What causes a computer virus and what protection can do

Regarding email attachments and embedded links, even if the sender is someone you know: viruses have been known to hijack Outlook contact lists on infected computers and send virus laden attachments to friends, family and coworkers, the Melissa virus being a perfect example. A simple call or text message can save you a lot of trouble.

Next, invest in good cybersecurity software. Antivirus AV refers to early forms of cybersecurity software focused on stopping computer viruses. Just viruses. Given a choice between traditional AV with limited threat detection technology and modern anti-malware with all the bells and whistles, invest in anti-malware and rest easy at night. As mentioned previously in this piece, traditional AV solutions rely on signature-based detection.

AV scans your computer and compares each and every file against a database of known viruses that functions a lot like a criminal database. Going back to our virus analogy one final time—removing a virus from your body requires a healthy immune system.

Same for your computer. A good anti-malware program is like having a healthy immune system. The free version of Malwarebytes is a good place to start if you know or suspect your computer has a virus. Available for Windows and Mac, the free version of Malwarebytes will scan for malware infections and clean them up after the fact.

Get a free premium trial of Malwarebytes for Windows or Malwarebytes for Mac to stop infections before they start. You can also try our Android and iOS apps free to protect your smartphones and tablets. All the tactics and techniques employed by cybercriminals creating modern malware were first seen in early viruses. Things like Trojans, ransomware, and polymorphic code.

These all came from early computer viruses. To understand the threat landscape of today, we need to peer back through time and look at the viruses of yesteryear. Other notable firsts—Elk Cloner was the first virus to spread via detachable storage media it wrote itself to any floppy disk inserted into the computer.

But a Scientific American article let the virus out of the lab. In the piece, author and computer scientist A. Dewdney shared the details of an exciting new computer game of his creation called Core War. In the game, computer programs vie for control of a virtual computer. The game was essentially a battle arena where computer programmers could pit their viral creations against each other. For two dollars Dewdney would send detailed instructions for setting up your own Core War battles within the confines of a virtual computer.

What would happen if a battle program was taken out of the virtual computer and placed on a real computer system? In a follow-up article for Scientific American, Dewdney shared a letter from two Italian readers who were inspired by their experience with Core War to create a real virus on the Apple II. The brainchild of Pakistani brothers and software engineers, Basit and Amjad Farooq, Brain acted like an early form of copyright protection, stopping people from pirating their heart monitoring software.

Other than guilt tripping victims in to paying for their pirated software, Brain had no harmful effects. BHP also has the distinction of being the first stealth virus; that is, a virus that avoids detection by hiding the changes it makes to a target system and its files.

The cover image depicted viruses as cute, googly eyed cartoon insects crawling all over a desktop computer. Up to this point, computer viruses were relatively harmless. Yes, they were annoying, but not destructive. So how did computer viruses go from nuisance threat to system destroying plague? The MacMag virus caused infected Macs to display an onscreen message on March 2, The infected Freehand was then copied and shipped to several thousand customers, making MacMag the first virus spread via legitimate commercial software product.

The Morris worm knocked out more than 6, computers as it spread across the ARPANET , a government operated early version of the Internet restricted to schools and military installations.

The Morris worm was the first known use of a dictionary attack. As the name suggests, a dictionary attack involves taking a list of words and using it to try and guess the username and password combination of a target system. Robert Morris was the first person charged under the newly enacted Computer Fraud and Abuse Act , which made it illegal to mess with government and financial systems, and any computer that contributes to US commerce and communications.

In his defense, Morris never intended his namesake worm to cause so much damage. According to Morris, the worm was designed to test security flaws and estimate the size of the early Internet. A bug caused the worm to infect targeted systems over and over again, with each subsequent infection consuming processing power until the system crashed. Victims received a 5.

