A resident virus hides and stores itself within the computer memory, which then allows it to infect any file that is run by the computer, depending on the virus’s programming. It infects other files even when the originally infected program is no longer running.
A resident virus will load its replication module into memory so it does not need to be executed for it to infect other files. Non-resident virus need an executed file.
Being stored in memory allows the virus to spread easier because it has more access to other parts of the computer. It activates whenever the operating system loads or operates a specific function.
This virus is one of the worst viruses as it can even affect the system thoroughly. The resident virus can attach itself to anti-virus applications which allows it to infect any file scanned by the anti-virus.
Resident viruses are sometimes subdivided into a category of fast infectors and a category of slow infectors.
Let us understand what is and what types are computer memory.
Computer memory is just like a human brain. Computer memory is the storage space in the computer, where data is to be processed and instructions required for processing are stored.
Computer memory is of two types, Cache Memory and Main Memory
1.Cache Memory: Cache memory is a very high-speed memory that can speed up the CPU. It acts as a buffer between the CPU and the main memory.
2.Main Memory: This holds only those data and instructions on which the computer is currently working. It is lost when power is switched off.
Main memory is further divided into two parts, RAM (Random Access Memory) and ROM (Read-only Memory)
RAM: It is the hardware in a computing device where the operating system (OS), application programs and data in current use are kept so they can be quickly reached by the device’s processor.RAM is a volatile memory and requires power to keep the data accessible. If the computer is turned off, all data contained in RAM is lost.
ROM: This is a hardware medium in a computer device that permanently stores data on a computer. It contains the programming needed to start a computer, which is essential for boot-up. It performs major input/output tasks and holds programs or software instructions.
Because ROM is read-only, it is permanent and non-volatile and holds its memory even when a computer is turned off.