruce Schneier will address the Digital Commerce Society of Boston on August 1.

At WebDefense, in Washington DC (Aug 9), Bruce Schneier will give a talk 
entitled "What Level of Security Can We Reasonably Expect?"
<http://www.acius.net/webd_overview.html>

For the full Counterpane conference schedule, see:
<http://www.counterpane.com/conf.html>


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                      News



Another interesting article on writing computer viruses:
<http://www.hackernews.com/bufferoverflow/99/nitmar/nitmar1.html>

Software (children's software, no less) that automatically spies on you:
<http://www.salon.com/tech/col/garf/2000/06/15/brodcast/>

The need for security.  Good article.
<http://www.acm.org/crossroads/columns/onpatrol/june2000.html>

Problems with public-key infrastructures.  This article was written well 
before I started thinking about the problems:
<http://world.std.com/~dtd/compliance/compliance.ps>

Countries are conducting military reconnaissance on U.S. computer networks:
<http://www.zdnet.com/zdtv/cybercrime/hackingandsecurity/story/0,9955,259057 
7,00.html>

Provocative articles on the risks of the new digital signature law:
<http://www.pfir.org/statements/2000-06-17>
<http://www.securityfocus.com/templates/article.html?id=50>

Interesting cryptography story.  A political party in Mexico wants an 
encryption key broken, because it believes that the resulting plaintext 
will embarrass the ruling party.
<http://www.theregister.co.uk/content/1/11508.html>
<http://www.wired.com/news/politics/0,1283,37337,00.html>

Commentary on the hype surrounding computer-security press coverage.
<http://www.computerworld.com/cwi/story/frame/0,1213,NAV47-68_STO46049,00.html>
I don't agree: I think that the current media hype will desensitize people 
to the real threats and the real risks.

NATO releases a virus.  (There's enough odd in this story for me to doubt 
its veracity, but who knows.)
<http://www.the-times.co.uk/news/pages/sti/2000/06/18/stinwenws01024.html>

The motives and psychology of the black-hat community.  Another good essay 
by Lance Spitzner.
<http://www.securityfocus.com/focus/ids/articles/kye/motives.html?&_ref=3948 
32126>

Publius is a system for anonymous, censorship-resistant publishing on the Web.
<http://cs.nyu.edu/waldman/publius/>
<http://www.washingtonpost.com/wp-dyn/articles/A21689-2000Jun29.html>
They're looking for people willing to host a Publius server.

The Secret Service is developing a Electronic Crimes Special Agent
Program.  Agents analyze new security products and alert vendors to
weaknesses.
<http://www.fcw.com/fcw/articles/2000/0626/web-secret-06-27-00.asp>

Failing dot-coms are selling private information:
<http://news.cnet.com/news/0-1007-200-2176430.html>
More proof that they should never be allowed to collect it in the first 
place, and that posted privacy policies aren't worth the phosphors they're 
displayed on.

The Sega Dreamcast copy-protection scheme has been cracked.  Is anyone 
surprised?
<http://www.mhzgaming.com/articles/dc629.htm>
<http://news.cnet.com/news/0-1005-200-2181596.html>

Special news report on Echelon:
<http://www.zdnet.co.uk/news/specials/2000/06/echelon/>
The government of France is investigating:
<http://dailynews.yahoo.com/h/nm/20000704/ts/france_usa_dc_1.html>
<http://news6.thdo.bbc.co.uk/hi/english/world/europe/newsid%5F819000/819210. 
stm>

Interesting article on the lack of security in Australian government Web sites:
<http://www.theregister.co.uk/content/1/11686.html>
And other articles on the same topic:
<http://www.it.fairfax.com.au/breaking/20000630/A43356-2000Jun30.html>
<http://www.afr.com.au/news/20000701/A44576-2000Jun30.html>

There were rumors of hackers disrupting the Space Shuttle a few years 
ago.  Here is what seems to be a coherent story:
<http://news.excite.com/news/ap/000702/20/news-britain-hacker>
NASA denies it:
<http://news.excite.com/news/ap/000703/19/nasa-hacker>
The question to ask is: why in the world are these critical systems 
attached to public networks in the first place?

