Virus Definition Files and Tools for Virus Removal
An executable file virus, usually EXE files, is by inserting special code into some part of the original file so that malicious data can be executed when accessing the file.
The reason why a virus infects executable files is that, by definition, an executable file is a type of file that is executed and not just read. For example, EXE and MSI files (both executable files) are the files that run the code when opened.
These are different from non-executables like JPG files or macro-free DOCX files that simply serve to show you an image or a story.
Note: File viruses are sometimes called file infectors or simply viruses, and are incorrectly identified as keyloggers, adware, spyware, ransomware, or other forms of malware.
Types of Virus Files
Viruses are set apart from other types of malware in that they repeat themselves. It infects other executable files against user permission, and may or may not affect the overall performance of the device.
One type of virus is the write file virus, which completely overwrites the original file, replacing it with malicious code. These types of viruses must be removed immediately as nothing affected by the writing virus can be disinfected.
Loveletter, which works as an email worm, file virus, and trojan downloader, is a notorious example of a file overwriting virus. Loveletter searches for certain file types and writes them with their own malicious code, permanently destroying the contents of those files.
Another type of virus is one that simply drops a small amount of malicious code into the file. The program or executable device may run perfectly fine, but the virus is hidden inside and will be launched at a specified time (sometimes called a ticking bomb), or it may always be running but does not affect the usability of the file that has been infected.
Therefore, virus files can be created to navigate at certain starting points, such as when the file is opened or even when an unrelated event occurs, such as when another program is running. A file virus might be present in the secret and never affect anything until that trigger occurs.
This second type of file virus can usually be disinfected with an anti-malware program or anti-virus tool.
Other file viruses may replicate on the device or network to infect other executable files. It can even infect the boot sector and affect how the computer runs, sometimes causing your computer or device to be completely disabled until the harmful data is removed.
How to Recognize a File Virus
It is extremely important to be fully aware of the common file types for virus targeting. See a list of executable file extensions for files that you should monitor because they may harbor file viruses.
Some file viruses are saved in a deceptive manner to make you think they are harmless. For example, you can download a file named video.mp4.exe that appears to be an MP4 video file. As you can see, the real suffix is ".EXE" because these are the characters that follow the last period in the file name.
File infection viruses have targeted a range of operating systems, including Mac, Unix, Windows, Linux, and DOS. It can spread via email file attachments, online downloads, invalid URL links, and more.
Tip: See How to Download and Install Software Safely to learn how to protect yourself from virus file downloads.
How to Delete or Prevent File Viruses
It is best to remove viruses immediately before they can do any real damage. Make sure that you are running the latest version of the antivirus program of viruses so that they can take care of any existing threats immediately.
If you cannot log into your computer to delete a file virus or to check what is happening, try booting into safe mode if you are using Windows, or use a bootable antivirus program to scan your computer for file viruses before the operating system attempts to load.
Some viruses might be loaded into memory and appear locked when trying to remove them. You might be able to stop the virus process using Task Manager or some other tool that can close pesky processes.
See How to properly scan your computer for malware to learn more about how to delete viruses and other malicious software.
In addition to using antivirus software, one of the best ways to stop file viruses is to keep your operating system and software up to date. Use a free software updater to keep third-party software up-to-date, and Windows update to make sure Windows itself is always designed with the latest security fixes. It is a good option to use advanced antivirus like total security software.
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