When it comes to computer security, a vulnerability is an imperfection that can be exploited by a threat actor. Simply this means an attacker can perform
unauthorized actions within a computer system. To exploit the vulnerability, mostly attackers use some tools or techniques to hack the system’s weaknesses.
Let’s identify what is the malicious software which comes under this,
Malicious software or malware normally includes harmful threats such as computer viruses, worms, and Trojan horses, etc.
A computer virus is a rascal software that attaches itself to other programs or data files in order to be executed, and not only that it may be highly destructive to files, computer memory, and hard drivers also. Viruses are typically designed to spread from computer to computer through e-mail attachments or some external devices like…networks, USB flash drives, or memory disks.
Worms also act as a computer virus. Nevertheless, it can act as independent computer programs that copy themselves to computers over a network independently from other computer programs or files. Mostly use social engineering techniques such as email attachments, fake websites, and instant message frames to add these worms. So that’s why this spread is speedier.
A Trojan horse means once the Greeks had used some kind of woods to subjugate the Troy Kingdom. So using that kind of wood, they have been created a horse. As a result of this, has been taking an example of making this Trojan Horse Software. Also, this is malicious software and normally this performs some hidden action. Such as installing a malicious order or compromising the security of a computer.
Spyware also acts as malicious software by obtaining information about the user’s buying habits and violates privacy. Keyloggers record keystrokes m SQL injection is a type of security exploit in which the attacker adds Structured Query Language (SQL) code to a web form input box to gain access to resources or make changes to data. Further, it requests for some action to be performed on a database.
Ransomware is a subset of malware in which the data on a victim’s computer is locked, typically by encryption and payment is demanded data is decrypted and access returned to the victim. The motive for ransomware attacks is nearly always monetary and unlike the other types of attacks then the victim is often notified that how can recover from that attack.
Adware, the nature of this malicious software to display the presence of unwanted advertising computers and obtain commercial information using those ads. Though unwanted advertising is not harmful rather than computer viruses. Normally, the user will mentally be distressed.
Hijacker / Browser Hijacker is designed for commercial and advertising purposes, misleading the user when he connects to the internet. He also misleads and redirects that link to other web pages. Also, this is similar to the Adware malicious.
Phishing attacks by tricking users into obtaining information on their bank accounts or electronic accounts. Mostly use emails for this task. These articles will be sent to the users as a brand new company or friend’s new link and a link to another website will also be sent by clicking on that link or filling out the detailed form leaflets used to steal users’ money and important information.
Spam means unauthorized emails are called spam. Mostly these emails can be advertisements or e-mails sent by unknown persons. Because of this cause convenience, the users due to overcrowding of postal accounts. Further, e-mails sent by individuals to obtain fraudulent email addressed for fraudulent purposes are also known as spam.
Now, let’s briefly identify what is meant by a computer virus…?
Computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation. A virus might corrupt or delete data on your computer, use your email program to spread itself to other computers, or even erase everything on your hard disk. Viruses are most easily spread by attachments in e-mail messages or instant messaging messages. That is why you must never open email attachments unless you know who it’s from and you are expecting it. Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files. Viruses also spread through downloads on the internet. There can be hidden in illicit software or other files or programs you might download. To help avoid viruses, it’s essential that you keep your computer current with the latest updates and antivirus tools, stay informed about recent threats, and that you follow a few basic rules when you surf the internet, download files, and open attachments. Once a virus is on your computer, its type or the method it used to get there is not as important as removing it and preventing further infection. The term comes from the term virus in biology. A computer virus reproduces by making, possibly, modified, copies of itself in the computer’s memory, storage, or over a network. This is similar to the way a biological virus works
How does a computer virus attack?
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. 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 the virus can remain dormant on your computer, without showing major signs or symptoms. However, once the virus infects your computer, the virus can infect the computers or data, logging network. Stealing passwords or data, logging keystrokes, corrupting files, spamming your email contact, 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 damages to your hard disk. Worse, some viruses are designed with financial gains in mind.
How do computer viruses spread?
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, audio and video files.
To avoid contact with a virus, it’s important to exercise caution. When surfing the web, and downloading files, opening links or attachments to help stay safe, never download text or email attachments that you’re not expecting, or files from websites you don’t trust.
Different Types of Computer Viruses
There are millions of viruses around the world.
- Boot sector virus – 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
- Web scripting virus -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.
- Browser hijacker -This type of virus ‘hijacks’ certain web browser functions and you may be automatically directed to an unintended website
- Resident virus -This is a general term for any virus that inserts itself in a computer system’s memory a resident virus can execute anytime when an operating system loads.
- Direct action virus -This type of virus comes into action when you execute a file containing a virus. Otherwise, it remains dormant.
- Polymorphic virus – A polymorphic virus changes its code each time an infected file is executed. It does that to evade antivirus programs.
- File infector virus -This common virus inserts malicious code into executable files – files used to perform certain functions or operations on a system.
- Multipartite virus – This kind of virus infects and spreads in multiple ways. It can infect both program files and the system sector.
- Macro virus – 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 at attachments.
Examples for Computer Virus
Let’s discuss what are examples of computer viruses.
- Morris Worm -Let us start our journey with Morris Worm or the “Great Worm”, which is believed to be the pioneer among computer worms distributed through the internet. Created to highlight security flaws in UNIX systems, its founder Robert Morris, made a fatal error that transformed the worm from a potentially harmful software to a denial-of-service (DDOS) attack machine.