Electronic Commerce: Who Carries the Risk of Fraud?
<http://www.fipr.org/WhoCarriesRiskOfFraud.htm>

NIST has published an index of computer vulnerabilities.  Called ICAT, it 
links users into a variety of publicly available vulnerability databases 
and patch sites.  ICAT is not itself a vulnerability database, but instead 
a searchable index leading one to vulnerability resources and patch 
information.  ICAT allows one to search at a fine granularity, a feature 
unavailable with most vulnerability databases, by characterizing each 
vulnerability by over 40 attributes (including software name and version 
number).  ICAT indexes the information available in CERT advisories, ISS 
X-Force, Security Focus, NT Bugtraq, Bugtraq, and a variety of vendor 
security and patch bulletins.  ICAT uses the CVE vulnerability naming standard.
<http://csrc.nist.gov/icat>

The insecurity of wireless computing:
<http://www.msnbc.com/news/429748.asp?cp1=1>

New technology for recovering erased data on electronic media:
<http://www.sciencenews.org/20000708/fob1.asp>

Good editorial.  The biggest problem in computer security is the user, not 
the computer.
<http://www.osopinion.com/Opinions/DanielHiggs/DanielHiggs1.html>

Lots of "pay-to-surf" sites are springing up, paying users to look at web 
advertisements, along with a cottage industry of programs that help rogue 
surfers bypass the rules and get paid anyway.
<http://www.wired.com/news/culture/0,1284,37329,00.html?tw=wn20000710>

Social Security numbers of the rich and famous:
<http://news.cnet.com/news/0-1005-200-340248.html>

Internet voting is unsafe (no surprise), says a new study.
News article:
<http://www.wired.com/news/politics/0,1283,37504,00.html>
Actual study:
<http://www.voting-integrity.org/text/2000/internetsafe.shtml>

Spam with huge media attachments.  Anyone care to ponder the implications 
for virus writers?
<http://adage.com/interactive/articles/20000710/article2.html>

"The Carnivore," from the FBI.  An expert system that seaches through email.
<http://www.zdnet.com/zdnn/stories/news/0,4586,2601502,00.html>
The ACLU complains:
<http://www.wired.com/news/politics/0,1283,37470,00.html>

The Cyber Group Network Corp claims tob have a technology that allows you 
to locate a stolen computer, remotely retrieve information from it, and the 
destroy it.  Sounds a bit far fetched.  But they take "security by 
obscurity to new heights:  "According to Nish Kapoor, a spokesperson for 
The Cyber Group Network, the patent pending technology that makes all this 
possible is being manufactured and developed at a remote, top-secret 
location identified only as 'Area 74.'"  Wow.
<http://www.newsbytes.com/pubNews/00/151921.html>

And even worse, software that allows companies to track down (and 
presumably prosecute) those who say unkind things about them on the 
Internet.  What happened to free speech on the Internet?
<http://www.businessweek.com/bwdaily/dnflash/july2000/nf00707g.htm>


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   Even the President Can't Choose a Good Password



According to a story regarding Clinton signing the e-signature bill with a 
smart card:

"With a magnetic card and his dog Buddy's name as a password, President 
Clinton e-signed a bill Friday that will make electronic signatures as real 
as those on paper."

Note his choice of password.  It's five characters, all alphas, and 
probably all lower case.  At least he doesn't keep it on a Post-it in his desk.

<http://www.foxnews.com:80/elections/063000/clinton_ebill.sml>


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        The Doghouse:  Intuit QuickBooks



Intuit's QuickBooks is a finance manager for small companies.  It has lots 
of great features and is one of the most popular financial packages 
available.  Unfortunately, the security sucks.

