Vesselin Bontchev, Director
Laboratory of Computer Virology
Bulgarian Academy of Sciences, Sofia, Bulgaria

0) Abstract
===========

It is now well known that Bulgaria is leader in computer virus
production and the USSR is following closely. This paper tries to
answer the main questions: Who makes viruses there, What viruses are
made, and Why this is done. It also underlines the impact of this
process on the West, as well as on the national software industry.

1) How the story began
======================

Just three years ago there were no computer viruses in Bulgaria.
After all, these were things that can happen only in the capitalist
countries. They were first mentioned in the April issue of the
Bulgarian computer magazine "Komputar za vas" ("Computer for you")
[KV88] in a paper, translated from the German magazine "Chip" [Chip].
Soon after that, the same Bulgarian magazine published an article
[KV89]], explaining why computer viruses cannot be dangerous. The
arguments presented were, in general, correct, but the author had
completely missed the fact that the majority of PC users are not
experienced programmers.

A few months later, in the fall of the same year, two men came in the
editor's office of the magazine and claimed that they have found a
computer virus. Careful examination showed that it was the VIENNA
virus.

At that time the computer virus was a completely new idea for us. To
make a computer program, whose performance resembles a live being, is
able to replicate and to move from computer to computer even against
the will of the user, seemed extremely exciting.

The fact that "it can be done" and that even "it had been done"
spread in our country like wildfire. Soon hackers obtained a copy of
the virus and began to hack it. It was noticed that the program
contains no "black magic" and that it was even quite sloppily
written. Soon new, home-made and improved versions appeared. Some of
them were produced just by assembling the disassembly of the virus
using a better optimizing assembler. Some were optimized by hand. As
a result, now there are several versions of this virus, that were
created in Bulgaria - versions with infective lengths of 627, 623,
622, 435, 367, 353 and even 348 bytes. The virus has been made almost
two times shorter (its original infective length is 648 bytes)
without any loss of functionality.

This virus was the first case. Soon after that, we were "visited" by
the CASCADE and the PING PONG viruses. The later was the first
boot-sector virus and proved that this special area, present on
every diskette can be used as a virus carrier, too. All these three
viruses were probably imported with illegal copies of pirated
programs.

2) Who, What & Why.
===================

2.1) The first Bulgarian virus.
------

At that time both known viruses that infected files ( VIENNA and
CASCADE) infected only COM files. This made me believe that the
infection of EXE files was much more difficult. Unfortunately, I made
the mistake by telling my opinion to a friend of mine. Let's call him
"V.B." for privacy reasons.(1)
...................................................................
[(1) These are the initials of his true name. It
will be the same with the other virus writers that I shall mention.
Please note, that while I have the same initials (and even his full
name resembles mine), we are two different persons.]
...................................................................
The challenge was taken immediately and soon after that I received a
simple virus that was able to infect only EXE files. It is now known
to the world under the name of OLD YANKEE. The reason for this is
that when the virus infects a new file, it plays the "Yankee Doodle"
melody.

The virus itself was quite trivial. Its only feature was its ability
to infect EXE files. The author of this virus even distributed its
source code (or, more exactly, the source code of the program that
releases it). Nevertheless, the virus did not spread very widely and
even had not been modified a lot. Only a few sites reported to be
infected by it. Probably the reason for this was the fact, that the
virus was non-resident and that it infected files only on the
current drive. So the only possibility to get infected by it was to
copy an infected file from one computer to another.

When the puzzle of creating a virus which is able to infect EXE files
was solved, V.B. lost his interest in this field and didn't write any
other viruses. As far as I know, he currently works in real-time
signal processing.

2.2) The T.P. case.
----

The second Bulgarian virus-writer, T.P., caused much more trouble.
When he first heard the idea about aself-replicating program, he was
very interested, decided to writehis own virus, and he succeeded.
Then he tried to implement a virus protection scheme and succeeded
again. The next move was to improve his virus to bypass his own virus
protection, then to improve the virus protection and so on. That is
why there are currently about 50 different versions of his viruses.

Unfortunately, several of them (about a dozen) were quite
"successful." They spread world-wide. There are reports about them
from all countries of the former Eastern block, as well as from the
USA and West Europe.

Earlier versions of these TP viruses are known under the name
VACSINA, because they contain such a string. In fact, this is the
name of the virus author's virus protection program. It is
implemented as a device driver with this name. The virus merely tries
to open a file with this name, which means "Hey, it's me, let me
pass."

The latest versions of the virus are best known under the name YANKEE
DOODLE, because they play this tune. The conditions on which the tune
is played are different with the different versions of the virus -
for instance when the user tries to reboot the system, or when the
system timer reaches 5 p.m.

All TP viruses are strictly non-destructive. Their author payed
particular attention not to destroy any data. For instance, the virus
does not infect EXE files for which the true file length and the
length of the loadable part as it is present in the EXE header, are
not equal. As far as I know, no other virus that is able to infect
EXE files works this way.

Also, the virus does not try to bypass the resident programs that
have intercepted INT 13h, therefore it takes the risk to be detected
by most virus activities monitoring software. The author of the virus
obviously could circumvent it - for instance it uses a clever
technique, now known as "interrupt tracing" to bypass all programs
that have hooked INT 21h. The only reason for not bypassing INT 13h
as well, is that this would also bypass all disk casheing programs,
thus it could cause damage.

Of course, the fact that the virus is not intentionally destructive
does not mean that it does not cause any damage. There are several
reports of incompatibilities with other software; or of panicking
users, that have formatted their disks; or, at least, damage caused
by time loss, denial of computer services, or expenses removing the
virus. It is well known, that "there ain't no such thing as a good
virus."

