In short, a virus is just one type of malware. To understand this better, you need to know the difference between virus and malware infections in computing.
When people talk about polymorphic viruses, they often mean polymorphic malware.
For a movie example, think of a polymorphic virus as the T-1000 from Terminator 2, shapeshifting to hide its identity while never losing its core function.
The polymorphic engine, also known as a mutation engine, modifies the malware’s decryption procedure every time it replicates, making its new state challenging for conventional antivirus software to identify. Where polymorphic viruses step up their game is that they employ a polymorphic engine to hide their code, usually through cryptography. All viruses, polymorphic or regular, require host programs, user action to move between systems, and either attach pieces of their malicious code on host files or replace them entirely with malicious copies. Like a regular computer virus, a polymorphic virus corrupts data and slows down system resources, sometimes leading to computer malfunctions like blue screen errors. The difference between a mutating biological virus and a polymorphic PC virus is that the former mutates naturally while someone programs the latter with polymorphism. Similarly, polymorphic viruses mutate to change their code while usually retaining their core function. Think of how frequently the influenza virus mutates or the growing number of novel coronavirus variants - the alterations sometimes help the diseases evade biological defenses. Both types of viruses can also manipulate and corrupt their host’s code to make copies of themselves.Ī subset of computer viruses called polymorphic viruses carries another characteristic from their biological counterpart's arsenal: mutation. While biological viruses invade cells to survive and propagate, computer viruses piggyback on files in a computer’s system to thrive and spread. There are several similarities between biological viruses and computer viruses.