Date First Published: 21st June 2022
Topic: Cybersecurity
Subtopic: Threats To Systems, Data & Information
Difficulty: EasyDifficulty Level: 2/10
Learn more about what a computer virus is in this article.
A computer virus is a type of malicious program, script, code, or macro that is designed to harm a computer and spread from one device to another, usually over a network. Similar to a biological virus, a computer virus is something that you definitely do not want a computer to catch. Once a computer is infected with a virus, it could do almost anything of the virus writer’s choice, which is explained below.
Since computer viruses are solely designed to harm a computer system, they have no advantages.
Computer viruses can be spread in all sorts of ways. The most common ways that they are spread are:
This is the most common way that computer viruses spread. Sometimes, when users download files from an untrustworthy source, especially executable files (EXE) that run code when opened, they may contain viruses that harm computer systems. Some users will maliciously share viruses over a network and use deception tactics to get users to open them or disguise them as legitimate programs. Viruses are commonly spread through P2P programs, such as BitTorrent, especially since its possible for any user to share files with no restrictions.
Virus writers can use misleading file extensions to trick users into running malicious programs. This is usually accomplished by a double file extension. For example, a virus writer could name an executable file as ‘setup.jpg.exe’ to make it look like a ‘jpg’ file when it is actually an EXE file. Setting the option to show file extensions will make double extension files more noticeable.
Computer viruses can easily spread through email attachments when they are opened, especially when they look off, when they are from an unknown sender, and when they were not expected. These types of viruses always require user action, such as opening or downloading the attachment in order for them to spread.
Viruses don’t just spread over a network. They can spread through removable media, such as USB drives, CDs, and SD cards. If a virus is stored on removable media and is copied to another computer, it could cause that computer to catch the virus.
A computer virus can perform all sorts of malicious actions once it has infected a computer. A computer virus could:
The signs of a computer being infected with a virus are:
A virus is simply a piece of malicious code designed to harm a computer system. In most cases, a computer virus will not physically damage parts of a computer. However, viruses could heavily consume computing resources, such as the CPU and cause them to overheat. This could destroy the CPU.
Viruses on mobile devices are quite rare due to the closed sandbox, preventing third-party apps from being installed. However, iPhones and Android devices are still vulnerable to viruses, especially if they are rooted or jailbroken as that will allow unmoderated apps to be installed. In iOS, jailbreaking refers to the process of bypassing the security restrictions imposed by Apple that put a limit on the operation of apps on the device. In Android, rooting allows users to gain root access to the Android operating system code, equivalent to iOS jailbreaking.
There have been malicious programs that have harmed jailbroken and rooted mobile devices. An example that harmed iOS devices is KeyRaider, a malware that stole Apple ID credentials and other data from iOS devices by intercepting iTunes traffic. It had an effect on iOS devices in August 2015 and was known to have stolen over 225,000 Apple account credentials. It spread through third-party Cydia repositories. In addition, it was a form of ransomware as it locked the mobile devices and asked users to pay to unlock them.
DroidKungFu was a malware that had an effect on Android devices, mostly in China. This malware was first found in alternative Chinese Android Markets in March 2011. It targeted the Android 2.2 platform and allowed hackers to access and control devices. It also captured data from mobile devices.
Whilst the App Store and Google Play Store are the most trustworthy source for downloading apps to mobile devices and they have security procedures and guidelines to monitor the security apps, in the past, there have been malicious apps on those stores that got removed.
Computer viruses are created by cybercriminals that are out there to do harm and cause havoc. Often, cybercriminals create viruses with the intention of:
Most viruses are solely designed for cybercriminals to make money. A good example of this is a ransomware virus that encrypts files and demands victims to pay money in order to recover them.
For example, in September 2013, when the Cryptolocker ransomware was released and spreading to computers all around the world running Windows through infected email attachments, over 27 million USD was made by victims paying ransoms and the money that cybercriminals make from spreading viruses encourages them to create even more viruses.
Some viruses may not be strictly malicious. Instead, they may just slow down the victim's computer. For example, adware, a type of unwanted software that displays unwanted ads on a computer to generate revenue for its developer. The more computers that the adware spreads to, the more money the developer makes.