The TP viruses were not spread intentionally; the cause could be
called "criminal negligence." The computer used by T.P. to develope
his viruses was also shared by several other people. This is common
practice in Bulgaria, where not everyone can have a really "personal"
computer to work with. T.P. warned the other users that he is writing
viruses, but at this time computer viruses were a completely new
idea, so nobody took the warning seriously. Since T.P. didn't bother
to clean up after himself, these users got, of course, infected.
Unintentionally, they spread the infection further.

When asked about the reason of writing viruses, T.P. replied that he
did this in order to try several new ideas; to better learn the
operating system and several programming tricks. He is not interested
in this field any more - he has stopped writing viruses about two
years ago.

2.3) The Dark Avenger.
----

In the spring of 1989 a new virus appeared in Bulgaria. It was
obviously "home-made" and just to remove any doubts about it, there
was a string in it, saying "This program was written in the city of
Sofia (C) 1988-89 Dark Avenger."

The virus was incredibly infectious - when it was in memory, it was
sufficient to copy or just to open a file to get it infected. When
the user felt that there is a virus in his/her system and, without
booting from a non-infected write-protected system diskette, ran an
anti-virus program which wasn't aware of this new virus, he usually
got all his/her executable files infected.

The idea of infecting a file when it is opened was new and really
"successful." Now such viruses are called "fast infectors." This
strategy helped the virus to spread world- wide. There are reports
from all European countries, from the USA, the USSR, even from
Thailand and Mongolia.

On the top of this, the virus was very dangerously destructive. On
each 16th run of an infected program, it overwrote a sector on a
random place of the disk, thus possibly destroying the file or
directory that contained this sector. The contents of the overwritten
sector was the first 512 bytes of the virus body, so even after the
system has been cleaned up, there were files, containing a string
"Eddie lives...somewhere in time!" This was causing much more damage
than if the virus was just formatting the hard disk, since the
destruction was very unnoticable and when the user eventually
discovered it, his backups probably already contained corrupted data.

Soon after that, other clever viruses began to appear. Almost all of
them were very destructive. Several contained completely new ideas.
Now this person (we still cannot identify him exactly) is believed to
be the author of the following viruses:

DARK AVENGER, V2000 (two variants), V2100 (two variants), 651,
DIAMOND (two variants), NOMENKLATURA, 512 (six variants), 800, 1226,
PROUD, EVIL, PHOENIX, ANTHRAX, LEECH...

Dark Avenger has several times attacked some anti-virus researchers
personally. The V2000/V2100 viruses claim to be written by "Vesselin
Bontchev" and in fact hang the computer when any program, containing
this string is run. A slightly modified variant of V2100 (V2100-B)
has been used to trojanize version 66 of John McAfee's package
VIRUSCAN.

There are reports that Dark Avenger has called several bulletin board
systems in Europe and has uploaded there viruses. The reports come
from the UK, Sweden, the Netherlands, Greece... Sometimes the viruses
uploaded there are unknown in Bulgaria (NOMENKLATURA,ANTHRAX). But
they are obviously made in our country - they contain messages in
Cyrillic. Sometimes Dark Avenger uploads a Trojan program that
spreads the virus - not just an infected program. This makes the
detection of the source of infection more difficult.

One particular case is when he has uploaded a file called UScan,
which, when run, claims to be the "universal virus scanner," written
by Vesselin Bontchev. Even the person who has uploaded it, has logged
under the name "Vesselin Bontchev." In fact, the program just
infected all scanned files with the ANTHRAX virus.

While the other Bulgarian virus writers seem to be just irresponsible
or with childish mentality, the Dark Avenger can be classified as a
"technopath." He is a regular user of several Bulgarian bulletin
board systems, so one can easily exchange e-mail messages with him.
When asked why his viruses are destructive, he replied that
"destroying data is a pleasure" and that he "just loves to destroy
other people's work."

Unfortunately, no measures can be taken against him in Bulgaria.
Since there is no law for information protection, his activities are
not illegal there. He can be easily caught by tapping the phones of
the BBSes that he uses, but the law enforcement authorities cannot
take such measures, since there is no evidence of illegal activities.
Alas, he knows this perfectly.

2.4) Lubo & Ian.
---

Some of the Dark Avenger's viruses proved to be very "successful" and
caused real epidemics. That is why they were often imitated by other
virus writers, that had no imagination to design their own virus, but
were jealous of Dark Avenger's fame. So they just disassembled his
viruses (usually the first one) and used parts of it - sometimes
without even understanding their purpose. Such is the case with the
MURPHY viruses.

According to a string in them, they are written by "Lubo & Ian, USM
Laboratory, Sofia." These people do exist and they have used their
real names. "Lubo" has even been several times interviewed by
newspaper's reporters.

They claim that the virus was written for vengeance. They have done
some important work for their boss and the latter refused to pay
them. That is why they developed te virus in one night and released
it. The fact that the virus will spread outside the laboratory just
didn't come to their minds. However, this does not explain the
developing of the other versions of the same virus (there are at
least four variants). Nevertheless, it proves one more time that it
is better (and safer, too) to pay the good programmers well...

Besides MURPHY, these two virus writers have created another virus,
called SENTINEL (5 variants). The only unusual thing with this virus
is that it is written in a high-level programming language (Turbo
PASCAL), but is not an overwriting or a companion virus as most HLL
viruses are. It is able to infect COM and EXE files by appending
itself to them and by preserving their full functionality. It is also
memory resident, hides the file length increase when the user issues
the DIR command, and even mutates.

2.5) The virus writer from Plovdiv.
-------

This man, P.D., claimed that he has written viruses "for fun" and
only "for himself" and that he "never releases them." Unfortunately,
at least two of them have "escaped" by accident. These are the ANTI-
PASCAL605 and the TERROR viruses. Especially the latter is extremely
virulent and caused a large epidemic in Bulgaria.

