Different Types of Computer Viruses Computer virus is a software program written with malicious intentions. There are number of computer viruses that can impede the functioning of your computer system. Let us find out the different types of computer viruses. Did You Know? In 2010, Stuxnet virus targeted Siemens Industrial Software and Equipment. There are allegations that this virus is a part of a U. S. and Israeli intelligence operation named “Operation Olympic Games” and it hit Iran’s nuclear plant Natanz. Computer virus is a harmful software program written intentionally to enter a computer without the user’s permission or knowledge.
It possesses the capability to reproduce itself, thereby persistently spreading. While some viruses merely duplicate, others have the potential to cause significant damage or negatively impact the program and functioning of the system. It is crucial never to assume a virus is harmless and allow it to remain on a system. Various types of viruses exist, which can be categorized based on their source, methods, target file types, hiding places, destructive effects, operating systems, or platforms they target. Let us examine a couple of these viruses. One such example is the Memory Resident Virus.
These viruses have the ability to embed themselves in the computer’s memory and become active whenever the operating system is running, thereby infecting any files that are subsequently opened. One type of virus, known as a hideout virus, hides within the computer’s RAM even after its malicious code has been executed. It takes control of the system memory and allocates memory blocks to run its own code, which is executed when any function is carried out. The targets of this virus include files and programs that are opened, closed, copied, renamed, and so on. Some examples of this kind of virus include Randex, CMJ, Meve, and MrKlunky. To protect against these viruses,
it is recommended that an antivirus program be installed.
Direct Action Viruses are designed to replicate and take action upon execution. Once a certain condition is met, these viruses infect files in specified directories or folders, as outlined in the AUTOEXEC.BAT file path. The AUTOEXEC.BAT file resides in the root directory of the hard disk and performs certain operations during computer startup. These viruses employ the FindFirst/FindNext technique to select specific files as targets. In addition to infecting local directories, Direct Action Viruses can also propagate to external devices such as pen drives or hard disks by copying themselves onto these devices.
The viruses spread to various files and are usually located in the root directory of the hard drive upon execution. Their primary goal is to harm files by functioning as file-infecting viruses, with the Vienna virus serving as an illustration of this category. To safeguard against this virus, it is advisable to install an antivirus scanner. Nevertheless, it should be emphasized that this virus has a minimal impact on the computer’s performance. In comparison, overwrite viruses are recognized for erasing data within infected files, making them partially or entirely unusable post-infection.
Hideout is a virus that replaces the content of a file without changing its size. Examples of such viruses are Way, Trj. Reboot, and Trivial. D Protection is important because the only way to clean an infected file is to delete it completely, which means losing the original content. However, it is easy to detect this type of virus because the original program becomes useless. Another type of virus is the Boot Sector Virus, which targets the boot sector of a hard disk. This sector contains important information about the disk and a program that allows the computer to start from the disk.
This type of virus is known as Master Boot Sector Virus or Master Boot Record Virus. It hides in the memory until DOS accesses the floppy disk, infecting whichever boot data is accessed. Examples of this virus include Polyboot. B. The best way to avoid boot sector viruses is to make sure that floppy disks are write-protected and to never start your computer with an unknown floppy disk in the drive. Macro viruses infect files created using certain applications or programs that have macros, such as .doc, .xls, .pps, .mdb, etc.
These mini-programs enable the automation of sequences of actions, eliminating the need for manual execution. These viruses infect files with macros, as well as the templates and documents within them. They are categorized as e-mail viruses and may hide in documents shared over e-mail or networks. Examples include Relax, Melissa, A, Bablas, and O97M/Y2K. The most effective protection method involves refraining from opening e-mails from unfamiliar sources and disabling macros to safeguard valuable data.
Directory viruses, also known as Cluster Virus/File System Virus, infect the directory of a computer by altering the file path that indicates the file’s location. When running a virus-infected program file with a .EXE or .COM extension, the user unknowingly executes the virus program while the original file and program are relocated by the virus. This infection makes it difficult to find the original files. The virus typically resides in a single location on the disk but infects all programs within the directory.
Dir-2 virus Protection: The only solution is to reinstall all infected files from the backup and format the disk. Polymorphic Virus: These viruses use various encryption algorithms and keys to encrypt or encode themselves differently with each infection, making it impossible for antivirus software to detect them through string or signature searches. Additionally, they generate numerous copies. Some examples of polymorphic viruses include Elkern, Marburg, Satan Bug, and Tuareg.
