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The Information Systems Security Monitor
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Dedicated to the pursuit of security awareness............
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Volume 2 Number 1 January 1992
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////////////////////// In this Issue \\\\\\\\\\\\\\\\\\\\\\\\\\\
One Nerd's Approach to Computer Security
What did Clyde say?
Digital Signatures Still A Mystery to Many in Government
Cyberspace
Dear Clyde
Computer Speak
Virus Fighters
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ONE NERD'S APPROACH TO COMPUTER SECURITY
Hi, my name is Bill Strouse and I'm a NERD (Network Emergency
Repair Dude). I've been a Sysop or systems operator now for better
than a decade and I've learned a great deal about human nature and
security in general.
Back in 1980 it dawned on me that if I connected a modem to my
computer I could access it from anywhere I happened to be. But I
would have to have some sort of security or others would be
accessing it, possibly in a destructive way. The solution I decided
on was to setup a bulletin board system that used a combination of
a unique name and password for each caller to control what that
caller had access to. Once I got the system working I found it was
a great way to keep in touch with friends that also had modems and
an even better way to get answers on technical problems. Plus the
latest PD (public domain) software regularly showed up on my hard
disk. I publicized the number in electronic lists that were
distributed worldwide and was soon getting calls from all over the
continent and foreign countries like Sweden, England and Australia.
I soon had one of the best collections of PD software in the
country and the phone line was in constant use day and night.
Along with all the great people I met there were always those few
who had nothing better to do than try to destroy or disrupt what
others had built. One of the first things I learned was not to
allow just anyone the ability to leave public electronic mail.
Kids would call and leave grossly obnoxious public messages with
all sorts of foul language. We devised a system whereby a caller
could only leave a message to the Sysop on the first call then we
would call them back voice and verify who they were. Most
importantly we had verified they were connected to a legitimate
phone number which could be traced to a physical location and
person. After verification their security level was raised so they
had full access and an hour of system time a day. One of the next
lessons I learned was not to allow anyone to upload a program they
could then execute on the system. A friend, who continually worked
at busting the security to see if he could find holes uploaded a
game with a hidden copy of BASIC embedded in the program. When he
ran the program online he could issue a control code and jump to
the interpreter which allowed him to walk all over the security
like it didn't exist! After that all files were uploaded to a
private area no one but the Sysop had access to till they were
thoroughly inspected.
By 1985 I had so many people asking for help with computer related
problems I went into business for myself as a VAR, or Value Added
Reseller. Someone who not only sells you the goods but sticks
around and makes them work for you. Not long after that networking
looked like it might be the wave of the future. Since a network was
a shared resource, similar in nature to a bulletin board system and
even used a name and password for security I was right at home. And
I learned even more about security.
Number one. The weakest link in security is the employee using the
computer! They put their password on a sticky note and paste it on
their monitor so they don't forget; loan their account to fellow
employees; use passwords such as "secret", "love", or their social
security account number (every 14 year old wanna-be hacker has the
list of most commonly used passwords). They go to lunch and leave
their workstation logged into accounting records, bring in new
(virus infected) programs they want to use at work and just
generally gum up the (security) works. A good employee security
education program is worth its weight in gold.
And, security must be physical as well as electronic. I read a book
about a group of young hackers (Inner Circle) that could not
gain access to a mainframe because the security was well designed
so they posted a kid in the lobby of the company with a
questionnaire. He passed himself off as a high school student who
had been given an information gathering assignment as a school
project. Some of the questions asked were "What is your first and
last name", "Do you use a computer at work", "Are you married",
"What's your wife's name". Needless to say they were into the
system within days.
Mainframe managers are somewhat aware of this and protect their
iron (computers) from anyone without proper authority but most of
the LANs (Local Area Networks) I've worked with are in an area
that's easily accessible by anyone. Remember, something as simple
as a cup of coffee, or a boot disk with the proper utilities in
the hands of a disgruntled stockboy can turn your data into random
1s & 0s and truly ruin your day, if not your career.
The system I run is called The Ring of Fire after the tectonic
plate we live on the edge of here in California. Over time it has
grown to four (4) phone lines and over 350 megabytes of
downloadable software packages and graphics images. There are
well over 1,000 regular callers and the system averages about 3,000
calls a month but the electronic mail is where the real action is.
The E-mail is shared with other similar computer systems all over
the US and some foreign countries. Callers can leave a message in
a conference and it will show up on other systems all over the
country. Replies are automatically routed back to the originator
and show up as return mail addressed to that person. Thus, callers
can converse with a large number of diversely scattered individuals
at minimal cost (usually a free local phone call). To further
reduce online time we support SLMR off-line mail reader. With it
you can download a compressed mail packet of pre-specified
conferences then read and reply off-line with a full screen
editor and upload a compressed set of replies.