The earliest versions of QuickBooks stored usernames and passwords in the 
clear.  As the version number increased, so did the amount of obfuscation: 
first they XORed the data with a constant mask, then they added some byte 
rotations and more bit twiddling.  The latest versions of QuickBooks use 
DES to encrypt blocks of data containing a username and the corresponding 
password.  This could have made the system much harder to break, if only 
the decryption keys weren't stored in the file.

To verify that the user has the correct password, QuickBooks looks up the 
decryption key, decrypts the block, and compares the password the user 
typed in to the one it just decrypted.  Nothing prevents an unauthorized 
program from performing the same steps and printing out all the usernames 
and passwords.


Thanks to Mike Stay for pointing this out.


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         Full Disclosure and Lockmaking



"In respect to lock-making, there can scarcely be such a thing as 
dishonesty of intention: the inventor produces a lock which he honestly 
thinks will possess such and such qualities; and he declares his belief to 
the world.  If others differ from him in opinion concerning those 
qualities, it is open to them to say so; and the discussion, truthfully 
conducted, must lead to public advantage: the discussion stimulates 
curiosity, and curiosity stimulates invention.  Nothing but a partial and 
limited view of the question could lead to the opinion that harm can 
result: if there be harm, it will be much more than counterbalanced by good."

-- Charles Tomlinson's Rudimentary Treatise on the Construction of Locks, 
published around 1850.


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              Crypto-Gram Reprints



Those of you who have subscribed recently might have missed these essays 
from back issues.

Declassifying SKIPJACK:
<http://www.counterpane.com/crypto-gram-9807.html#skip>

The Future of Crypto-Hacking:
<http://www.counterpane.com/crypto-gram-9907.html#hacking>

Bungled SSL:
<http://www.counterpane.com/crypto-gram-9907.html#doghouse>


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            Security Risks of Unicode



Unicode is an international character set.  Like ASCII, it provides a 
standard correspondence between the binary numbers that computers 
understand and the letters, digits, and punctuation that people 
understand.  But unlike ASCII, it seeks to provide a code for every 
character in every language in the world.  To do this requires more than 
256 characters, the 8-bit ASCII character set; default Unicode uses 16-bit 
characters, and there are rules to extend even that.

I don't know if anyone has considered the security implications of this.

Remember all those input validation attacks that were based on replacing 
characters with alternate representations, or that explored alternative 
delimiters?  For example, there was a hole in the IRIX Web server: if you 
could replace spaces with tabs you could fool the parser, and you could use 
hexadecimal escapes, strange quoting, and nulls to defeat input validation.

The Unicode specification includes all sorts of complicated new escape 
sequences.  They have things called UTF-8 and UTF-16, which allow several 
possible representations of various character codes, several different 
places where control-characters pop through, a scheme for placing 
diacriticals and accents in separated characters (looking very much like an 
escape), and hundreds of brand new punctuation characters and otherwise 
nonalphabetic characters.

The philosophy behind the Unicode spec is to provide all possible useful 
characters for applications that are 8- or 16-bit clean.  This is 
admirable, but it is nearly impossible to filter a Unicode character stream 
to decide what is "safe" in some application and what is not.

What happens when:

- We start attaching semantics to the new characters as delimiters, white 
space, etc?  With thousands of characters and new characters being added 
all the time, it will be extremely difficult to categorize all the possible 
characters consistently, and where there is inconsistency, there tends to 
be security holes.

- Somebody uses "modifier" characters in an unexpected way?

- Somebody uses UTF-8 or UTF-16 to encode a conventional character in a 
novel way to bypass validation checks?

With the ASCII character set, we could carefully study a small selection of 
characters, categorize them clearly, and make relatively straightforward 
decisions about the nature of each character.  And even here, there have 
been mistakes (forgetting about tabs, multicharacter control-sequence 
snafus, etc).  Still, a careful designer can figure out a safe way to deal 
with any possible character that can come off an untrusted wire by 
elimination if necessary.