P.D. was very sorry for that and submitted examples of all his
viruses to the anti-virus researchers so that the respective
anti-virus programs be developed - just in case some of these
viruses escapes too. These viruses turned out to be quite a few,
ranging from extremely stupid to very sophisticated. Here are some of
them:

XBOOT, ANTIPASCAL (5 variants), TINY (11 variants), MINIMAL-45,
TERROR, DARK LORD, NINA, GERGANA, HAPPY NEW YEAR (2 variants), INT
13.

P.D. claims that the DARK LORD virus (a minor TERROR variant) is not
written by him. The TINY family has nothing to do with the Danish
TINY virus (the 163-byte variant of the KENNEDY virus), and, as well
as the MINIMAL-45 virus, are written with the only purpose to make
the shortest virus in the world.

Now P.D. is not writing viruses any more - because "it is so easy,
that it is not interesting," according to his own words. He is
currently writing anti-virus programs - and rather good ones.

2.6) The two guys from Varna.
------

They are two pupils (V.P. and S.K.) from the Mathematical High School
in Varna (a town on the Black Sea). They have developed several
viruses and continue to do so, producing more and more sophisticated
ones. Furthermore, they intentionally spread their viruses, usually
releasing them on the school's computers or in the Technical
University in Varna. When asked why they write and release viruses,
they reply "because it's so interesting!"

The viruses written by them are: MG (5 variants), SHAKE (5 variants),
DIR and DIR II. All of them are memory resident and infect files when
the DIR command is performed.

The last one is an extremely virulent and sophisticated virus - as
sophisticated, as THE NUMBER OF THE BEAST. It is also a completely
new type of virus - it infects nether boot sectors, nor files.
Instead, it infects the file system as a whole, changing the
information in the directory entries, so that each file seems to
begin with the virus.

There is a counter of the number of infected systems in the virus
body. There is evidence that V.P. and S.K. collect infected files,
copy the contents of the counter and then draw curves of the spread
of infection, checking the normal distribution law. They are doing
this "for fun."

2.7) W.T.'s case.
----

W.T. is a virus writer from Sofia, who has written two viruses -
WWT (2 variants) and DARTH VADER (4 variants). According to his own
words, he has done so to test a new idea and to gain access to the
Virus eXchange BBS (see below).

The new idea consisted of a virus (DARTH VADER) that does not
increase file lengths, because it searches for unused holes, filled
with zeros, and writes itself there. Also, the virus does not perform
any write operations. Instead, it just waits for a COM file to be
written to by DOS and modifies the file's image in memory just before
the write operation is performed.

W.T. does not write viruses any more, but he is still extremely
interested in this field. He is collecting sophisticated viruses and
disassembles them, looking for clever ideas.

2.8) The Naughty Hacker.
----

This virus writer, M.H., is a pupil and also lives in Sofia. He has
written several viruses, most of which contain the string "Naughty
Hacker" in their body. All of them are non- destructive, but contain
different video effects - from display desynchronization to a
bouncing ball.

Currently, at least 8 different variants are isolated, but it is
believed that even more exist and are spread in the wild. Also, it is
believed that M.H. continues to produce viruses. As usual, he is
doing so "because it is interesting" and "for fun."

He is also the author of three simple boot sector viruses (BOOTHORSE
and two others that are still unnamed).

2.9) Other known virus writers.
------

The persons listed above are the major Bulgarian virus producers.
However, they are not alone. Several other people in Bulgaria have
written at least one virus (sometimes more). In fact, making a virus
is currently considered there a kind of sport, or a practical joke,
or means of self-establishment.

Some of these virus writers have supplied their creations directly to
the anti-virus researchers, as if they are waiting for a reward.
This happens quite often - probably they expect that the
anti-virus researcher, as the best qualified person, will evaluate
their creation better. Sometimes the fact that their virus becomes
known, is described, and is included in the best anti-virus programs
is sufficient for these people and they don't bother to really spread
their virus in the wild. So, probably the main reason for these
people to produce viruses is the seek of glory, fame, and
self-establishment.

Such known Bulgarian virus writers (with the respective names of
their viruses given in parentheses) are V.D. from Pleven (MICRO-128),
A.S. and R.D. from Mihajlovgrad (V123), I.D. from Trojan (MUTANT,
V127, V270x), K.D. from Tutrakan (BOYS, WARRIER, WARRIOR, DREAM), and
others.

2.10) Unknown Bulgarian virus writers.
-------

Of course, there are also other virus writers, that are not known to
the author of this paper. Sometimes it is possible to determine the
town where the viruses were developed - usually due to an
appropriate string in the virus body, or because the virus wasn't
found elsewhere. Some of the viruses are very simple, others are
quite sophisticated. Here are examples of such viruses.

- The KAMIKAZE virus has been detected only in the Institute of
Mathematics at the Bulgarian Academy of Sciences, Sofia and is
probably made there;

- The RAT virus, made in Sofia, as it is written in its body;

- The VFSI (HAPPY DAY) virus has been developed in the Higher
Institute of Finances and Economics in Svishtov (a small town on the
Danube) by an unknown programmer;

- The DESTRUCTOR virus, probably made in Plovdiv, where it has been
first detected;

- The PARITY virus, probably written in the Technical University,
Sofia, since it has not been detected elsewhere;

- The TONY file and boot sector viruses, probably created in Plovdiv
where they have been first detected;

- The ETC virus, detected only in Sofia;

- The 1963 virus, a quite sophisticated one, probably made in the
Sofia University;

- The JUSTICE virus.

2.11) The Virus eXchange BBS.
------

About a year ago, the virus writing in Bulgaria entered a new phase.
The virus writers began to organize themselves. The first step was
the creation of a specialized bulletin board system (BBS), dedicated
to virus exchange. The Virus eXchange BBS.

