What is a computer virus?
A computer virus is malicious software or code that destroys a device or network. Malicious code could damage the local file system, steal data, interrupt services, or download new viruses. Many viruses pose as legitimate apps to deceive users into using them, delivering the viral payload.
What is a computer virus?
A computer virus is a piece of bad code that is made to spread from one computer to another. Self-copying threats are a type of malware that are usually made to damage a device or steal data.
Think about a biological virus, the kind that makes you sick. It’s always bad, stops you from doing normal things, and often needs something strong to get rid of. A computer virus is also a lot like this. Computer viruses are made to copy themselves over and over again. They can damage your programs and files, change how your computer works, or stop it from working at all.
When a user opens an email attachment, runs an executable file, visits an infected website, or looks at an infected website ad, which is called “malvertising,” the virus can spread. It can also spread through removable storage devices like USB drives that have been infected. Once a virus has infected the host, it can spread to other system software or resources, change or disable core functions or applications, and copy, delete, or encrypt data. Some viruses start spreading as soon as they infect the host, while others stay dormant until a certain event makes the device or system run the malicious code.
Many viruses also have ways to hide from antivirus and antimalware software and other security measures. This is called “evasion” or “obfuscation.” Polymorphic malware, which can change its code as it spreads, is becoming more common. This makes it harder to find and identify viruses.
How does a virus get into a computer?
Viruses can spread in a number of ways, such as through networks, discs, email attachments, and USB sticks. Before, there weren’t as many ways for devices to talk to each other as there are now. As a result, early computer viruses were often spread by infected floppy discs.
Links between devices that can connect to the internet are common today, which makes it easy for viruses to spread. The most common way for computer viruses to spread, according to the U.S. Cybersecurity and Infrastructure Security Agency, is through email attachments that have been hacked. Most computer viruses, but not all, need the user to do something, like turn on “macros” or click a link, for them to spread.
- Even if you are careful, you can get a computer virus by doing things like:
- Users can share music, files, or photos with each other
- Visiting a website with a virus
- Opening a spam email or an attachment in an email
- Free games, toolbars, media players, and other system tools can be downloaded.
- Installing widely used software without carefully reading the licence agreement
What does a computer virus do?
Some computer viruses are made to hurt your computer by breaking programs, deleting files, or reformatting the hard drive. Others just copy themselves or send too much traffic through a network, making it impossible to do anything on the internet. Even less dangerous computer viruses can slow down your system’s performance by using up a lot of memory and causing it to crash often.
Are you ready for the attacks today? In our annual Threat Report, you can find out about the biggest cyber threats of the year.
In 2013, it was found that the botnet virus Gameover ZueS used peer-to-peer downloading sites to spread ransomware and steal money from banks. Even though there are still tens of thousands of computer viruses on the internet, they have changed their ways and are now joined by worms, Trojans, and ransomware.
How to tell if your computer has a virus
Most likely, a computer virus will hurt the device it is on, and you may be able to tell by looking for common signs of performance loss, such as:
How Fast Things Work
One of the most common signs that a computer has a virus is that it runs more slowly than usual. This means that both the system itself and the speed of applications and the internet will slow down. If a computer doesn’t have any powerful programs or applications on it and it’s running slowly, that could mean it has a virus.
Programs that run themselves
If computer programs close on their own without being told to, it’s likely that they have been infected with a virus or other malware. Another sign of a virus is when programs won’t load when you click on them from the Start menu or their icon on the desktop.
Logging out of accounts
Some viruses are made to mess with certain programs, which will either cause them to crash or log the user out of the service automatically.
The Machine Breaking Down
Common signs of a virus are system crashes and the computer shutting down by itself. Computer viruses make computers act in strange ways. For example, they might open files on their own, show strange error messages, or click keys at random.
Your email account is sending out a lot of emails at once
Email is often used to spread computer viruses. Hackers can use the email accounts of other people to spread malware and do larger cyberattacks. So, if there are emails in the outbox of an email account that the user didn’t send, this could be a sign of a computer virus.
Alterations to Your Homepage
Changes that don’t make sense on a computer, like the homepage being changed or browser settings being changed, are signs that a virus may be on the device.