With Unicode, we probably won't be able to get a consistent definition of 
what to accept, what is a delimiter under what circumstance, or how to 
handle arbitrary streams safely.  It's just a matter of time before simple 
validators pass data and upper layer software, trying to be helpful, attach 
magic-character semantics, and we have a brand-new variety of security holes.

Unicode is just too complex to ever be secure.

Unicode:
<http://www.unicode.org/>


My thanks to Jeffrey Streifling, who provided much of the material for this 
article.


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             Comments from Readers



From: Bernard Peek <Bernard@postar.co.uk>
Subject: Remotely Disabling Software

In the UK there is legal protection against disabling software by remote 
commands.  In general this is illegal without the users' prior consent.  It 
could be permitted if the user agreed to a software license that contained 
appropriate clauses.  As I understand it, in the absence of a prior 
agreement any supplier that disabled a program running on a machine in the 
UK would be committing an offence within UK jurisdiction.  Whether they 
triggered the event from elsewhere is not a defence.

I believe that one software supplier embedded an undisclosed time-trap in 
their program which would disable it.  The trap was sprung if the supplier 
failed to switch it off.  They would only do that if the customer failed to 
pay the final invoice.

One invoice was disputed and the trap was sprung.  The software supplier 
was successfully prosecuted and had to pay a fine and damages.

I note, with some interest, that some files have security certificates with 
expiry dates, and that some programs will not work with expired files.  I 
trust that the suppliers of these files have mechanisms in place to replace 
all of them prior to their expiry date, or have the customer's signature on 
a software license that details the conditions under which the programs 
cease to work.


From: Matt Curtin <cmcurtin@interhack.net>
Subject: Breaking DES Keys by Brute Force

In the June 15 issue of CRYPTO-GRAM, you discuss the (in)security of DES 
because of its relatively short key length.

 > Concerns about its short key length have dogged the
 > algorithm since the beginning, and in 1998 a brute-
 > force machine capable of breaking DES was built.

John Gilmore and company made an important advancement with Deep Crack in 
1998, breaking DES keys very quickly.  But the first break of a DES key was 
actually accomplished in 1997 in software by a team led by Rocke 
Verser.  Justin Dolske and I wrote a paper describing the architecture of 
the system that was published in the May 1998 special issue of ;login.

This seems an important thing to mention not just because we can move the 
time that it took to break DES keys back another year, but because it has 
been demonstrated (twice -- another team did the same thing the following 
year) that the key length was so short that it could be broken in software 
using only random idle cycles from computers talking together over a simple 
protocol.  Before this is dismissed as an impractical attack, consider that 
it's believed that recent distributed denial-of-service attacks have been 
perpetrated by attackers who take over others' machines without their 
knowledge and then coordinate these "zombie machines" to do their work.  If 
attackers can do this for launching DoS attacks, it could be done to break 
keys.  (Though because of the inefficiency of the attack, this won't be 
used for anyone but attackers with no money, I'd think...)

The technical article is online at 
<http://www.interhack.net/pubs/des-key-crack/> and a nontechnical article 
(originally written for the press) briefly describing cryptography, brute 
force attacks, and our project's success is at
<http://www.interhack.net/projects/deschall/what.html>.


From: Paul Bissex <pb@e-scribe.com>
Subject: Re: Cryptogram 6/15, Williams/Agre

A quick note on J. Christopher Williams' response to Phil Agre.  I believe 
Mr. Williams has a legitimate difference of opinion here, though I do not 
share his views.  However, to say that "[Agre's] grasp of basic grammar is 
less than firm" is simply laughable, especially after one has struggled 
through a few dozen lines of Mr. Williams' stilted prose.

There are few people who write about technology with as much intelligence, 
erudition, and accuracy as Phil Agre.  It is unfortunate that Mr. Williams 
felt the need to turn his nitpick into a personal attack.


