The term "core virus" isn't a recognized term in the world of computer viruses. Viruses are simply malicious programs that replicate and spread. They are made up of code, typically written in programming languages like C, C++, or assembly.

Here's what a virus typically consists of:

* Code: The actual instructions that tell the computer what to do. This includes the instructions for replication, spreading, and carrying out the virus's malicious purpose.

* Payload: This is the harmful action the virus performs. It could be anything from deleting files to stealing data to taking control of the computer.

* Infection mechanisms: This part of the code determines how the virus spreads, for example, by attaching itself to other files, exploiting vulnerabilities in software, or using social engineering tactics.

Remember: The term "core virus" is not a standard term. If you've encountered it, it's likely a misunderstanding or a term used in a specific context.