It's system operator (SysOp), T.T. is a student of computer science
in the Sofia University. He has established the BBS in his own home.
On this BBS, there are two major kinds of files - anti-virus
programs and viruses. The anti-virus programs can be downloaded
freely.

In order to get access to the virus area, one has to upload there a
new virus. However, anyone who uploads a new virus, gets access to
the whole virus collection. S/He could then download every virus that
is already available, or even all of them. No questions are asked -
for instance for what reason s/he might need these viruses.

Furthermore, the SysOp takes no steps to verify the identity of his
users. They are allowed to use fake names and are even encouraged to
do so. Dark Avenger and W.T., between them are, the most active
users, but there are also names like George Bush from New York,
Saddam Hussein from Baghdad, Ozzy Ozburn and others.

Since this BBS has already a large collection of computer viruses
(about 300), it is quite difficult to find a new virus for it. If one
wants badly to get access to the virus area, it is much simpler to
write a new virus, instead of trying to find a new one. That is
exactly what W.T. did. Therefore, this BBS encourages virus writing.

Furthermore, on this BBS there are all kinds of viruses - some of
them as 1260, V2P6Z, FLIP, WHALE are considered as extremely
dangerous, since they are using several new ideas and clever tricks,
which makes them very difficult to be recognized and removed from the
infected files. And the Virus eXchange BBS policy makes all these
viruses freely available to any hacker that bothers to download them.
This will, undoubtedly, lead to the creation of more and more such
"difficult" viruses in the near future.

The free availability of live viruses has already given its bitter
fruits. It helped to viruses created far away from Bulgaria and not
widely spread, to cause epidemics in our country. Such was the case
of the DATALOCK virus. It has been created in California, USA and
uploaded to the Virus eXchange BBS. A few weeks later it was detected
in the Technical University, Sofia. Probably one of the users of the
BBS had downloaded it from there and spread it "for fun." In the
similar way the INTERNAL, TYPO and 1575 viruses entered our country.

But the free availability of known live viruses is not the most
dangerous thing. After all, since they are already known, there
already exist programs to detect and probably to remove them. Much
more dangerous is the free availability on this BBS of virus source
code! Indeed, original source code or well commented virus
disassemblies of several viruses are freely available on the Virus
eXchange BBS - just as any other live virus. To name a few, there
are:

DARK AVENGER, OLD YANKEE, DIAMOND, AMSTRAD, HYMN, MLTI830, MURPHY,
MAGNITOGORSK, ICELANDIC, MIX1, STONED, JERUSALEM, DATACRIME, BURGER,
ARMAGEDON, OROPAX, DARTH VADER, NAUGHTY HACKER, 512, VIENNA, 4096,
FISH#6, PING PONG, BLACK JEC, WWT, MG, TSD, BOOTHORSE, BAD BOY,
LEECH...

Most of them are perfectly assemblable sources.

The publishing of virus source code has proven to be the most
dangerous thing in this field. The VIENNA, JERUSALEM, CASCADE and
AMSTRAD viruses are the best examples. Their source code has been
made publicly available, which led to the creation of scores of new
variants of these viruses. The known variants of only these four
viruses are about 20 % of all known viruses, which means more than a
hundred variants. One can imagine the consequences of making publicly
available the source code of all the viruses listed above. In less
than a year we probably will be submerged by thousands new
variants...

In fact, this process has already begun. The HIV, MIGRAM, KAMASYA,
CEMETERY and ANTICHRIST viruses have been obviously created by
someone who had access to the source of the MURPHY virus. The ENIGMA
virus is clearly based on the OLD YANKEE code. There have been
reports about infections with these viruses in one Italian school and
an Italian virus writer, known as Cracker Jack is a user of Virus
eXchange...

The damage caused by this BBS alone to the rest of the world is big
enough. But this is not all. Since possession of "viral knowledge"
(i.e., live viruses, virus source code) has always tempted hackers
and since the legitimate anti-virus researchers usually exchange
such things only between themselves and in a very restricted manner,
it is not surprising that similar "virus boards" began to pop up
around the world. There are currently such BBSes in the USA, Germany,
Italy, Sweden, Czechoslovakia, the UK and the Soviet Union. Stopping
their activities is very difficult in legal terms, because the
possession, storage or willful downloading of computer viruses
usually is not considered as a criminal offence. And it shouldn't be
- otherwise the anti-virus researchers themselves will not have a
way to exchange virus samples to work with.

The creation of a virus-oriented BBS, the system operator of which
supported the writing, spreading and exchanging of virus code didn't
go unnoticed in Bulgaria. Almost all virus writers have obtained a
modem (a not very easy thing in Bulgaria) and contacted it.
Afterwards, they began to contact each other by means of electronic
messages on this BBS. They have even created a specialized local
conference (local for Bulgaria), in order to keep in touch and to
exchange ideas how to write clever viruses. Therefore, they began to
organize themselves - a thing that cannot be said about the
anti-virus research community in all countries...

3) New ideas.
=============

As it can be seen from the examples above, the whole of Bulgaria has
turned into some kind of computer virus developing laboratory, where
any capable (or not so capable) pupil/student/ programmer is tempted
to write his own virus and to test it in the wild. It is not
therefore unusual that several completely new ideas were first
developed in our country. I shall try to enumerate here some (only
the most important) of them.

- The interrupt tracing technique, capable of finding the original
handler (in DOS or BIOS) of any interrupt vector, has been first
implemented in the YANKEE DOODLE (TP) viruses. Later other viruses in
the world began to use it (4096, NAUGHTY HACKER).