All of this runs on a Novell network that spans several computers
and large hard disks, a read/write CD, Fax server AND all of our
inhouse workstations. Hopefully, I'll see you online and we can
continue this as an interactive discussion ;-).
Author bio:
Bill Strouse has been a systems analyst for more
than twenty years now and has worked as a con-
sultant for IBM, Amdahl, Ford Aerospace and
Stanford University's SLAC (Stanford Linear
Accelerator).
Bill Strouse has been telecommuting since 1980
when he started his first electronic bulletin
board service, back in the CP/M days. He has
been the system operator ever since and current
ly has one of Silicon Valley's most popular
boards, the Ring-of-Fire, at 408-453-3326 and
408-453-2460. He was President of PRACSA (Public
Remote Access Computer Standards Association) for
many years before leaving three years ago to
found and become President of United Sysop's
Association, an organization of bulletin board
system operators and users.
Mr. Strouse is a president of Stoney River Net-
works, an authorized Novell Reseller. His com-
pany has installed many remote communication sys-
tems for various clients. He is also President
and Co-founder of the Silicon Valley Novell User
Group and serves on the Board of the Northern
California Netware User's Association. Bill is
also the editor of NetWare News, the newsletter
of the California Netware Users Association.
-------------------------End of Article---------------------
WHAT DID CLYDE SAY?
It's been brought to our attention that everyone that reads the
ISSM isn't always well versed in computer terminology. Well, in
an effort to remedy that situation we will be providing an article
called "Computer Speak", starting in this issue, that will be
devoted to getting every reader to understand computer jargon.
We appreciate hearing from our readers about any items or topics
that they would like to see appear in the ISSM. So let's keep
hearing from you. Just drop a note to Clyde or call.
-------------------------End of Article---------------------
DIGITAL SIGNATURES STILL ARE MYSTERY TO MANY IN GOVERNMENT
By Darryl K. Taft
A fight has erupted over the government proposal of a new
standard for digital signatures, and questions remain as to just
what a digital signature and public-key encryption actually are.
The National Institute of Standards and Technology has
proposed a standard for digital signatures that would securely
verify a message sender's identity.
Miles Smid, manager of the security technology group in NIST's
Computer Systems Laboratory, defined a "key" as a binary number
used with an algorithm to encipher or decipher data.
Public-key encryption requires the use of a matched pair of
such keys for each user, one that is publicly known and one that
is private and known only to the user. More traditional data
encryption methods, like the government's Data Encryption Standard
(DES), require only one key to encipher and decipher data.
Under the old method, "if I were to scramble a message with
my secret key, the only way you could descramble it would be to use
my key," Smid said. DES requires exchanging secret encryption keys
with each party, thus requiring prior relationships.
However, rather than using the same key to both encrypt and
decrypt the data, public-key encryption uses a matched pair of
encryption and decryption keys. Each key performs the inverse
function of the other.
Thus, a user makes his public-key publicly available, perhaps
via a directory or certifying authority, and keeps his private key
secret. To send a private message, an originator scrambles his
entire message using his intended recipient's public key. Once this
is done, the message can only be decoded with the recipient's
private key.
Inversely, a sender also can work over a file using his
private key, and it can only be decoded using that sender's public
key.
This provides the basis for the digital signature, because if
you can unscramble a signature in a message with someone's public
key, they had to use their private key to scramble it in the first
place.
The proposed standard, known as the Digital Signature Standard
(DSS) is based on a digital signature algorithm (DSA) derived from
a concept known as ElGamal encryption. It is intended for use in
electronic mail, electronic funds transfer, electronic data
interchange, software distribution, data storage and other
applications that require data integrity assurance and data origin
authentication.
NIST, on Aug.30, proposed to adopt the DSS as a Federal
Information Processing Standard (FIPS). The proposed standard
specifies a digital signature algorithm based on a public key.
The government's DSS is not intended to encrypt the data in
a message, but primarily to authenticate. The DSS is intended to
verify the author and verify the integrity of the data in the
message.
Public-key encryption algorithms are based upon what are known
as "hard problems," Smid said. These hard problems are mathematical
operations involving very large numbers. The government's proposed
DSS uses one of a variety of public-key encryption algorithms, Smid
said.
