The term malicious software is a name given to a type of software that is designed to disrupt the normal operation of a computer without the consent of the user. (it is abbreviated as malware).
- Malware are capable of installing, corrupting of even deleting other software files.
- Malware doesn’t cover spontaneously; they are created by created by computer programmers and they are designed to do what the programmers designed them to do.
- Malware may be written to amuse people, cause acts of vandalism, attack the products of specific companies and even distribute political messages without the knowledge or intervention of computer users.
- Malware codes can be detected and eliminated from computer systems by means of special types of package called antivirus software.
- Based on function or behavior, malware may be categorized as computer virus, computer worms, trojans horses, spyware, logic bombs, backdoor etc.
- Computer Viruses:
A computer virus is a type of self-replicating malicious program that spreads by inserting copies of itself into other computer files.
- A computer virus behaves in a similar way to a biological virus which spreads by inserting itself into living cells.
- Some viruses are programmed to cause great harm to the computer e.g. damaging programs, deleting files or reformatting the hard disk.
- Others are not designed to do any damage but simply replicate themselves in the computer system.
- Viruses can be classified as program virus (infecting program files e.g. .com or .exe) boot sector virus (infecting boot sectors) multipartite virus (infecting boot sectors and program files), virus hoax (a false warning about computer virus which can arrive by e-mail note or pop-up and clicking on it can get the virus.
Symptoms of computer virus
- You can have warning signs that can be perceived when computer has a virus
- One may encounter strange messages, images, noise or music on the computer
- A computer may be slow and have less memory available
- Files may not open, be deleted, be corrupted or may be shortcut
- Cause the operating system to crash occasionally while others prevent booting of the computer.
General characteristics of a computer virus
- Replication: Typical viruses usually make several copies of themselves after infecting a system
- Polymorphism: This is the ability of a virus to change its own code segments to avoid identification by a virus scanner.
- Versatility: Ability of the virus to attack a wide range of applications software
- Small size: Makes it able to attach itself to other programs and remain unnoticed for a long period of time.
- Tunneling: Some virus has the ability to prevent the correct use of the antivirus package.
Ways to protect your device from computer viruses
- Install a powerful antivirus programs on your computer and make sure it is regularly updated
- Always scan every storage medium from another computer before opening the files on it.
- Use only software from legitimate sources
- Scan every e-mail attachment before opening it
- Do not run suspicious programs
- Educate yourself regularly on computer security issue
- A computer worm is a self-replicating malicious program that spreads from one computer to the next via a network with the purpose of changing or destroying files on the network computers
- Worms do not need to attach itself to other files or program in order to replicate or propagate
- The process of worms is making several copies of themselves, reduce the bandwidth of computer networks on which the worms find itself.
A trojan horse is a malware that disguises itself as a useful and harmless program but contains a hidden virus or worm that can damage the computer on which the trojan horse is run. E.g., you may download an internet game or a picture thinking it is harmless but once you run it, the worm or virus get to work and cause harm to your machine.
- Trojan horse may be used to locate password information or make the system vulnerable to future entry or simply destroy programs or data on the hard disk.
- Trojan cannot operate automatically in contract to some other types of malware e.g., worms.
- Trojan have the ability to erase or overwrite data on a computer, corrupt files, upload and download files, allow remote access to the victim’s computer, spread other malware such viruses and install backdoor on a computer
- A logic bomb is a type of malware program that lies dormant in a system until specific conditions (such as time) are met before it can start acting.
- Logic bomb often enter a computer system by a trojan horse method, but differ because their presence is detected only after the bomb blows up.
This is a type of malware that is installed on computers to monitor and collect information about the user’s activities without the users knowledge.
- All possible personal data are usually gathered and then sent to the author of the spyware.
- This are small programs that are installed on a computer in order to invisibly record all keyboard input.
- Keylogger may either store or record key strokes for later retrieval or they may transmit them to the remote process or person employing the keylogger
This is a form of crypto malware the threatens to publish the victim’s data or permanently block access to it unless a ransom is paid