There are some people that enjoy causing issues for other people and seeing them suffer. Some viruses can bring down networks for large organisations around the world and cause extended periods of downtime. When cybercriminals know that they are causing all of this trouble, it will encourage them to create even more viruses.
There are viruses designed to capture sensitive information about victims so that the virus writer can sell the victim’s data to third parties. Information can include browsing history, email addresses, real names, passwords, profiles, and other sensitive information.
The terms ‘computer virus’ and ‘malware’ are slightly different. Malware refers to any type of malicious software that harms a computer system and a virus refers to a type of malware that copies itself in order to infect other devices.
If a computer is seriously infected with a virus, it may be necessary to reinstall the operating system to remove all traces of the virus. A full operating system reinstall will remove all programs installed from the computer, including viruses.
These methods below should help your computing from catching a virus. Once a computer has caught a virus, it can cause all sorts of issues. Therefore, it is much better to prevent a virus attack than to try and remove it.
The timeline of computer viruses can be seen below.
| Year | Event |
|---|---|
| 1971 | In order to verify John von Neumann's idea, Bob Thomas at BBN Technologies created the Creeper system, an experimental self-replicating program. TENEX-powered DEC PDP-10 computers that were infected with the Creeper virus. I'm the creeper, catch me if you can! was shown on the remote system after Creeper used the ARPANET to obtain access and copy itself there. Later, the Reaper programme was developed to remove Creeper. |
| 1972 | When HARLIE Was One, a science fiction book by David Gerrold, has one of the earliest fictional representations of a computer virus as well as one of the earliest instances of the term "virus" being used to describe a software that harms computers systems. |
| 1973 | In fiction, the 1973 Michael Crichton film Westworld introduced the idea of a computer virus as the main plot device that leads to androids going crazy. "There's a strong pattern here which indicates an analogue to an infectious illness process, spreading from one...area to the next," Alan Oppenheimer's character says in reference to the issue. "Perhaps there are superficial similarities to disease," and "I must admit I find it difficult to believe in a disease of equipment," are the responses given. (Crichton's earlier works, The Andromeda Strain, a 1969 novel, and The Andromeda Strain, a 1971 film, both dealt with a biological virus-like disease from another planet that threatened humanity.) |
| 1974 | It is written the Rabbit (or Wabbit) virus, which is more of a fork bomb than a virus. The Rabbit virus multiplies its copies on a single computer (it was given the nickname "Rabbit" for how quickly it accomplished this) until it clogs the system and lowers system performance, at which point it reaches a critical point and crashes the computer. |
| 1975 | John Walker's ANIMAL was written in April for the UNIVAC 1108. Whilst approximately similar PERVADE would duplicate itself and ANIMAL in each directory where the current user had access, ANIMAL queried the user with a series of questions in an effort to determine the type of animal the user was imagining. It spread to other computers when tapes were shared and across the multi-user UNIVACs when users with overlapping permissions learnt about the game. The program was carefully written to prevent harm to already-existing file or directory structures and to stop itself from copying if the necessary permissions were not present or if harm would come from doing so. An OS upgrade that altered the file status tables that PERVADE used to function was able to prevent it from spreading. |
| 1977 | In the novel "The Adolescence of P-1," a worm program that spreads across modem-based networks eventually develops its own AI strategy and deals with cross-hardware and cross-OS difficulties, infecting hardware manufacturers and security companies. |
| 1982 | Richard Skrenta, a student in his second year of high school, wrote the Apple II application Elk Cloner originally as a joke. Because its operating system was stored on a floppy disk, the Apple II was especially vulnerable. Elk Cloner was the cause of the first significant computer virus outbreak in history due to its design and people's lack of knowledge about malware and how to defend against it. |
| 1983 | November: Frederick B. Cohen re-invents the word "virus" to describe self-replicating computer programs In 1984, Cohen refers to the behaviour of these programs as a "infection" by using the term "computer virus" (a name his tutor Leonard Adleman offered). "A program that can 'infect' other programmes by altering them to include a possibly developed duplicate of itself" is how he defines a "virus," according to him. On a VAX11/750 system at Lehigh University, Cohen shows off a program that resembles a virus. Other system objects could become infected or have the virus install itself there. |