- The "fast infectors" - viruses that infect on file opening or
even on any file operation were first developed in Bulgaria. The
first such virus was the DARK AVENGER. Now there are a lot of fast
infectors. One of them - 1963 - even infects on file deletion.

- The "semi-stealth" viruses - viruses that hide the increasing of
the size of the infected files (the 651 virus) or that remove them
from the infected files when one loads them with a debugger (YANKEE
DOODLE) both are viruses, made in our country.

- Hiding the true file length usually causes problems, because CHKDSK
is able to detect the difference between the disk space marked as
used in the FAT and the reported file length. Only two Bulgarian
viruses in the world are able to handle this problem - DIAMOND and
V2100.

- The first really "stealth" file infector - the 512 virus was
Bulgarian. It is true however, that the idea has been discovered
independently almost at the same time in other parts of the world
(the 4096 virus from Israel).

- The only known stealth parasitic virus, which "stealthy" features
go down to the BIOS level (i.e., it cannot be detected if active in
memory even if the infected file is read at sector and not at file
level) is the Bulgarian INT13 virus.

- One of the first multi-partite viruses (viruses that are able to
infect both files and boot sectors) - the ANTHRAX virus, has been
developed in Bulgaria. It is true, however, that similar ideas can be
noticed in the 4096 and GHOST BALLS viruses, which are developed much
earlier. Also, other multi-partite viruses (VIRUS-101, V-1, FLIP,
INVADER) were created independently almost at the same time (and even
earlier) in other parts of the world.

- The idea first used in the LEHIGH virus - to place the virus body
in an unused part of the file COMMAND.COM has been further developed
by several Bulgarian viruses. They all can infect any COM or EXE file
(unlike the LEHIGH virus) in the usual way, but when they are
infecting the command interpreter, they place themselves in an area
filled with zeros at the end of the file and thus in this case they
do not increase its length. Such viruses are TERROR, NAUGHTY HACKER
and others.

- The method, mentioned above has been developed even further by
other Bulgarian viruses. They have noticed that any sufficiently
large area of zeros in any file (not just COMMAND.COM) can be used to
hide the virus body. The viruses that use this method are again of
Bulgarian origin - PROUD, EVIL, PHOENIX, RAT, DARTH VADER... The
latter even does not write to the infected files - it leaves this
task to DOS. And the RAT virus hides itself into the unused part of
the EXE file headers.

- One of the extremely mutating viruses is the Dark Avenger's virus
LEECH. It can exist in more than 4.5 billion variants. It is true,
however, that this is neither the first entirely mutating virus (1260
being the first), nor it has the most flexible mutating mechanism (it
is much simpler than V2P6Z).

- A completely new type of computer virus (DIR II) has been developed
by two Bulgarian pupils. This virus does not infect neither files,
nor boot sectors. Instead, it infects file systems as a whole, or
more exactly - directory entries.

- Different tricks to get control without directly hooking the INT
21h vector were developed by several Bulgarian virus writers. The
TERROR virus places a JMP instruction to its body in the original INT
21h handler in DOS. The viruses from the PHOENIX family ( 800, 1226,
PROUD, EVIL, PHOENIX) hook an interrupt that is called by DOS on
every file-related function (INT 2Ah, AH=82h). The DIR II virus
patches itself in the chain of DOS disk device drivers.

- The first virus, that is able to infect device drivers (SYS files
only), is, of course, Bulgarian. This is the HAPPY NEW YEAR ( 1600)
virus.

- The first fully functional parasitic virus, written entirely in a
high level language (Turbo PASCAL) is the Bulgarian virus SENTINEL.

- The Bulgarian virus ANTHRAX is the first virus that is resident in
memory only temporary. It removes itself from there after it has
infected the first file and then acts as a non-resident virus.

- The shortest memory resident virus in the IBM PC world - only 128
bytes - is again developed in Bulgaria. There are reports about a
108-byte resident virus, also from there, but they are unconfirmed
yet.

- The shortest virus in the IBM PC world - only 45 bytes long, is
the Bulgarian virus MINIMAL-45. It seems possible, however, to
shorten it even further - up to 31 bytes, with a big loss of
reliability.

4) Why so many viruses are created in Bulgaria.
===============================================

Computer viruses are created in all parts of the world, not only in
Bulgaria. However, the portion of them that are created in our
country is extremely high. Therefore, in the whole world there exist
preconditions that make virus writing tempting, but in Bulgaria there
exist specific conditions as well.

4.1) Specific reasons for virus writing in Bulgaria.
---------

4.1.1)

The first, and most important of all is the existence of a
huge army of young and extremely qualified people, computer wizards,
that are not actively involved in the economic life.

The computerization in Bulgaria began without economical reasons.
Since our country was a socialist one, its economics was of
administrative type. The economics didn't need to be computerized. In
fact, computers and planned economics are quite incompatible -
computers help you to produce more in less time and with less effort
and money, while the goal of a manager in a planned economics is to
fulfil the plan exactly as it is given - for no more and no less
time, and with no more and no less money. However, the communist
party leaders in Bulgaria decided that we should computerize -
mainly to be able to supply computers to the Soviet Union and
circumvent the embargo.

While computerization in itself is not a bad thing, we made a very
severe mistake. Bulgarian economics was very weak (now it is even
weaker), but we had quite a lot skilled people. Therefore, we should
not have tried to produce hardware while we had good chances in the
software industry, where mainly "brainware" is required. However,
Bulgaria did just the opposite. Instead of buying the hardware, we
began to produce it (mainly illegal Apple and IBM clones). Instead of
producing our own software and to try to sell it in the West, we
began to steal Western computer programs, to change some copyright
notices in them, and to re-sell them (mainly in Bulgaria, in the
Soviet Union, and in the other countries of the former Eastern
block).

