The evolution of PC Virus 1

This article provides an overview of methods used to detect malicious code; of the functional (and to some extent chronological) connections between these methods; and of their technological and applied features. Many of the technologies and principles covered in this article are still current today, not only in the antivirus world, but also in the wider context of computer security systems. However, some of the technologies used by the antivirus industry – such as unpacking packed programs and streaming signature detection – are beyond the scope of this article.
The first malware detection technology was based on signatures: segments of code that act as unique identifiers for individual malicious programs. As viruses have evolved, the technologies used to detect them have also become more complex. Advanced technologies (heuristics and behaviour analyzers) can collectively be referred to as ‘nonsignature’ detection methods.
Although the title of this article implies that the entire spectrum of malware detection technologies is covered, it primarily focuses on nonsignature technologies; this is because signatures are primitive and repetitive and there is little to discuss. Furthermore, while signature scanning is widely understood, most users do not have a solid understanding of nonsignature technologies. This article explains the meanings of terms such as "heuristic," "proactive detection," "behavioral detection" and "HIPS", examines how these technologies relate to each another and their advantages and drawbacks. This article, like our previously published The evolution of self-defense technologies in malware, aims to systemize and objectively examine certain issues relating to malicious code and defending systems against malicious programs. Articles in this series are designed for readers who have a basic understanding of antivirus technologies, but who are not experts in the field.