Computer viruses are man-made programs or pieces of code that get loaded into your computer and run without your permission. A common virus makes copies of it again and again till it uses up all the memory and slows down the system or brings it to a total halt. Though there are few harmless computer viruses, the malicious ones are common. They will destroy data, spread from one device to another through network or USB devices and often attempt stealthy tactics to prevent detection by antivirus.
The Family of Computer Viruses
There are several other malware like worms, Trojans, adware, spyware, ransomware and bots that we will cover on different posts. However in this post, Norton technical support UK brings you a glimpse of the different viruses that plague your PC, laptop and mobile security.
Types of viruses
- File infecting viruses – The most common type of virus, it mostly infects files that have .com or .exe extensions. Once the infected file is accessed, the virus will overwrite it partially or completely. It can spread and infect other systems in the network and some can even reformat a hard drive.
- Macro viruses–A macro virus is written in a programming language that remains embedded in a software application. Some of these applications allow macros to run automatically when a document is opened. This gives macro viruses a way to spread.Spreading through email attachments, networks, removable media and internet, it will often replace normal macros with a virus in their place. Being application based, it can run on any operating system.
- Master boot record viruses – Bootkits, programs that can alter the Master Boot Record that contain location of all the partitions in a hard drive, were once popular, spreading viruses through floppies. Now their advanced versions are back and once installed, can disable all security software immediately. Norton support helps Norton antivirus users scan your computers and laptops to find out the possible threats and viruses.
- Boot sector viruses – A disk seeks the MBR when it is first read. Then it gives control to the boot sector which provides relevant information about what is located in the disk and its location. A boot sector virus commonly spreads through a CD, DVD or pen drive, if user has mistakenly left media in a drive.When the system is turned on next, the virus immediately loads and runs like a part of the MBR. It can even spread through email attachments and use the user’s contact lists to spread it across to all her contacts.
- Multi-partite viruses–There were file viruses or boot infectors. Then came viruses with PC BIOS boot sector virus code and DOS executable files, where both parts are infected. These multi-partite viruses spread in multiple ways. And thanks to their multiple vectors, they are super fast.
- Polymorphic viruses – Here the original algorithm remains intact when the polymorphic codes change. They aim to fool the virus scanning program and it often succeeds, as each copy looks different from the others.
Code encryption, used to secure data, is ironically a common method to carry out polymorphism. Some code is left for the decryption that runs the rest. Your antivirus will generally target this code to detect and get rid of the virus.
Stealth viruses – Hiding itself from antivirus software stealthily once the system is infected, it makes the computer look like the file size is not changed or no memory is lost. They count on infecting the boot sector or some system file before the antivirus is installed. Once detected, a scanner removes them easily enough.
Our Norton Support UK helps you install and update the Norton antivirus, resolving any errors that may arise in the process, bringing you the ultimate protection against the different kinds of viruses and other malware.
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