| There are different types of computer viruses, | | | | infective module. The seeker module is responsible |
| depending on the nature of the executable | | | | for finding individual files to infect. When such files |
| program and what the rogue programs actually | | | | are found in the infected host system, the |
| do when they begin infecting a host system. | | | | infective module is activated next to infect that |
| Differentiating viruses and spyware | | | | file. |
| Technically, spyware, malware and adware are | | | | Resident viruses on the other hand, have not |
| not types of computer viruses. There is often | | | | been created with seeker modules. Instead, these |
| confusion here; most users call all undesirable | | | | viruses have been designed to load whenever the |
| programs viruses. However, for the sake of | | | | system does. It waits, like a hunter, in the |
| technical clarity, we must correct this. | | | | background until target file types are activated by |
| Computer viruses, like their biological counterparts, | | | | the user. |
| are known for their self-replicating capability. This | | | | Fast-infectors and slow-infectors |
| means the virus can spread from one system (a | | | | Resident viruses are further categorized based on |
| system is your personal computer, laptop, etc.) to | | | | specific actions of the programs within the host |
| other systems. | | | | system. Fast-infecting resident viruses tend to |
| Back in the nineties, MS-DOS viruses and | | | | infect each file that has been activated or used in |
| BIOS-infecting viruses often spread from | | | | the system (you can imagine what this kind of |
| unchecked floppy disks that passed from one | | | | virus can do to a school computer system). |
| user to another (and consequently, one computer | | | | Fast-infecting resident viruses are lethal to |
| to another). | | | | low-grade antivirus programs. If the antivirus |
| Many of these viruses wiped out vital documents | | | | program does not use heuristic methods to trace |
| and other system files. Some of these MS-DOS | | | | potential viruses, the fast-infecting resident viruses |
| viruses were considered as "joke viruses" | | | | can "ride" on the scanner program and infect each |
| because they tend to deactivate after one | | | | file that the antivirus program scans. |
| appearance. However, the same cannot be said | | | | The polar opposite of fast-infecting resident |
| of computer viruses today. | | | | viruses is slow-infecting resident viruses. These |
| Mode of infection | | | | viruses tend to avoid detection by activating only |
| As we have mentioned before, there are varying | | | | with specific actions (like file transfers). Since the |
| types of computer viruses based on what these | | | | mode of infection of slow-infecting resident |
| programs do. A non-resident virus is the simplest | | | | viruses is limited, many anti-virus suites find the |
| type; it's composed of a seeker module and an | | | | offending virus before it can cause any real harm. |