A computer virus is a specially written, small-sized program attached to other applications. When launched, a malicious utility can clog up RAM, load unwanted modules, block access to sites and perform a number of other undesirable actions on a PC. Users often do not even think about the fact that a computer virus infection can occur during normal work with files.
Operating principle
The application inside which the malicious code is located is infected. When such a utility starts, the virus takes control of the program. In order to prevent the user from detecting malicious code, actions to infect other applications can be performed only if certain conditions exist.
The virus has the ability to reproduce itself. This feature is inherent in all types of malware. The virus uses codes of other applications, data on the file structure, and even the names of programs. In this way, control is transferred to a malicious utility.
Ways of penetration of viruses into the PC
How do such programs get to the PC? Computer virus infection can occur during the process of downloading an application from a disk containing malicious code. Running the utility is optional. It is enough to restart the PC, forgetting to remove the removable media. At this point, the virus enters the system.
To infect a disk is very simple. One has only to insert it into the optical drive of the infected PC and read the table of contents as the virus immediately gets onto removable media. Malicious programs can infect PCs not only when using a removable drive, but also when downloading and processing files, installing an infected operating system.
How does the mail virus infection happen?
It happens that a user views emails in a browser and suddenly discovers the results of a malicious program on a PC. In this case, the drive is empty, and other applications are closed. How does malicious code get into the PC? Computer virus infection can occur while using the Internet.
Attachment files are often sent along with emails. Through them, the virus enters the PC. Messages sent in HTML format often contain links to malicious programs on the Web. In some cases, a computer virus infection may occur while reading the letter itself. When viewing a message, malicious code is activated.
Once on the PC, the virus extracts the contact addresses from the mail program. He then sends his code to other users. Using this method, the virus spreads rapidly over the Internet.