A computer virus is a type of malware or malware that spreads between computers and damages data and software. Good cyber hygiene and anti-malware tools can protect you from all of these attack vectors. Therefore, it is important to keep your software up to date, use strong passwords, and protect your device with strong cybersecurity software. Multi-part viruses can be prevented by not opening attachments from untrusted sources and installing reliable antivirus software. This can also be avoided by cleaning the boot sector and the entire hard drive of the computer. Rootkit virus. A rootkit virus is a type of malware that installs an unauthorized rootkit on an infected system and gives attackers full control over the system with the ability to fundamentally modify or disable features and programs. Rootkit viruses are designed to bypass antivirus software that normally scans only applications and files. Newer versions of major antivirus and antimalware programs include rootkit scans to identify and mitigate these types of viruses. System crashes and unexpected shutdown of the computer itself are common indicators of a virus. Computer viruses cause computers to act in various strange ways, such as opening files, displaying unusual error messages, or randomly clicking buttons. A computer virus typically consists of three parts: the infection mechanism, which finds and infects new files, the trigger, which determines when the payload is activated, and the payload, which is the malicious code to execute.
[33] Prior to the spread of computer networks, most viruses spread on removable media, especially floppy disks. In the early days of the personal computer, many users regularly exchanged information and programs on floppy disks. Some viruses spread by infecting programs stored on these hard drives, while others install themselves in the boot sector of the hard drive and ensure that they run when the user boots the computer from the hard drive, usually accidentally. Personal computers of that time first tried to boot from a floppy disk if there was one left in the drive. Until floppy disks were no longer used, this was the most effective infection strategy and boot sector viruses were the most common in the « wild » for many years. Traditional computer viruses emerged in the 1980s, driven by the proliferation of PCs and the consequent increase in bulletin board systems (BBS), the use of modems and software sharing. Bulletin Board`s sharing of software has directly contributed to the spread of Trojans, and viruses have been written to infect commonly marketed software. Shareware and contraband software were also common vectors of viruses on BBSs. [81] [82] Viruses can increase their chances of spreading to other computers by infecting files in a network file system or a file system accessible by other computers. [83] The damage is due to system failure, data corruption, waste of IT resources, increased maintenance costs or theft of personal data. [9] While no amount of antivirus software can detect all computer viruses (especially new ones), computer security researchers are actively looking for new ways to enable antivirus solutions to more effectively detect emerging viruses before they become widespread.
[67] A power virus is a computer program that executes specific machine code to achieve maximum dissipation of CPU power (thermal power output for central processing units). Computer cooling units are designed to dissipate power to thermal design performance rather than maximum power, and a power virus could cause the system to overheat if it has no logic to shut down the processor. This can lead to permanent physical damage. Power-powered viruses can be malicious, but are often suites of test software used for integration testing and thermal testing of computer components during the design phase of a product or for product benchmarking. [68] The following measures may help prevent virus infection: To avoid detection by users, some viruses use different types of deception. Some older viruses, especially on the DOS platform, ensure that the last modified date of a host file remains the same if the file is infected with the virus. However, this approach does not fool antivirus software, especially those that maintain and date cyclic redundancy checks for file changes. [51] Some viruses can infect files without increasing their size or damaging the files. They accomplish this by overwriting unused areas of executable files. These are called cavity viruses. For example, the CIH virus or the Chernobyl virus infects portable executable files. Because these files have many empty spaces, the virus, which was 1 KB long, did not increase the file size.
[52] Some viruses attempt to evade detection by terminating anti-virus software tasks before they can be detected (e.g., Conficker). A virus can also use a rootkit to hide its presence by not appearing in the list of system processes or by disguising itself as an approved process. [53] In the 2010s, as computers and operating systems become larger and more complex, old concealment techniques must be updated or replaced. Defending a computer from viruses may require migrating a file system to granular and explicit permissions for each type of file access. [ref. needed] Network viruses are extremely dangerous because they can completely cripple entire computer networks. They are often difficult to detect because the virus could be hidden in any computer on an infected network. These viruses can easily replicate and spread by spreading over the Internet to devices connected to the network. Reliable and robust antivirus solutions and advanced firewalls are essential to protect against network viruses. Memory corruption can be described as the vulnerability that can occur in a computer system when its memory is changed without explicit allocation.
The contents of disk space are modified due to programming errors that allow attackers to execute arbitrary code. Description: Memory errors occur primarily in low-level programming languages such as C or C++. This is one of the unwanted pop-up ads most likely to be associated with computer viruses and malware. Never click on pop-up ads, as this may result in the accidental downloading of viruses to a computer. Virus damage can be reduced by creating regular backups of data (and operating systems) on various media that remain unconnected to the system (most often, such as on a hard drive), are read-only, or are inaccessible for other reasons, such as using different file systems. This way, if data is lost due to a virus, you can reuse the backup (which hopefully will be new). [106] If a backup session is closed on optical media such as a CD and DVD, it becomes read-only and cannot be affected by a virus (until an infected virus or file has been copied to the CD/DVD). Similarly, an operating system on a bootable CD can be used to boot the computer if the installed operating systems become unusable. Removable media backups should be carefully checked before restoration. For instance, the Gamima virus is spread via removable flash drives. [107] [108] Execution phase: The virus program is now running and releasing its payload, the malicious code that damages your device.
A multipart virus uses several methods to infect and spread computers. It usually stays in the computer`s memory to infect the hard drive, and then spreads and infects more drives by modifying the contents of applications. This results in performance delays and application memory exhaustion. Here are some types of computer viruses that spread over the Internet: Downloads: Hackers can hide viruses in applications, documents sent through file-sharing services, plug-ins, and most other places where files can be downloaded. Trojan horse or Trojan horse is the name given to a computer virus. It is a type of computer software disguised as ordinary software such as utilities, games, and sometimes even antivirus programs. Once it runs on the computer, it causes problems like shutting down background system processes, deleting data from the hard drive, and corrupting file association systems. Description: Most of the time, Trojans are Some viruses use polymorphic code in a way that significantly limits the mutation rate of the virus. For example, a virus can be programmed to mutate only slightly over time, or it can be programmed not to mutate if it infects a file on a computer that already contains copies of the virus. The advantage of using such slow polymorphic code is that it becomes more difficult for antivirus experts and investigators to obtain representative samples of the virus, as infected « bait files » in a single pass usually contain identical or similar examples of the virus. This makes it more likely that the virus scanner`s detection is unreliable and that some instances of the virus can be prevented from being detected.
Virus writers use social engineering deception and use detailed knowledge of vulnerabilities to infect systems and spread the virus first. Viruses use complex anti-detection/stealth strategies to bypass antivirus software. [7] The motives for creating viruses can be the pursuit of profit (e.g., with ransomware), the desire to send a political message, personal amusement, proving that a vulnerability exists in software, sabotage and denial of service, or simply because they want to investigate cybersecurity issues, artificial life, and evolving algorithms. [8] Most modern antivirus programs try to find virus patterns in regular programs by scanning them for virus signatures. [58] Different antivirus programs use different scanning methods to identify viruses.