Polymorphic Viruses

To confound virus scanning programs, virus writers created polymorphic viruses. These viruses are more difficult to detect by scanning because each … [Read more...]

How Viruses Infect

Viruses are sometimes also categorized by how they infect. These categorizations often overlap the categories above and may even be included in the … [Read more...]

Source Code

While rare, it is possible to infect actual programming source code found on your computer. Source code comes in many forms because of the many … [Read more...]

Visual Basic Files

The exploit popular earlier were Visual Basic Script (VBS) worms. What is VBS? Let's see what Microsoft says: Microsoft® Visual Basic® … [Read more...]


Early computers used cathode ray tubes (CRTs) for display. These were basically analog TV sets designed to work with a computer video system. The CRT … [Read more...]


Operating systems and programs are complicated pieces of software with up to millions of lines of source code going into their development. While it … [Read more...]

Batch Files

While not often found, it is possible to write a batch file that contains a virus. In most cases the batch file is used to drop a memory or disk virus … [Read more...]


As indicated throughout this tutorial, in order for a virus to do anything, first a program of some type must execute. A virus, no matter what type, … [Read more...]

Companion Files

Would you believe that a virus can infect your files without changing a single byte in the infected file? Well, it's true; two different ways in fact! … [Read more...]

Directories (Cluster) Viruses

There is a type of virus known as a "cluster" virus that infects your files not by changing the file or planting extra files but by changing the DOS … [Read more...]