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Computer Fundamentals - Virus
What is a Virus Computer?
Virus − Computer viruses are programs which interrupt your system, cause major problems with operation and result in loss or leakage of information. These programmes are intended to spread among the various programs and systems. The computer virus usually attaches itself to an executed host file, resulting in its viral code running while the file is opened. The code is then spread using networks, drives, file-sharing programs, or infected email attachments, from the document or software it is attached to.
How do Computer Viruses Spread?
Viruses can be propagated by email and text message attachments, Internet file downloads, social media scam links, and even dubious App downloads, which can infect your mobile devices and smartphones. Viruses can hide as attachments to socially shareable information like amusing photos, greeting cards, or audio and video files.
To avoid coming into contact with a virus, be cautious when surfing the web, downloading data, and opening links or attachments. As a best practice, never download unexpected text email attachments or files from untrustworthy websites.
Identification of Computer Viruses
It's a common question of a human's mind how do we know or identify that a computer virus has entered into their system? There are some common signs which give an alert to the users that a virus has entered the system. These are as −
Fig: Common signs of computer viruses
- Slow Speed − One of the most prevalent indications of viruses in the system is its slow speed. This includes the system running slowly, apps, and internet speed going down. If a system doesn’t have heavy applications and gives slow performance indicates a virus-infected system.
- Pop-up windows − If a computer has unexpected pop-up windows gives a sign of a virus in the system. Hence, unwanted pop-ups are a sign of malware, viruses or spyware affecting the device.
- Programs self-executing − Computer applications that run unexpectedly as automatic opening programs, closing programs or as suddenly appearing on screen give a common sign of being infested with a virus or malware. Applications that won't load from the Start menu or desktop icon are another sign of a virus.
- Missing Files or Programs − If you suddenly lose files or programs on your computer, it may be a sign that malware is deleting or encrypting them.
- Accounts being logged out − Certain viruses are designed to affect specific applications, which may cause them to crash or require users to automatically log out of the service.
- Crashing of the device − A common sign of a virus is a system failure and the computer itself suddenly stopping. Computer viruses are causing computers to behave in several weird ways, such as opening files on their own, displaying special error messages or clicking random key combinations.
- Mass emails being sent from your email account − It's a common virus that spreads using email. It aims to carry out more sophisticated cyber-attacks, steal information, hack a person's email account, and send an email to an outbox that was not sent by the user.
- Changes to your homepage − A sign of a computer virus can be depicted using unforeseen changes to the machine, e.g. your system's homepage being changed or browser settings being adjusted automatically.
- Security Warnings − A user gets security warning alerts about malware infections or other security threats, it's important not to ignore them as it’s a common sign of virus in the system.
- Disabled Security Software − If the antivirus is available on the user's system; it automatically stops its working due to viruses. Security software suddenly disables and stops updating due to malware.
Types of Computer Viruses
Different types of computer viruses can infect computer systems. Some common types are as follows −
- Boot Sector Virus − The Master Boot Record (MBR) of a computer is the target of a boot sector virus. After inserting its code into the partition table of a hard drive, the virus migrates into the main memory when the system restarts. The virus causes poor system performance, difficulties booting up, and the inability to locate the hard disk. Most of the advanced computer systems have built-in security features for Boot sector protections.
- Resident Virus − Viruses spread via infecting software on the host computer. A resident virus accomplishes this by infecting applications when they are opened by a user. A non-resident virus can infect executable files even when no programs are executing.
- Multipartite Virus − A multipartite virus gets into computers and spreads to other components. It will usually stay in the computer's memory to infect the hard drive. It will then change the content of applications to attack more drives. This slows things down and causes program memory to run out. To protect the system from multipartite viruses by not opening attachments received from untrusted sources trusted antivirus software and cleaning the computer's boot area and disk.
- Direct Action − A direct action virus enters a computer's main memory and infects all applications, files, and directories in the autoexec.bat directory before eliminating itself. This virus typically affects system performance, but it is capable of removing all data on the computer's hard drive and any USB device connected to it. Direct-action viruses can be avoided by using antivirus scanners. They are simple to identify, as is recovering contaminated files.
- Browser Hijacker − Generally, this program does not affect files but blocks the browser so users will not be able to restore their homepage or search engine.
- Overwrite Virus − As its name implies, these are viruses which can delete data and replace contents or codes on their own; once files get infected, they cannot be changed or replaced. Overwrite viruses are very powerful even if they can affect operating system files for Windows, DOS, Linux, and Mac systems. This virus can only be erased by removing all the infected files. A user can protect their system by keeping trusted antivirus in their computer.
- Web Scripting Virus − This virus breaches web browser security, and affects web-pages code with malicious. This enables cybercriminals to target prominent websites like social networking sites, email providers, and any other site that accepts user input or reviews. The virus can be used by attackers to send spam, commit fraud, and corrupt server files. A user can protect their system by deploying real-time web browser protection software, cookie security, keep scripts disabled and malicious software removal tools.
- File Infector − It is one of the most common viruses. It overwrites files when they are opened and can quickly spread across systems and networks. It primarily affects files with.exe or.com extensions. Users are advised to use official software and an antivirus solution to protect their system.
- Network Virus − A network virus cripples entire computer networks. These viruses are hidden in infected computers on the network. As the viruses are on the network they spread across multiple devices connected to the network. Setting up a computer network is a very complex process; network viruses are very dangerous for the system because they affect the working of the entire computer network. To protect the system from such kinds of viruses; advanced firewalls and trusted, robust antivirus solutions are required to implement on the entire network.
Frequently Asked Questions / FAQs on Computer Virus
A virus is a specially designed computer program to affects computer file systems by infecting them, and computer networks by spreading viruses over the network, computer devices, and websites by infecting its script code etc.
Generally, viruses are spread through sharing files and accessing portable media like pen drives, and email messages.
A virus is a computer program; that affects a computer system by doing actions programmed into it like a boot sector virus designed to stop or affect the booting process of a computer; a file infector virus deliberately damages files.
A worm is a type of virus; these are spread from device to device and purposely affect systems memory and network bandwidth, which may cause a computer to stop working.
A common difference between a computer virus and a worm is that viruses trigger when a host/victim accesses an infected file while Worms are standalone harmful programmes that may self-replicate and spread once they have entered the system.
A Trojan horse is the name of a computer virus. It is malware that hides on a computer as a legitimate program; it reaches to user's system as an attachment in an email or during a free-to-download file.
You should not open unknown email attachments or deleting untrusted emails. You can also prevent a virus by selecting the option of viewing your email messages in plain text, not HTML.
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