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for an article; for Tedor, it was the catalyst for a new intellectual pursuit.

On 10 November 1988 Teodor sat down at a computer at the technical institute where he worked and started to write his first virus. Two days later, Teodor proudly made an entry in his diary: ‘Version o lives.’

Version o was, in all probability, the first home-grown Bulgarian virus. It did very little except replicate, leaving copies of itself on what are called COM files – simple executable files which are limited in length and used for basic computer utilities. When the virus infected a file it beeped.

Two days after writing Version o, Teodor had prepared Version 2.4 It was cleverer than the original in that it could infect both common types of executable files: COM and EXE. The latter are the more sophisticated programs – like word-processing, for instance – and because they are structurally complex they are more difficult to infect. But Teodor’s Version 2 employed a little trick that would convert the shorter EXE files into COM files. When the operator called up, or loaded, an EXE file, the lurking virus saw the load command, jumped in ahead and modified the structure of the EXE file so it resembled a COM file. The next time a restructured EXE file was loaded up, it could be successfully infected by the virus, just like an ordinary COM file.

Teodor was also experimenting with anti-virus software at the time, and developed a program that would hunt down and kill Versions o and 2. It was called ‘Vacsina’, the Bulgarian word for vaccine. However, by Version 5 Teodor had adapted his virus so that it was immune to his own killer program. He accomplished this by simply adding the character string ‘Vacsina’ to the virus. When his anti-virus program saw the string, it would leave the bug alone.

It was shortly thereafter that Version 5 escaped. Like most Bulgarians, Teodor had to share his computer with colleagues at the Technical Institute; with four people using one machine, with software copying rampant, and with the casual transfer of diskettes, it was only a matter of time before one of the bugs began to propagate out of his control. Within weeks Version 5 had spread throughout Bulgaria. In less than a year it had reached the West – the first

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