Types of Computer Viruses
Every virus has something called a “payload” that does something. The threat actor can program the virus payload to do any kind of bad thing, even harmless jokes that don’t hurt anyone. Some viruses have payloads that are safe, but most of them hurt the system and the data on it. There are nine main types of viruses. Some of them could be bundled with other types of malware to make them more likely to spread and cause damage. There are nine main types of viruses, which are:
Virus in Boot Sector
Your computer’s hard drive has a sector whose only job is to point to the operating system so that the interface can load. A boot sector virus hurts or takes over the drive’s boot sector, making the machine useless. Most of the time, this type of virus is spread by an infected USB device. The virus starts when the user plugs the USB device into their computer and turns it on.
Virus of Web Scripting
Most browsers have protections against malicious web scripts, but older browsers that are no longer supported have holes that an attacker could use to run code on the local device.
A virus that can change your browser’s settings will take over your favorites, home page URL, and search settings and send you to a bad site. The site could be a phishing page or an adware page that the attacker uses to steal information or make money.
A resident virus is one that can get into computer memory and wait until a payload is sent before doing anything. This malware may stay inactive until a certain date or time, or until a user does something.
Virus with Direct Action
Direct action viruses send a payload right away when a user runs a file that looks harmless but has malicious code attached to it. These viruses can also sleep until a certain action is taken or a certain amount of time has passed.
People who make malware can use code that changes the program’s “footprint” to keep it from being found. When a virus changes, it makes it harder for an antivirus program to find it and get rid of it.
File Infector Virus
A threat actor stays on a system by putting malicious code into critical files that run the operating system or important programs. This is done with file infector viruses. The virus is turned on when the system starts up or when the program runs.
These bad programs spread across a network or other systems by copying themselves or putting code into important computer resources.
Macro programs can be run from Microsoft Office files, and these programs can be used to download more malware or run malicious code. When a file is opened and the macro runs, a macro virus sends a payload.
How do viruses get into a computer?
Not everything has to do with how viruses spread. Once a virus gets a foothold on a system that has just been infected, it starts doing whatever the person who made the virus wanted it to do. This is the process of getting the virus’s payload to the target system. Depending on how the virus works and what permissions the user who made the infection had, it may be able to do whatever it wants on the target system. This is one of the main reasons why security experts advise organisations to follow the principle of least privilege (POLP) and not give users administrative rights on their own systems. This kind of access can make a virus do more damage.
One or more of the three main principles of cybersecurity may be broken by a virus’s payload: confidentiality, integrity, and availability (CIA triad). Confidentiality attacks try to find private information on the target system and send it to the person doing the attack. For example, a virus could search the local hard drive (HD) for Social Security numbers, credit card numbers, and passwords and then send them back to the attacker. Integrity attacks try to change or delete information that is stored on the system without permission. For example, a virus could delete files on a system or make changes to the OS that aren’t supposed to be there. This would help it stay hidden. Availability attacks try to stop the real user from using the system or getting to the information it has. For example, ransomware is a type of virus that encrypts information on the user’s HD, making it impossible for a real person to get to it. Then, it asks for a ransom in exchange for the key to decrypt the file.
A virus could also add a computer to a botnet, giving the attacker control over it. Systems that are part of botnets are often used to attack websites and other systems with distributed denial of service (DDoS) attacks.
How do you keep computers from getting viruses?
You can avoid getting a virus by taking the following steps:
- Install antivirus and antispyware software that is up to date and keep it that way.
- Run scans of your antivirus software every day.
- Turning off autorun will stop viruses from spreading to any connected media.
- Update the computer’s operating system and programs on a regular basis.
- Don’t click on web links that come in emails from people you don’t know.
- Don’t get files or emails from people you don’t know from the internet.
- Install a firewall made of hardware.
How do you remove a computer virus?
If you get a virus on your personal computer (PC), you can get rid of it by doing the following:
- Enter Safe Mode. How to do it will depend on what version of Windows you have.
- Get rid of any temporary files. Use the Disk Cleanup tool while in Safe Mode to get rid of temporary files.
- Download a virus scanner that works both on demand and in real time.
- The on-demand scanner should be run first, then the real-time scanner. If neither virus scanner can get rid of
The virus, it might have to be done by hand. This is something that should only be done by a professional who knows how to use Windows Registry and can see and delete system and program files.
Fix any files or programs that the virus broke.