At that time most Western software was copy protected. Instead of
training our skilled people in writing their own programs, we began
to train them to break copy protection schemes. And they achieved
great success in this field. The Bulgarian hackers are maybe the best
in cracking copy protected programs. Besides, they had no real hope
in making and selling their own programs, since, due to the total
lack of copyright law on computer software, it was impossible to sell
more than two or three examples of a computer program in Bulgaria.
The rest were copied.

Since the introduction of computers in the Bulgarian offices was not
a natural process, but due to an administrative order, very often
these computers were not used - they were only considered as an
object of prestige. Very often on the desk of a company director,
near the phone, stood a personal computer. The director himself
almost never used the computer - however sometimes his/her children
came to the office to use it - to play games or to investigate its
internals. While the price of personal computers in Bulgaria was too
high to permit a private person to have his/her own computer, it was
a common practice to use the computer at the office for personal
reasons. At the same time, the computer education was very widely
introduced in Bulgaria. Everyone was educated in this field - from
children in the kindergartens to old teachers that had just a few
years until pension. Since this kind of science is better
comprehended by younger brains, it is no wonder that the people, who
became most skilled in this field, were very young. Very young and
not morally grown-up. We spent a lot of effort teaching these people
how to program, but forgot to educate them in computer ethics.
Besides, the lack of respect to the others' work is a common problem
in the socialist societies.

4.1.2)

The second main reason is the wide-spread practice of software
pirating (which was, in fact, a kind of state policy) and the very
low payment of the average programmers.

As was mentioned above, Bulgaria took the wrong decision in producing
computers and stealing programs. There is still no copyright law,
concerning computer software there. Because of this, the software
piracy was an extremely widespread practice. In fact, almost all
software products used were illegal copies. Most people using them
have never seen the original diskettes or original documentation.
Very often there was no documentation at all.

Since all kinds of programs (from games to desktop publishing
systems) were copied very often, this greatly helped for the spread
of computer viruses.

At the same time, the work of the average programmer was evaluated
very low - there were almost no chances to sell his/her software
products. Even now, a programmer in Bulgaria is paid 100 to 120 times
less than the programmer with the same qualification in the USA.

This caused several young people to become embittered against the
society that was unable to evaluate them as it should. There is only
one step in the transformation of these young people into creators of
destructive viruses. Some of them (e.g., the Dark Avenger) took this
step.

4.1.3)

The third major reason is the total lack of legislative against
creation and willful distribution of computer viruses and against
illegal access and modification of computer information in general.

Because of the lack of copyright laws on computer software, there is
no such thing as ownership of computer information in Bulgaria.
Therefore, the modification or even the destruction of computer
information is not considered a crime - since no one's property is
damaged.

The Bulgarian legislature is hopelessly old in this area.
Furthermore, even if the appropriate law is accepted in the future,
as a punishing law it will not be able to be applied to crimes,
committed before it was passed. Therefore, the virus writers still
have nothing to fear of.

That is why, the creation of new computer viruses has become some
kind of sport or entertainment in Bulgaria.

4.1.4)

The next reason is the very weak organization of the fight against
computer viruses in Bulgaria. Just now our country is in a very deep
economical crisis. We lack funds for everything, including such basic
goods as food and gasoline. At the same time, the organization of the
virus fight would require money - for the establishment of a
network of virus test centers that collect and investigate computer
viruses, centers equipped with the best hardware, centers that are
able to communicate between themselves and with the other similar
centers in the world in an effective way. Such an effective way is
the electronic mail system - and Bulgaria still does its first
steps in global computer communications. All this requires a lot of
money - money that our government just does not have now.

4.1.5)

Another reason is the incorrect opinion, that the society has on the
computer virus problem.

Still, the victims of a computer virus attack consider themselves as
victims of a bad joke, not as victims of a crime.

4.1.6)

The least important reason, in my opinion, is the availability and
the easy access to information of a particular kind.

All kind of tricks how to fool the operating system circulate among
the Bulgarian hackers. Some of them are often published in the
computer related magazines. As it was mentioned above, there is even
a specialized BBS, dedicated to virus spreading and a special (local
to Bulgaria) FidoNet echo, dedicated to virus writing. Not to mention
the well-known file INTERxyy, published by Ralf Brown from the USA
as shareware. It is very popular in Bulgaria, since it contains,
carefully described, a huge number of undocumented tricks.

However, this is not a very important reason. Usually those, who have
decided to make a virus already know how to do it, or, at least, can
figure it out by themselves. They do not need to take an existing
virus and to modify it. The proof is the prevalence of original
Bulgarian viruses over the variants of known ones, as well as the
fact, that many new ideas for virus writing were first invented and
implemented in Bulgaria.

4.2) General reasons.
----

Since viruses are also created in all the other parts of the world,
there should be also some general reasons for this. These reasons
are, of course, valid for Bulgaria too. Let's see these general
reasons.

4.2.1) Wish for glory.

Every programmer dreams that his/her program gets widely spread and
used. A lot of very good programmers write and distribute wonderful
software packages for free - with the only intention to have more
users using their package. However, for a program to be used, it has
to be good enough. And not every programmer is able to make a program
so good that the users will widely use it - even for free. At the
same time, computer viruses do spread very widely, regardless and
even against the users' will. So, when a virus writer reads in a
newspaper that his virus has been discovered at the other end of the
world, he feels some kind of perverted pleasure. Some people write
viruses just to see their names (or the names of their viruses)
published in the newspapers. This reason has yet another aspect. In
the beginning of the virus era, when the idea of the computer virus
was very new, only the very good programmers were able to make a
virus. It became a common myth that if you can write a virus, you're
a great programmer. This myth might have been justified at the
beginning, but now it is completely without sense. Nevertheless,
young hackers began to write viruses - just to prove to their
friends and to the rest of the world how good programmers they are.
Some of them were really unable to invent something original -
that's why they just picked a known virus, modified it a bit and
released this new mutation. This explains why there are so many
variants of the simplest viruses that were first created - BRAIN,
JERUSALEM, STONED, VIENNA, CASCADE... A typical example is the
Italian virus writer, who calls himself Cracker Jack.