Protection: Install an advanced antivirus as regular ones cannot detect this particular virus type. Companion Viruses, such as resident or direct action types, are a form of file infector virus. They are called companion viruses because they “accompany” existing files once they enter the system. In other words, these viruses can either wait in memory until a program is executed (resident virus) or instantly create copies of themselves (direct action virus) in order to carry out their infectious activities.
Hideout: In general, hideout viruses use the same filename but have a different file extension. For instance, if there is a file called “Me.exe”, the virus will create another file named “Me.com” and hide within it. When the system calls for the filename “Me”, the “.com” file will be executed instead (since “.com” has higher priority than “.exe”), leading to system infection. Examples of these types of viruses include Stator, Asimov.1539, and Terrax.1069.
Protection: To protect against hideout viruses, it is recommended to install an antivirus scanner and download a firewall.
FAT Virus: The file allocation table (FAT) is a disk component that stores information about file locations, available space, unusable space, and more.
Hideout: The FAT virus targets and can potentially harm the FAT section of a disk, which contains crucial information. This virus is particularly dangerous because it can block access to specific areas where important files are stored. The damage caused can lead to the loss of individual file data or even entire directories. Examples of protection against this virus include using Link Virus Protection, which involves identifying necessary files on the hard drive and removing any unnecessary ones that may have been created by viruses. Additionally, multipartite viruses have the ability to spread through multiple methods.
The action of a virus can vary depending on the operating system and the presence of certain files. At first, these viruses hide in the memory like resident viruses, then they infect the hard disk. Examples of such viruses include Invader, Flip, and Tequila. To protect against them, you need to clean the boot sector and the disk, then reload all the data. Make sure the data is free of viruses.
There is also a type of virus called web scripting virus that takes advantage of complex codes used in web pages to create interesting and interactive content. These codes can be exploited to cause undesirable actions.
Hideout: The main sources of web scripting viruses are web browsers or infected web pages. Examples include JS. Fortnight, a virus that spreads through malicious emails. Protection: Install the Microsoft tool application, which is a default feature in Windows 2000, Windows 7, and Vista. Scan the computer with this application. Worms, similar to viruses, can self-replicate and potentially harm your system. However, they can be detected and eliminated by antivirus software. Hideout: These worms typically spread through emails and networks.
Viruses such as PSWBugbear. B, Lovgate. F, Trile. C, Sobig. D, and Mapson do not cause damage or infect files but they have the ability to quickly duplicate themselves and potentially crash the entire network. To safeguard against these viruses, it is crucial to install an updated version of antivirus software.
Trojans differ from viruses or worms in that they are a form of malicious code that does not spread independently. Instead, trojans masquerade as useful programs or applications and can both copy and delete files on your computer while also granting attackers access to your information.
Logic bombs are not considered viruses; rather, they are concealed segments within other programs that only activate under specific conditions with the aim of destroying computer data. Logic bombs may remain unnoticed until triggered, which can result in significant destruction and loss of all data.
Viruses that affect Palm OS were first observed in 1996 upon its initial launch, and became more significant with the stable release in 2007. These malicious codes include the “Liberty” Crack, a Trojan horse that erases all files and applications from your PDA, PEMagic, which allegedly deletes the ROM, Phage, for deleting files, and Vapor, also causing file deletion. However, there is currently no concrete evidence indicating the extent of damage these viruses can cause, thus suggesting that there is not a significant threat to PDAs in terms of virus attacks.
Viruses impacting Symbian OS have no known threats. The only known virus affecting smartphones is the Cabir virus, however, it only operates in the background and drains battery power. The belief that these viruses spread through Bluetooth has been debunked. In this year alone, there have been virus attacks that pose a threat to files and applications. Let’s take a look at the worst viruses of 2012:
- Flame: This was the first known virus to use Bluetooth as a means of spreading. It was initially discovered in a lab in Russia.
- Belgian Computer Crime Virus: This virus spread worldwide and requested users to provide important information and pay a processing fee, claiming it was for police records.
- Shamoon: This dangerous virus creates files of data on the hard disk and sends the compiled data to the attacker.
In addition, there are many other computer viruses with the potential to infect your digital data. It is crucial to protect your data by installing genuine antivirus software.