| 1984 | August: Ken Thompson publishes his seminal paper, Reflections on Trusting Trust, which he explains how he modified a C compiler so that, when used to compile a particular version of the Unix operating system, it inserts a backdoor into the login command and, when used to compile a new copy of itself, it inserts the backdoor insertion code—even though neither the backdoor nor the backdoor insertion code is present in the source code of this new copy. |
| 1986 | The Brain boot sector virus is made public in January. Brain is regarded as the first IBM PC compatible virus and the malware that caused the first widespread outbreak of IBM PC compatible viruses. The virus was developed in Lahore, Pakistan, by Basit Farooq Alvi, a 19-year-old Pakistani programmer, and his brother Amjad Farooq Alvi. It is also known as the Lahore, Pakistani, Pakistani Brain, and Pakistani flu. At a meeting of the secret Chaos Computer Club in Germany in December, Ralf Burger introduced the Virdem model of software. By adding their code to executable DOS files in COM format, the Virdem model represented the first software applications that could copy themselves. |
| 1995 | The first Macro virus, called "Concept", is created. Microsoft Word documents were targeted by it. |
| 2000 | May 5: Within a few hours of its distribution, the VBScript-based ILOVEYOU worm, also known as the Love Letter, VBS, or Love Bug worm, infected over 10 million Windows computers all over the world. It spread through email as a chain letter using the Outlook email application. |
| 2003 | In just 15 minutes after infecting its first victim, the SQL Slammer worm—also known as the Sapphire worm, Helkern, and other names—which targets flaws in Microsoft SQL Server—becomes the fastest-spreading worm ever as measured by the time it takes for its growth to double. It caused severe disruption to Internet access across the world. |
| 2005 | August 2005: The plug-and-play vulnerability in Microsoft operating systems, such as Windows 2000 is one of the security flaws that the computer worm Zotob exploits. On Microsoft-ds or TCP port 445, this worm has been observed to spread. |
| 2008 | The Trojan horse Torpig, sometimes called Sinowal and Mebroot, infects Windows and disables antivirus software. It gives others access to the computer, alters files, steals sensitive data, such as passwords, and infects the victim's computer with other software. |
| 2012 | On August 16, a computer virus called Shamoon was created specifically to attack Microsoft Windows-powered devices in the energy industry. On 16th August 2012, Symantec, Kaspersky Lab, and Seculert announced their discovery. |
| 2013 | The CryptoLocker Trojan horse was found in September 2013. The files on a user's hard drive were encrypted by CryptoLocker, which then demanded money from them in exchange for the decryption key from the developer of the ransomware virus. A number of clone ransomware Trojans were also found in the next few months. |
| 2014 | The Regin Trojan horse is found in November. Regin is a dropper that is mostly spread through fake webpages. Once installed, it silently downloads more malware, making it difficult for antivirus programs that rely on signatures to detect it. It is believed that the United States and the United Kingdom developed it as a tool for mass surveillance and spying. |
| 2016 | January: The "MEMZ" trojan is released. The trojan was created as a joke, according to its developer Leurak. The malware informs the user that it is one and warns them that if they continue, the machine can become unusable. It has complex payloads that damage the system and cause anomalies to appear on the screen as it runs. Once opened, the program cannot be closed without further harm to the computer, which will thereafter fail to function as intended. When the computer restarts, an error message appears in place of the bootsplash "The MEMZ Trojan has corrupted your computer. Enjoy the Nyan cat now "which is followed by a Nyan Cat cartoon. |
| 2017 | May: A worldwide ransomware outbreak called WannaCry occurs. The malware was spread through exploits that were made public in the 2016 NSA hacking toolkit leak. A "death switch" concealed within the ransomware was discovered and activated by a UK cybersecurity researcher that was working with others shortly after the news of the infections went viral on the internet. This successfully stopped the malware's initial wave of global transmission. The next day, researchers said that they had discovered fresh malware variants that were missing the kill switch. |
| 2021 | July: Journalists and researchers report the discovery of spyware called Pegasus, developed and distributed by a private company. Based on zero-day exploits, Pegasus can and has been used to infect iOS and Android smartphones frequently without the need for any user-interaction or significant clues to the user. Once installed, Pegasus can then be used to delete data, track user locations, capture footage with the camera, and turn on the microphone at any time. According to the study, it was used on several targets around the world, including journalists, politicians from opposing parties, activists, businesspeople, and others. |
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