The NIST proposal's scheme differs markedly from that of a
popular encryption system from RSA Data Security Inc. of Redwood
City, Calif. The difference lies in the algorithms used to encrypt
and decrypt data. Smid said the RSA algorithm is based on the
difficulty of factoring very large numbers. This involves finding
a number that is the product of two other numbers.
Breaking that system for a small number would be pretty
simple, "but if I give you a large number, like 150 digits, that
would be difficult. Factoring very large numbers is a difficult
problem," he said.
The algorithm used in the NIST proposal is based upon the
difficulty of finding discrete logarithms. Essentially, this method
involves finding the remainder left over when you divide one number
by another one. Again, when dealing with very large numbers this
becomes a very difficult problem, Smid said.
Trap Doors
RSA's president, D. James Bidzos, has attacked the NIST
proposal as one that is not secure and that encourages trap doors.
Smid said many cryptographers rate the discrete logarithm problem
as more difficult or at least as difficult as the factoring method
RSA uses.
Ironically, Tahar ElGamal, whose work is recognized in the
NIST encryption scheme, is RSA's director of engineering.
"What NIST has proposed is a modification of the idea. Their
algorithm is about half from my work and half from theirs. The key
size is limited to 512 bits, which is questionable," ElGamal said.
ElGamal added that while he believes the NIST proposal will work,
he questions its security.
To use the DSS, a user need only use the system with his
everyday mail software.
"What you'd see is the regular message under whatever mail
system you have, but somewhere there would be a place for a digital
value, from three to 500 bits of data. This would be the sender's
signature. You'd have to have some software that would be able to
pull off the signature and verify it," Smid said.
Using the DSS, messages appear "in the clear," Smid said
because the DSS does not account for privacy. The DSS does not
encrypt the entire message, it adds an encrypted "signature" onto
the message.
The RSA system does allow for privacy -- with or without
another encryption scheme. The RSA system lets the user "sign" a
message with his private key and then add privacy by encrypting the
message with the recipient's public key. In trying RSA Data
Security's Mailsafe software for MS-DOS on the GCN local area
network, we found it to work quickly and easily, whether a message
was just "signed" or signed and "sealed."
Signed and Sealed
Signing the message with the sender's private key put an
encrypted digital signature at the end of an openly readable
message. Any person receiving the message with RSA software could
verify that it had not been changed and that it came from the
sender who scrambled the signature.
Sealing it with the recipient's public key then scrambled the
entire message so only the recipient could read it with his private
key.
At the receiving end, we decrypted the message first with the
recipient's private key, then verified the signature with the
sender's public key.
Full encryption and decryption took less than five seconds
each for a 10K file on AST Research Inc. Premium 386/25 computers.
Varying hard-drive speeds had no measurable effect at this file
size.
Though all this sounds very good, it appears to be practical
only in close-knit computing communities. As yet, no third-party
certification authorities have been established. To use these
schemes, users must be able to verify that a public-key/private-
key combination fits the right person. Without a certification
authority this is difficult in a large network.
The U.S. Postal Service is vying to provide that service.
Without certification of keys, someone could establish a key in
someone else's name.
The 90-day comment period for the NIST proposal ends at the
end of November, but NIST probably will not formally adopt the
standard until February, Smid said. The DSS would be mandatory for
federal users and for private companies protecting government data,
he said.
Though questioning claims that the DSS is less secure than
RSA's method, Smid acknowledged that the DSS lacks a necessary
hashing function. A hashing function is a cryptographic algorithm
used to create a message digest that is unique to each document,
much like a fingerprint, said Bidzos. This function ensures the
message has not changed since the sender "signed" it. However, Smid
said NIST will deliver a hashing function soon.
Public-key encryption is not simply a black art that just
happens. "To use public-key encryption, you need a system that
knows how to use it," said Robert E. Frank, project leader for
electronic commerce at the Lawrence Livermore National Laboratory
in Livermore, Calif.
Frank heads a Defense Department funded project to move DOD
to electronic commerce. One area his group has focused on is
public-key encryption. The pilot system that Lawrence Livermore has
developed gives users an option to use either the NIST proposal or
the RSA method.
"Our main objective is to provide a trusted mail capability
that makes it possible for vendors and government buyers to use the
security features if they want to, and to use what they're most
comfortable with," Frank said.
Reprinted with permission by Government Computer News, October 28,
1991, page 37. Copyright 1989, Ziff-Davis Publishing Company
-------------------------End of Article---------------------
...........................................................
A journey behind (way behind) . . . .
. . . . . .. .
. CYBERSPACE . . .. . .
. . . . . . .
hackers in their illusive world . .. . .
