In the early, pre-internet days, viruses often spread from computer to computer via infected floppy disks. The SCA virus, for instance, spread amongst Amiga users on disks with pirated software. Today, viruses spread via the internet. In most cases, applications that have been infected by virus code are transferred from computer to computer just like any other application. Because many viruses include a logic bomb — code that ensures that the virus's payload only executes at a specific time or under certain conditions — users or admins may be unaware that their applications are infected and will transfer or install them with impunity.
Infected applications might be emailed inadvertently or deliberately — some viruses actually hijack a computer's mail software to email out copies of themselves ; they could also be downloaded from an infected code repository or compromised app store. One thing you'll notice that all of these infection vectors have in common is that they require the victim to execute the infected application or code.
Remember, a virus can only execute and reproduce if its host application is running! Still, with email such a common malware dispersal method, a question that causes many people anxiety is: Can I get a virus from opening an email?
The answer is that you almost certainly can't simply by opening a message; you have to download and execute an attachment that's been infected with virus code. That's why most security pros are so insistent that you be very careful about executing email attachments, and why most email clients and webmail services include virus scanning features by default.
A particularly sneaky way that a virus can infect a computer is if the infected code runs as JavaScript inside a web browser and manages to exploit security holes to infect programs installed locally. Some email clients will execute HTML and JavaScript code embedded in email messages, so strictly speaking, opening such messages could infect your computer with a virus.
But most email clients and webmail services have built-in security features that would prevent this from happening, so this isn't an infection vector that should be one of your primary fears. Symantec has a good breakdown on the various types of viruses you might encounter , categorized in different ways. We've already met resident and non-resident viruses , boot sector viruses , web scripting viruses , and so on.
There are a couple other types you might want to be aware of:. Keep in mind that these category schemes are based on different aspects of a virus's behavior, and so a virus can fall into more than one category. A resident virus could also be polymorphic, for instance. Antivirus software is the most widely known product in the category of malware protection products. Viruses are designed to spread quickly and easily, and can do so in a number of ways.
The most common are:. What does anti-virus software do? It does this in 2 ways. What should you install? September 25 This means that a virus can remain dormant on your computer, without showing major sings 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 , such as erasing data or causing permanent damage to your hard disk, and worst yet, some are even design with financial gains in mind. Viruses can be spread through email and text message attachments, Internet file downloads, social media scam links, and even 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. As you can see, just like a vicious flu virus, a computer virus is something that you want to avoid. The terms virus and malware are often used interchangeably; however, a virus is one of many types of malware, and only one aspect of the overall threat landscape. 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. For instance, Norton AntiVirus Basic can remove many infections that are on your computer. The product can also help protect you from future threats.
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