Joseph L. Popp, intended to draw parallels between his digital creation and the deadly AIDS virus. A virus operates by inserting or attaching itself to a legitimate program or document that supports macros in order to execute its code. In the process, a virus has the potential to cause unexpected or damaging effects, such as harming the system software by corrupting or destroying data. Once a virus has successfully attached to a program, file, or document, the virus will lie dormant until circumstances cause the computer or device to execute its code.

In order for a virus to infect your computer, you have to run the infected program, which in turn causes the virus code to be executed. This means that a virus can remain dormant on your computer, without showing major signs or symptoms. However, once the virus infects your computer, the virus can infect other computers on the same network. Stealing passwords or data, logging keystrokes, corrupting files, spamming your email contacts, and even taking over your machine are just some of the devastating and irritating things a virus can do.

While some viruses can be playful in intent and effect, others can have profound and damaging effects. This includes erasing data or causing permanent damage to your hard disk. Worse yet, some viruses are designed with financial gains in mind. In a constantly connected world, you can contract a computer virus in many ways, some more obvious than others.

Viruses can be spread through email and text message attachments, Internet file downloads, and social media scam links. Your mobile devices and smartphones can become infected with mobile viruses through shady app downloads. Viruses can hide disguised as attachments of socially shareable content such as funny images, greeting cards, or audio and video files.

This type of virus can take control when you start — or boot — your computer. One way it can spread is by plugging an infected USB drive into your computer. This type of virus exploits the code of web browsers and web pages. If you access such a web page, the virus can infect your computer. A resident virus can execute anytime when an operating system loads. This type of virus comes into action when you execute a file containing a virus. Otherwise, it remains dormant.

A polymorphic virus changes its code each time an infected file is executed. It does this to evade antivirus programs. This common virus inserts malicious code into executable files — files used to perform certain functions or operations on a system.

This kind of virus infects and spreads in multiple ways. It can infect both program files and system sectors. Macro viruses are written in the same macro language used for software applications.

Such viruses spread when you open an infected document, often through email attachments. You can take two approaches to removing a computer virus. One is the manual do-it-yourself approach. The other is by enlisting the help of a reputable antivirus program. Want to do it yourself? There can be a lot of variables when it comes to removing a computer virus. This process usually begins by doing a web search. You may be asked to perform a long list of steps.

If you prefer a simpler approach, you can usually remove a computer virus by using an antivirus software program. These updates can help prevent viruses and other malware attacks by closing possible security holes.

Windows Update helps to make sure that your PC receives these updates automatically, but you may still have to restart your machine occasionally for the updates to install completely. Use your internet browser's privacy settings - Some websites might try to use your personal info for targeted advertising, fraud, and identity theft.

All modern browsers have privacy settings that you can enable to control what sites can see or do. For more information about configuring the privacy settings in Microsoft Edge see Configure your privacy settings so they're right for you.

UAC can help keep viruses from making unwanted changes. To open UAC, swipe in from the right edge of the screen, and then tap Search. If you're using a mouse, point to the upper-right corner of the screen, move the mouse pointer down, and then click Search.

Enter uac in the search box, and then tap or click Change User Account Control settings. Make sure that Tamper Protection is turned on - In Windows 10 and 11 we have a feature called Tamper Protection that prevents unauthorized apps from changing your security settings. Many viruses and malware try to disable anti-malware software or other security settings when they're installed in order to evade detection.

See Prevent changes to security settings with Tamper Protection for information on how to confirm that it's turned on. If you use more than one antivirus or antispyware program at the same time, your PC may experience decreased performance, become unstable, or restart unexpectedly. Caution: When you remove your currently installed Internet security programs, your PC is in an unprotected state. If you haven't installed another antimalware program make sure that Microsoft Defender Antivirus is enabled, and that Windows Firewall is turned on.

Note: Some security software may not uninstall completely. If you're unable to fully uninstall an app, go to the publisher's website or contact their technical support line for help. Windows 10 Windows 8. More isn't always better Running multiple anti-malware apps at the same time can cause your system to be slow or unstable.

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