...........................................................
by Kim Clancy
In the last issue of the ISSM, I explained that I would be
documenting my journey behind hackers in cyberspace. Let me start
by saying that cyberspace is fascinating; it is another world that
quietly but actively exists. I mean ACTIVELY. I have no idea what
the traffic is of electronic interactions but I can tell you that
within minutes I can send a message to Japan and get a response.
I can write this article in West Virginia and send it in electronic
format to San Francisco. As a matter of fact, almost every guest
article we have received has been sent to us through cyberspace.
Within minutes of receiving the article, it is imported into the
newsletter and finalized. This is a fascinating technology.
The dark side of cyberspace
Alas, while the technology offers major advantages, it also
offers some very frightening avenues as well. What is scary to me
in regard to some of the avenues is the ability for individuals
to get to so many different types of information, individuals that
may initially be too naive to know what they are stumbling into.
I am not stating that I think information should be shielded from
individuals. I am saying that turning people, children for example,
loose in cyberspace may have some unpleasant results. I once went
to a presentation about hackers. The presenter told a story about
a mother who took her child's computer modem out into the driveway
and ran over it after her son had been arrested for hacking. The
presenter said that you should never let your child use a modem
unattended. While hackers spend time developing their skills and
learning how to master cyberspace they also use cyberspace to share
information about what they have learned. Information has been
found on how to steal long distance phone calls from the phone
company, how to make a pipe bomb and how to perform satanic rituals
before sitting down to hack. I hesitate to write the above because
I don't want people to avoid the technology. Everything I have
found is in most libraries, but the accessibility of it through
computers makes it much easier to obtain. In an earlier issue of
the ISSM, we published a code of computer ethics being used by
schools throughout the nation. If you have purchased a modem for
your child for Christmas, you may wish to dig that issue out and
go over that with him or her.
On a brighter note
I thoroughly enjoy cyberspace. Cyberspace has fantastic
legitimate resources and places to visit that are good for the
entire family. For example, you can dial up CompuServe and get
access to encyclopedias. This is a great way for a child to
research a school project. The AIS Security Branch accesses
numerous electronic bulletin boards(bbs) that keep us up to date
on security issues and provides us with a network of security
professionals. As a matter of fact, we actively participate in
cyberspace by running our own bbs.
There is really no way of knowing where a person will end up once
he/she starts exploring cyberspace. The technology is addictive and
before you know it you are constantly searching for more computers
to call and more people to learn from. Cyberspace is a great world,
but if you are not careful, it can carry you away. Don't ignore the
technology, if you don't know about it, you are already behind.
Dive in, experience it, have a great time. You will be fascinated
by what you discover.
-------------------------End of Article---------------------
/^\
_ /_ \_\ /\ Clyde....dedicated to the pursuit
/ /\ \ / \ of security ...
/__/ \__\ | |
@ @ ______
__ </ __ |
\ \______/ / |
\_______/ |
DEAR CLYDE...responses to questions for those who are searching for
the truth.............................................
Dear Clyde,
How do I select a good password?
Signed, ABCDE
Dear ABCDE,
One method is to choose a 5 or 6 character word at random and then
add 2 or more random characters to it. This should give you
something relatively easy to remember with the additional
characters making it more difficult to compromise. It is not a
good practice to choose a word that can be associated with you.
Send your comments or questions to Clyde c/o the AIS Security
Branch in Parkersburg, WV, Room 1011, or leave them in Clyde's
mailbox located on the Security bulletin boards located throughout
the Parkersburg office. You may also leave Clyde an email message
on the AIS Security Branches bbs (304-420-6083)
-------------------------End of Article---------------------
//Computer Speak: Computer terms and their meanings\\
SYSOP n. The operator (and usually the owner) of a bulletin-board
system.
MODEM n. A device that connects a computer and a terminal via a
telephone line. Short for modulator/demodulator.
NETWORK n. A data communications system that allows a number of
systems that allows a number of systems and devices to communicate
with each other.
TRAP DOOR alt. trapdoor n. A breach created intentionally in an EDP
systems for the purpose of collecting, altering, or destroying
data.
HARDWARE n. Physical equipment used in data processing. Such as
PC, disk drives, mainframe, keyboard, etc.
SOFTWARE n. Computer programs, procedures, rules, and possibly
associated documentation.
-------------------------End of Article---------------------
^^^^^VIRUS FIGHTERS
What is a computer virus?
The term "computer virus" is derived from and analogous to a
biological virus. The word virus itself is Latin for poison.
