[...]... think of viruses as sort of a black art The purpose of this volume is to bring them out of the closet and look at them matter -of- factly, to see them for what they are, technically speaking: computer programs The second volume discusses the scientific applications of computer viruses There is a whole new field of scientific study known as artificial life (AL) research which is opening up as a result of the. .. program to another, we have to dig into the details of how the operating system, DOS, loads a program into memory and passes control to it The virus must be designed so it’s code gets 22 The Little Black Book of Computer Viruses executed, rather than just the program it has attached itself to Only then can it reproduce Then, it must be able to pass control back to the host program, so the host can execute... two willing parties to exchange one Never 8 The Little Black Book of Computer Viruses mind that the Constitution guarantees freedom of speech and freedom of the press Never mind that it guarantees the citizens the right to bear military arms (and viruses might be so classified) While that law has not passed as of this writing, it may by the time you read this book If so, I will say without hesitation... idea of a man actually standing on the moon would have been to Galileo We just have no idea There is something in certain men that simply drives them to explore the unknown When standing at the edge of a vast ocean upon which no ship has ever sailed, it is difficult not to wonder what lies beyond the horizon just because the rulers of the day tell you you’re going to fall of the edge of the world (or they’re... possibilities of these magnificent machines This brotherhood has included famous mathematicians and scientists, as well as thousands of unnamed hobbyists who built their own computers, and programmers who 4 The Little Black Book of Computer Viruses love to dig into the heart of their machines As long as computers have been around, men have dreamed of intelligent machines which would reason, and act... instead of just 16 Such a register pair consists of a segment register, which contains the most significant bits of the address, and an offset register, which contains the least significant bits The segment register points to a 16 byte block of memory, and the offset register tells how many bytes to add to the start of the 16 byte block to locate the desired byte in memory For example, if the ds register... reads the first few bytes of the file into memory, and writes them back out to the file in a special data area within the virus’ code The new virus will need these bytes when it executes 5 Next the virus in memory writes a jump instruction to the beginning of the file it is infecting, which will pass control to the new virus when its host program is executed 6 Then the virus in memory takes the bytes... it an application-specific virus These viruses make use of a detailed knowledge of the files they attack to hide better than would be possible if they were able to infiltrate just any file For example, they might hide in a data area inside the program rather than lengthening the file However, in order to do that, the virus must know where the data area is located in the program, and that differs from... goal of survival and self-reproduction, because they make the fact of the virus’ existence known to everybody If there is just a little more disk activity than expected, no one will probably notice, and the virus will go on its merry way On the other hand, if the screen to one’s favorite program comes up saying “Ha! Gotcha!” and then the whole The Basics of the Computer Virus 18 computer locks up, with... a simulation of a wash machine, complete with graphics and sound Another makes Friday the 13th truly a bad day by coming to life only on that day and destroying data None the less, these kinds of routines are more properly the subject of volume three of this series, which discusses the military applications of computer viruses In this volume we will stick with the basics of designing the reproductive . publication. With the release of The Giant Black Book of Computer Viruses, though, the publisher has decided to take The Little Black Book out of print. They’ve. any viruses one may run across in his 2 The Little Black Book of Computer Viruses day to day computing. Many people think of viruses as sort of a black