4.2.2) Simple human curiosity.

One has to admit that the idea of a computer program that is able to
spread by its own means, to replicate, to hide from the user (who is
believed to maintain the computer under full control), and in general
to behave as a real live being is really fascinating. Just simple
human curiosity is sufficient to make some people, if they are young
and irresponsible enough, to try to make a computer virus. Some of
them do succeed. A greater and greater part, if we consider the
amount of last reports for new viruses. Some of them claim that they
are writing viruses "only for themselves," "only for fun," and that
"they do not spread them." However, it is often impossible to fully
control the spread of a "successful" computer virus. The more clever
these viruses are, the greater the probability that they will
"escape." There is an idea to teach students how viruses are made -
of course in a very strongly restricted environment. Maybe at least
for some this will fulfil their curiosity and they will not be
tempted to write their own virus. Maybe if we force every computer
science student to learn Dr. Fred Cohen's theorems on the
computational aspects of computer viruses, if we administer an exam
and ask students to design a virus protection scheme or to help a
cluster of users, attacked by a computer virus for a course work -
well, maybe in this case these students will have more than enough of
the computer virus problem and will not want to hear about it any
more - least to make their own viruses.

4.2.3) Easy access to information.

Sufficient information, needed to write a virus can be found easily.
This information is often even more accessible than in Bulgaria.

The person that wants to write an average virus needs only to dig in
the respective manuals - manuals, which are often not available in
Bulgaria. However, the usefulness of the easy access to this
information is much greater than the damage, caused by the fact that
it is used by the virus writers.

4.2.4) Military interests.

It is often rumoured that the superpowers are working on the problem
how to use computer viruses to destroy the enemy computers' software.
It is even very probable, that in several countries such research is
performed. There are reports on this from the USA, France and the
USSR.

This is no wonder - it is the right of every military force to
investigate any new idea and to consider the possible usefulness
and/or threats it might bring to the national defense. However, it is
quite improbable that the computer viruses can be used for this
purpose. Just like the live viruses, the computer ones are able to
spread only among individuals with very similar immunotype, i.e. -
among compatible computers. The most widely used kinds of personal
computers are the IBM PC, Macintosh, Amiga and Atari ST. It is
therefore no wonder that the vast majority of existing computer
viruses are able to infect only these computers. In the same time,
viruses that infect one kind of computer (say, IBM PC), are unable to
spread (or even to run) on another (e.g., a Macintosh). They are
usually not able to run even on two different operating systems in
one and the same computer. Even a different version of the same
operating system might cause big problems to a particular computer
virus - up to preventing it to work. The common personal computers
are never assigned important tasks in the army. Therefore, even if a
virus infects them, and even if it destroys all the data on all such
computers, the caused damage will not be of great importance.
Computers that are used for the really important things, such as
rocket leading or cannon aiming, are always specialized ones. Their
programs are usually hard-coded and only data can be entered in
them. It is not possible to insert an infected IBM PC diskette in the
computers that control the NORAD system. At the same time, the
computers that control different important devices are usually
incompatible even between themselves. Therefore, even if someone
writes a virus for a specialized rocket computer, this virus will not
be able to infect the computers of a strategic bomber or even these
of a rocket of a different system. So, such virus will not spread
very much. And last, but not least, such virus has to be placed
somehow in the enemy's computers. Since, as we saw above, it won't be
able to spread from one computer to another of a different kind,
obviously someone has to insert it in the victim computer. But if you
have access to the enemy's computers, you don't need a virus. You can
do the same task easier (and often much better) "manually", or with a
Trojan horse or a logic bomb.

4.2.5) Corporate interests.

It is also often speculated that the large software companies and the
producers of anti-virus software make or willfully spread computer
viruses.

There is some reason behind this. Indeed the fear of viruses can make
the user buy only original software (sometimes - quite expensive),
and not to use pirated copies, shareware or freeware. At the same
time, companies that produce anti-virus software are interested that
their products are sold. And they will be, if the user needs
anti-virus protection. However, it is rather improbable, that a
software company (whether producing or not anti-virus software) will
take the risk to become known that it willfully spreads viruses. It
will be probably boycotted by its users and the losses of income will
be much greater than any gains. As to the producers of anti-virus
software, they don't need to write viruses themselves, in order to
sell their programs. It is sufficient to use the hype that the media
accords to the problem, to mention how many viruses there are and how
many of them their wonderful product is able to defeat.

5) The Soviet virus factory and virus writing in the other countries
=====================================================================
of the former Eastern block.
============================

While Bulgaria was one of the best computerized countries in East
Europe, the political, economical, and social conditions in the other
countries were (and maybe still are) quite similar. That is why the
virus writing and spreading has been developed in these countries
too.

Viruses are created in Poland ( W13, 217, 583, FATHER CHRISTMAS, DOT
EATER, JOKER, VCOMM, AKUKU, 311, HYBRYD), in Hungary ( STONE `90,
FILLER, MONXLA, POLIMER, TURBO KUKAC), in Czechoslovakia (the
AANTIVIRUS virus), and even in Yugoslavia ( 17Y4, SVIR). According to
some reports from Romania, there are no viruses written there, but
the W13, YANKEE DOODLE, DARK AVENGER and StONED viruses are quite
widespread.