A computer virus is a computer program that will copy (infect) its
code into the machine codes of other programs, and when those
infected programs are run performing some apparently useful
function, such as a login, it executes its hidden code performing
an unwanted, usually malicious function.
How does a computer virus work?
A program infected with a virus and loaded and executing in the
main memory of a computer can infect another executable (object)
program in the computer's disk storage system by secretly
requesting the computer's operating system to append a copy of the
virus code to the object program, usually at the start. The
infection makes the object program slightly longer.
When the newly infected program is itself loaded into memory and
invoked, the virus in it takes control and performs hidden
functions, such as infecting yet other object programs. The virus
may also perform destructive functions before transferring control
to the original entry point. The virus code contains a marker so
that the virus won't attempt to infect a program already infected
by its own kind: multiple infections would cause an object file to
grow ever larger, leading to easy detection.
The same principle works in personal computers, where floppy disks
play the role of object programs in the description above. In this
case, the virus usually attacks the copy of the operating system
contained on the floppy disk so that the virus is automatically
invoked whenever the disk's operating system is started. Since the
operating system then resides in the PC's main memory, it can
infect any diskettes inserted into the PC.
What can be done to protect against viruses in a computer or
workstation?
An additional measure of protection can be obtained by care in the
way one uses a computer. Analogies with food and drug safety are
helpful. Just as one would not consider purchasing food or
capsules in unsealed containers or from untrusted sources, one can
refuse to use any unsealed software or software from untrusted
sources.
Can the operating procedures followed by those who use a computer
system lower the risk?
Yes! The following are some procedures that would help lower the
risk:
. Never insert a diskette that has no manufacturer's seal into your
PC.
. Never use a program borrowed from someone who does not practice
digital hygiene to your own standards.
. Beware of software obtained from public bulletin boards.
. Purchase programs that check other programs for known viruses.
. Be wary of public domain software (including virus eradicators!).
. Monitor the last-modified dates of programs and files.
. Don't execute programs sent in electronic mail--even your friends
may have inadvertently forwarded a virus.
. Don't let employees bring software from home, unless it is
approved and checked to be virus free by user management.
What are some of the computer virus symptoms?
When a strange behavior occurs, do not dismiss it as simply a bug.
Instead, suspect a virus and respond accordingly - acting quickly
may save your data. The following are possible symptoms of a viral
infection:
. Strange screen graphics or displays.
. Unexpected musical tones or sound effects.
. Alteration of text or commands.
. Unusual behavior on reboot.
. Reduction in system performance.
. Unexpected disk access patterns.
. Changes in file length or alteration times.
. Bugs in previously reliable software.
. Bad sectors on floppy disks, or unusually large numbers of bad
sectors on hard disks.
. Reduction in available memory.
. Unexplained changes in the system clock.
. Unknown, new files or directories/folders appearing on disk.
. Problems in time-dependent tasks such as communications or
printing.
. The system will not reset or reboot.
What to do if you expect a virus.
. Leave the machine on! Any evidence of intrusion or
infection may be lost if the machine is powered down. Turn off
the machine only at the instruction of your management, your
security group, or your technical support group.
. If your desk-top computer is connected to any kind of network,
break the network connection logically.
NOTE: BPD EMPLOYEES MUST CONTACT THE COMMUNICATIONS BRANCH IN THE
DIVISION OF PROGRAMS AND COMMUNICATIONS (OAIS) SO THAT THEY
MAY BREAK THE PHYSICAL CONNECTION.
. Let people know about your suspicions. Alert your own
management.
. Use your regular trouble reporting procedure to notify technical
support of your problem.
Additional information on viruses can be obtained from publications
available in the AIS Security Branch. The information above was
obtained from the publication "Computers Under Attack - Intruders,
worms, and Viruses" by Peter J. Denning.
-------------------------End of Article---------------------
DON'T FORGET, THE AIS SECURITY BRANCH RUNS ITS OWN ELECTRONIC
BULLETIN BOARD SYSTEM(BBS). GIVE US A CALL AND LET US KNOW WHAT
YOU THINK. THE NUMBER IS 304-420-6083.
The ISSM is a quarterly publication of the Department of Treasury,
Bureau of the Public Debt, AIS Security Branch, 200 3rd Street,
Parkersburg, WV 26101, (304) 420-6363. The ISSM is also available
in paper format. Let us know if you would like a copy or if you
would like to download a copy of the print file. The print file
can be copied to a HP II or III laser printer and you will receive
a copy with all graphics and formatting.
Editors: Bob Settles, Ed Alesius, Kim Clancy, Joe Kordella
Downloaded From P-80 International Information Systems 304-744-2253