Trojans, viruses, worms and bots — what is the difference and what they do

By | 24.04.2016

Viruses, worms, trojans and bots are part of the class of software called malware ( of malware) . The code or software that is specifically designed to damage, destroy, steal, or cause other damage to data or computer network.

There are many different classes of malware, which have different ways of infection and dissemination systems themselves. Some malware can infect the system being integrated into other programs or macros attached as a file. Other infect a computer using known vulnerabilities in the operating system (OS), network devices or other software. For example, using the hole in the browser that allows you to just visiting a malicious Web site to infect your computer. The vast majority, however, for the infection require some actions from the user, for example, open an email attachment or download a file from the Internet.

The most widely known types of malware are viruses, worms, Trojans, bots, backdoors ( a backdoor) , spyware and adware. The damage from malicious software vary from mild irritation causes (for example, pop-up windows in the browser) to steal confidential information or money, destruction of data, or damage to, or complete destruction of the system and the network.

Malware can not physically damage computer hardware and network equipment, but may cause damage to data and software stored on it. Malicious software is also not to be confused with defective software, which is intended for legitimate purposes, but has bugs and does not work correctly.

The two most common classes of malware — viruses and worms it. They are able to self-replicate and spread themselves across computers. They can even mutate to hide from anti-virus. The difference worm virus that worms are more independent from the carrier file, and for the dissemination of the virus require the file in which it is embedded code. Let’s examine what makes a virus, trojan, worm, bot. The Trojans differ from viruses and worms? Botnet — what is it? About everything in detail …

Computer viruses

A computer virus is a type of malware that spreads through the introduction of its copies to other applications. Thus the virus becomes a part of this program. It spreads from one computer to another, infecting all the computers on your way. Viruses differ in the severity of the consequences of causing mild irritation to data corruption and software or operating system failure. Almost all viruses are introduced into an executable file. This means that the virus can exist in the system, but it is not active and will not be distributed until the user launch or open an infected program file. At that time, when a basic code of the infected program, the virus code also runs. Typically, the host program continue to function after exposure. However, some viruses rewrite completely the code of other programs your code that affects the main program. Viruses spread when the software or document with which they are associated is transmitted from one computer to another using a network drive, file sharing, or infected e-mail attachments.


Computer viruses, worms, like in that they copy function copies of themselves and can cause the same type of damage. Unlike viruses, which require dissemination of the infected host file, the worms are standalone software and does not require the program host or help a person to reproduce. To spread, worms either use the vulnerability on the target system, or the user to launch them cheating. The worm arrives to a computer through a vulnerability in the system and uses the function of moving files or information in the system, which allows him to move around and infect computers without assistance.

Worms are the most dangerous class of malware proliferation and infect computers, since they spread and infect new computers do not need to run user-media files. For example, when connecting the USB drive to the infected computer, the worm infects its own, or has the opportunity to distribute their copies via network or email.

Trojans ( Trojan)

Troyan ( t Rojan) — type of malware, named after the wooden horse that the Greeks used to infiltrate the city of Troy. This malware that looks legitimate. Members are usually tricked into downloading and running it on your computer. It may look like the launch of a utility or even video. Such a file may be provided with a known program icon and have a similar name. Be like a video or image file to help the Trojans settings uolchaniyu system the Windows , which hides the extension for known file types. Thus, the type of file video.avi.exe displayed in Windows Explorer as a video.avi , which corresponds to the expansion of video files. In addition the file icon media player often has the Windows , that is confusing inattentive user and he runs it hoping to see the film.

Once the Trojan is activated, it can be in varying degrees of impact on the computer of annoying pop-ups and change the desktop to data corruption and OS (delete files, steal data, or activation and spread other malware, such as viruses). Troyan often create backdoors (a backdoor) , giving attackers access to the system. Recently, a large widespread Trojan-vinlokery ( Trojan.Winlock ), blocking your desktop .

Unlike viruses and worms, Trojans do not reproduce by infecting other files and are not able to reproduce. Trojan spreads by interacting with the user, such as opening an email attachment or downloading and running a file from the Internet.


«Boat» — derived from the word «robot» and is an automated process that interacts with other network services. Bots often automate tasks and provide information and services that could be made by man. A typical use of bots is to collect information (such as search engine crawlers looking for new sites), as well as automated human interaction (for example, voice mail or ICQ bot to tell jokes).

Bots can be used in both good and bad purposes. An example of the illegal actions may bot be no (bot network). A malicious bot distributes malware that infects computers and connects them through a backdoor to the central management server that can manage the entire network of compromised devices. Using bot-net an attacker can perform DDOS -ataki to sites or competitors’ server or on request. DDOS -ataki are a huge number of simultaneous requests to a server meaningless, coming from a variety of devices (infected computers), which leads to overload and hang the server and the inability normal operation and transmission of information (eg, the site stops working).

In addition to the ability to self-propagating worm-like, bots can record keystrokes, steal passwords, collect financial information to make DDOS -ataki, send spam. Bots have all the benefits of worms, but more versatile and in addition, part of a network that allows you to control the infected computers and to perform certain actions on command from the control center. Creating backdoors bots can download to your computer other malicious programs such as viruses or worms.

Bots in most cases, try not manifest itself to the user, so recognize that the computer is infected with is not easy.

Thus, malicious bots are the most dangerous in terms of the protection of information, as they are not only the subject and spread other malware, but also are able to perform their actions on command from the outside.

Exploits (Exploit)

Exploit is a piece of software commands or the methodology, which is aimed at breaking the specific security vulnerabilities. Exploits do not always have malicious intentions. They are sometimes used only as a way to demonstrate that the vulnerability exists. Nevertheless, they are a common component of malware.


Backdoors ( Backdoor)

What is a backdoor? Backdoor (literally «back door» or «backdoor») — this is an undocumented way of access to the system, which allows an attacker to compromise a system of an infected computer and manage it. Trojan backdoor ( Trojan.Backdoor) startup just opens the same «back door.» Usually attackers use backdoors for easy and continuous access to the compromised system. Through this backdoor pumped new malware, viruses and worms.

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