- Nimda – A worm, a virus, and a Trojan horse all in one sounds like something out of a horror movie. But it’s a computer virus known as Nimda (admin spelled backward) that hit the internet back in 2001.
- ILOVEYOU – Romantic as it sounds, the ILOVEYOU virus is not the kind of a gift you’d want to receive on Valentine’s Day. The virus used emails as a transmission channel, disguising itself as a love letter from one of its victim’s contacts. The malware was hidden in the attachment. The takeaway: be careful when opening strange attachments in a love letter, even if it comes from your love interest.
- SQL Slammer – Outages in 911 service in Seattle, the crash of the Bank of America’s ATM service, and cancellation of several Continental Airlines flights – these are just a few examples of what SQL Slammer (or simply Slammer) is capable of.
- Stuxnet – The destructive power of computer viruses can make them weapons of mass digital destruction, and Stuxnet became the first one. Unlike any other virus or malware of that time, Stuxnet was developed by the US and Israeli government engineers to disrupt Iran’s nuclear program. Spread via a USB thumb drive, it targeted Siemens industrial control systems, causing centrifuges to mysteriously fail and self-destroy at a record rate.
- Tinba – Tinba is the pet name for the Tiny Banker Trojan that hit the headlines in 2016. As the name suggests, its main target was financial institution websites. Tinba used man-in-the-browser attacks and network sniffing to get users’ banking information.
- Welchia – Viruses can also be created to serve ethical purposes. Welchia or the Nachi worm is one of those.
What are the signs of Computer Virus infection?
Unexpected pop-up window
This means a typical sign of virus infection. For instance, never click on a suspicious pop-up even if it says ‘a virus was detected’. Which asks you to pay for a program to remove a fake virus but may allow even more malware to be downloaded.
Slow start-up and slow performance
If your Pc has got down with a virus, then it may be taking too long than normal to start and programs also like that. At that time you should check whether your RAM / hard disk spaces are good or bad. If there are no errors in that, it might be a virus attack.
Suspicious drive activity
An excessively active hard disk where it makes continual noise or constantly spins – even though you’re not using your computer nor have any programs running – can be a sign your PC is infected with a virus.
Lack of storage space
If you suddenly find yourself devoid of storage space on your hard drive, a virus may be doing its utmost to make your computer unusable.
Some malware causes problems by deleting files and programs or moving them around. Some may encrypt your files so you aren’t able to open them.
Crashes and error messages
If programs start opening and closing automatically, your system freezes or shut down for no reason, or you see odd error messages, then you may have a virus.
Email is Hijacked
If your internet connection is very active even when you’re not using it, a virus may be busy sending information back and forth across the internet.
Your web browser becomes sluggish, your home page changing or being redirected to unusual websites are all warning signs of a computer virus infection.
Some viruses are designed to disable your computer’s protection. So, if you can’t open or install an anti-virus program or your firewall, your computer may be infected.
Infected computers are often programmed to respond with an audio signal to things you cannot control. They’ll be things like warning beeps,” Armstrong said. “When an error message pops up, a lot of times, it comes along with a warning message. Certain pieces of malware stifle that window so you can’t see it. But you might still hear the warning message – a sound in the background that you didn’t initiate.”
Unexplained file or folder changes
Your files might be missing, or the icons and content of your files may be different. Your computer won’t make these types of changes to your files unless you have a virus or technical problem.
Random connections to unknown websites
Another sign of an infection is when your legitimate antivirus software alerts you that an application is trying to connect to a website you’ve never heard of. In general, your computer doesn’t make its own connections; someone has to initiate them. If you didn’t initiate these connections, problematic software could be doing it for you.
How to protect your computer from computer virus?
Install as antivirus
There are many antivirus programs available, all ranging in price as the level of security increases. Installing the best antivirus is no easy task, and sometimes it may be safer for us to download more than one if they each cover different security aspects.
Keep your software up to Date
Receive frequent updates that enhance individual features. These updates also include security measures that keep our computers safe from the latest batch of viruses and malware cooked up by hackers.
Backup Your Computer
Sometimes we’re unable to delete a virus or malware off our computers, and when this happens, we’ll need to remove some of our data. Occasionally, file corruption from harmful code may mean we have to reformat our hard drives. Without a backup, there’s no way to recover any lost data. This is even more critical since hard drives may accidentally corrupt themselves and cost us our files. However, a backup that contains the virus and malicious code will only repeat the issues we’ve experienced until we don’t back up the malware.
Use a strong password
A password is the first line of defence that protects our accounts from anyone trying to gain unauthorized access into them. Once someone’s into an account, they can steal data or place harmful content into cloud storage that may automatically update to the computer.
Watch the downloads
Websites can be sneaky when they’re loaded with malware and suspicious content. If a download starts that we didn’t authorize, we should immediately cancel it and exit the web page as it’s likely to be filled with more malicious code.
Install an Ad-block
Online pop-up advertisements can often lead to sketchy websites that steal our data and install viruses. It’s often easier said than done when trying to avoid these unless we download a reliable ad-blocker that stops us from seeing them all together.
Run a virus scan often
As great as all our ad-block and antivirus software is, there’s still potential to download a virus or install malware. As a result, we must run a virus scan at least on a weekly basis to prevent or minimize the damage done by malicious coding. This can be done moments before we backup to ensure we have no harmful files.
Avoid suspicious link
Links can be a dangerous thing, especially when they’re from an unknown source. A common trick that’s still used today is sending phishing emails that link to harmful websites that may install a virus or steal our data. Being careful about what we click on will save us from many potential threats.