From: "Jay R. Ashworth" <jra@baylink.com>
Subject: Comments to Schneier on Agre

In comments published in the June Cryptogram, Mr. Williams, you take issue 
with the comments by Phil Agre pointed to by, I believe, the previous 
edition of the newsletter...

Microsoft wrote:
 > "... This is by-design behavior, not a security
 > vulnerability."

Agre commented:
 > "More odd language.  It's like saying, 'This is a rock,
 > not something that can fall to the ground'.  It's
 > confusing to even think about it.
 > ..."

You observed:
 > The author may be a security or computer expert, but
 > his grasp of basic grammar is less than firm.  The more
 > accurate grammar conversion would be "This is an
 > object thrown to the ground, not a free-falling
 > object."  The statement in and of itself merely assists
 > in defining what can be called "thrown" and what can
 > be called "free-falling" campaign the author suggests.
 > To me the author is seemingly engaging in the same
 > "blame shifting tactic" that he accuses Microsoft of.

The way *I* see this is this:  Agre feels, and I agree with him, that 
Microsoft, in its phrasing, is suggesting that since [the behavior in 
question] is by design, that it *cannot be* a security vulnerability; that 
is, that they are mutually exclusive.

If in fact this is the assertion that Microsoft is trying to cause people 
to infer, they are wrong.  For evidence, we need merely look to one of the 
most famous security holes of all time: the sendmail DEBUG command.

Obviously this was placed in the software by design.  Equally obviously, it 
was a security vulnerability.  Therefore, it must be possible for an 
element of a program to be both of these things.

Therefore, Microsoft's explanation must be disingenuous, as they are trying 
to assert that these two descriptions of a part of a program cannot both 
simultaneously be true.

The problem isn't Phil doesn't understand the language, it's that Microsoft 
is playing fast and loose with it.


From: kragen@pobox.com (Kragen Sitaker)
Subject: Risks of XML

You write:
 > XML and how to secure it:
 > <http://www.zdnet.co.uk/news/2000/20/ns-15500.html>

This topic is sort of like "ASCII and how to secure it."  This paragraph 
says it best:

 > And that is the one big problem.  The Internet is as
 > insecure as ever, and ASCII will do nothing to improve
 > it.  In fact, the temptation to intercept and alter an
 > ASCII document containing vital data en route from one
 > banking application to another will lure many an
 > Internet vandal.

Well, in the original, it said XML, not ASCII, but it makes just as much 
sense either way.


From: Darren Cervantes <cervante@roguewave.com>
Subject: SOAP Security

Your newsletter was forwarded to me recently.  I am interested in your 
opinion on SOAP security issues.  Your recent article suggested that any 
SOAP command may be able to sneak through to your machine and do something 
malicious.  You state: Firewalls have good reasons for blocking protocols 
like DCOM coming from untrusted sources.  Protocols that sneak them through 
are not what's wanted.

In my understanding of the SOAP protocol, a few things have to happen in 
order for an RPC to "sneak" through:
1) An explicit SOAP server has to be set up
2) The SOAP server has to "translate" SOAP to enterprise services or RPCs
2) That server has to be configured to execute particular SOAP services (in 
other words if the service isn't defined, it isn't available through SOAP)
3) The server has an opportunity to recognize the SOAP service and refuse 
or block it if it is invalid

In addition, in the MS SOAP document, they state that both HTTP encryption 
(SSL) and HTTP authentication protocols can be used in conjunction with any 
end-point security (presumably authorization).  This would help negate the 
"untrusted sources" factor.

Based on my understanding, you would have to set up a SOAP server and an 
explicit service to "erase harddrive."  You would then have to allow your 
server to accept the request.  In a sense, it seems that this same concern 
could be equally applied to many other technologies.  If SOAP were to be 
implemented irresponsibly, it could certainly be insecure, but isn't it 
possible to implement it securely?


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