You have probably have heard of viruses, Trojan horse and worms. These are all related to different classes of malicious code. But understanding the difference can be a bit confusing.
They all share the primary objective of replication. However, they are distinctly different with respect to the techniques and ways they use their host system requirements to wreak havoc. This difference is defined by the ways they attack the host systems (servers & computers).Viruses have been usually been restricted to personal computers, while worms have gone after multi-user systems.
As we look at the histories of viruses and worms, it can be highlighted by the differences and similarities of these similar looking malicious codes. The characteristics shown by these histories can be used to explain the differences between the environments in which they are found. Viruses and worms have very different functions. The serve different roles when creating an attack.
Personal computers and multi-tasking workstations narrows as the gap between the differences between a single system that meets all of the requirements necessary to support both worms and viruses. This implies that worms and viruses may begin to appear in new classes of systems. Knowledge of the histories of viruses and worms may make it possible to predict how malicious code will cause problems in the future.
To provide a basis for further discussion, the following definitions will be used throughout the report.
- Trojan Horse: Is a program that performs a useful function, but also performs an unexpected action as well.
- Virus: Is a code segment, which replicates by attaching copies to existing executable application, etc.
- Worm: Is a program, which replicates itself and causes execution of the new copy that looks normal but is its own program that can create havoc.
- Network Worm: Is a worm which copies itself to another system by using common network facilities, and causes execution of a copy on that system that looks like the program but is all about creating havoc.
What is necessary for a virus to go viral?
There are really only four things that are needed for a virus to cause a whole lot of havoc, and they are:
- Requires a host program as a carrier
- Activated by external action
- Replication limited to (virtual) system