However, the country most similar to Bulgaria is, undoubtedly, the
Soviet Union. According to the Soviet anti-virus researcher Bezrukov
[Bezrukov], the first virus appeared there almost at the same time as
in Bulgaria and, by the way, it was the same virus ( VIENNA). So, the
preconditions are almost the same as with our country.

There are, however, two main differences: the level of
computerization and the number of virus writers.

The level of computerization is still much lower than in Bulgaria.
There are much fewer computers per person than in our country. The
users are much more isolated, due to the much larger distances. The
telephone network is in the same miserable condition, as in Bulgaria.
The networks are very few and not widely used. For instance, in Sofia
alone there are more FidoNet nodes than in the whole Soviet Union. It
is not safe to send floppy disks by regular mail, since they will be
probably stolen. All this delays very much the spreading of viruses.
Unfortunately, it also delays the distribution of anti-virus
products and the information exchange between the anti-virus
researchers. For instance, examples of new viruses created there
reach the Western anti-virus researchers with huge delays.
Unfortunately, the other factor is much more dangerous. In the USSR
there are much more programmers than in Bulgaria and they seem at
least as much motivated in creating new viruses. The virus writing in
the Soviet Union is currently in the same state as it was in Bulgaria
about three years ago. However, at that time only nine variants of
known viruses and one stupid original virus has been created there (6
VIENNA variants, 3 AMSTRAD variants, and the OLD YANKEE virus). At
the first Soviet anti-virus conference in Kiev (mid-November, 1990)
more than 35 different viruses of Russian origin were reported.

Some of them were variants of known viruses, while others were
completely new. It has been noticed that the Soviet virus writers are
less qualified than the Bulgarian ones, but they use a destructive
payload in their creations much more often.

Since the reasons of virus writing in the USSR are very similar to
those in Bulgaria; since this virus writing occurs in a much larger
scale; and since no steps are taken by the authorities in order to
stop it, it is possible to predict that in the next few years the
Soviet Union will be far ahead of Bulgaria in computer virus creation
and that a new, much larger wave of computer viruses will come from
there. Probably after a year, several (up to ten) virus writers with
the qualification of the Dark Avenger will emerge from there.

6) The impact of the Bulgarian viruses on the West and on the national
======================================================================
software industry.
==================

While a huge part of the existing viruses are
produced in Bulgaria, a relatively very small part of them spread
successfully to the West. Of more than 160 Bulgarian viruses, only
very few ( DARK AVENGER, V2000, V2100, PHOENIX, DIAMOND,
NOMENKLATURA, VACSINA, YANKEE DOODLE) are relatively widespread. At
the same time some of them ( DARK AVENGER, V2000, YANKEE DOODLE,
VACSINA) are extremely widespread. According to John McAfee, about 10
% of all infections in the USA are caused by Bulgarian viruses -
usually by the DARK AVENGER virus. In West Europe this virus shares
the popularity with YANKEE DOODLE and VACSINA.

Of the viruses listed above, the major part are written by the Dark
Avenger - all except YANKEE DOODLE and VACSINA. Almost all his
viruses (in this case - with the exception of DIAMOND, which is the
least spread) are extremely destructive. The PHOENIX and NOMENKLATURA
viruses corrupt the FAT in such a subtle way, that when the user
notices the damage, there is no way to disinfect the infected files
and even to determine which files are damaged. The only way is to
reformat the hard disk.

It is difficult to estimate the costs of all damage caused by
Bulgarian viruses. There are reports from Germany about a 10,000,000
DM damage, caused only by the VACSINA virus. It is probable, however,
that these numbers are largely overestimated.

The huge number of known Bulgarian viruses causes also indirect
damage to the West community, even if the viruses themselves do not
escape from Bulgaria, but only examples of them are supplied to the
anti-virus researchers. These researchers have to develop
anti-virus programs against these viruses (just in case the latter
succeed to spread outside Bulgaria). Therefore, they have to waste
their time and efforts. Furthermore, the user is forced to buy new
anti-virus programs (or pay for updates of the old ones), in order
to feel safe against these viruses. In the same time, the creation
and spreading of Bulgarian viruses causes a lot of damage to the
Bulgarian economics. In Bulgaria, the Bulgarian viruses are much more
widespread. More than 80 % of about 160 known Bulgarian viruses have
been detected in the wild in our country. It is difficult, however,
to evaluate, or even to estimate the exact costs of the caused
damage, since in Bulgaria the term "property of computer information"
simply does not exist in legal sense. It is the same with the cost of
this information. In fact, the creation of computer viruses causes
also indirect damage to our economics. First of all, a lot of
extremely capable people are wasting their minds to create
destructive viruses, instead of something useful. Second, the fact
that the Bulgarian programmers use their time to create computer
viruses destroys their reputation as a whole. No serious software
company accepts to deal with Bulgarian programmers or software
companies, because it is afraid that the supplied software might be
pirated or might contain a virus. 7) Conclusion. Virus writing in
Bulgaria is an extremely widespread hobby. Most of the major virus
writers are known, but no measures can be taken against them. Their
work causes a lot of damage to the Western community, as well as to
the national economics. Therefore, it is urgent to take legal
measures in this direction; measures that will make virus writing and
willful spread of computer viruses a criminal act. This is the only
way to stop, or at least to reduce the threat.

References
==========

[KV88] Viruses in Memory, Komputar za vas, 4-5, 1988, pp.12-13 (in
Bulgarian)

[KV89] The Truth about Computer Viruses, Vesselin Bontchev, Komputar
za vas, 1-2, 1989, pp. 5-6 (in Bulgarian)

[Chip] Die neue Gefahr - Computerviren, Steffen Wernery, Chip, 9,
1987, pp. 34-37 (in German)

[Bezrukov] Computer Virology, Nikolay Nikolaevitch Bezrukov, Kiev,
1991, ISBN 5-88500-931-X (in Russian)