Computer viruses are small programs that spread from one computer to another and interfere with operations. They can corrupt or delete data, use email to spread, or erase hard disks. Viruses often spread through email attachments from unknown senders that appear to be images, cards, or files. Keeping computers updated and using antivirus tools can help avoid viruses.

1. by Asadbek Abdumannopov
IT safety: viruses

2. IT safety:Viruses.
WHAT VIRUS?
Computer viruses are small software programs that are designed to spread from one
computer to another and to interfere with computer operation. A virus might corrupt
or delete data on your computer, use your e- mail program to spread itself to other
computers, or even erase everything on your hard disk. Viruses are most easily spread
by attachments in e-mail messages or instant messaging messages. That is why it is
essential that you never open e-mail attachments unless you know who it's from and
you are expecting it. Viruses can be disguised as attachments of funny images,
greeting cards, or audio and video files. Viruses also spread through downloads on the
Internet. They can be hidden in illicit software or other files or programs you might
download. To help avoid viruses, it's essential that you keep your computer current
with the latest updates and antivirus tools , stay informed about recent threats , and
that you follow a few basic rules when you surf the Internet, download files, and open
attachments. Once a virus is on your computer, its type or the method it used to get
there is not as important as removing it and preventing further infection.

4. Dialer&Hijacker.
A spyware dialer is a malicious program that is installed on a computer and tries to use the dialing features to call other
numbers, often running up expensive phone bills for the victim. A dialer is unlike other types of spyware, though it is
sometimes included with free software-type downloads.
They are difficult threats to detect however, and it is not easy to prove that the dialer has been responsible for running up
telephone bills. Similarly, it is difficult to distinguish between a legitimate dialer and a spyware one, something that makes
this type of infection hard to identify. Spyware dialers are however easy to eliminate once the file where it resides has been
identified.
Browser hijackers, or simply hijackers, are a type of malware created for the purpose of modifying Internet browser
settings without the user’s knowledge or consent. Typically, hijackers change the homepage and default search settings.
However, some are known to inject advertisements—thus, they are qualified to be called adware, automatically redirecting
users to potentially malicious destinations when they visit certain sites, and sometimes making drastic changes to the
affected system. Some hijackers also contain keyloggers, which are capable of recording user keystrokes to gather
potentially valuable information they enter into websites, such as account credentials.

5. Backdoor.
A backdoor virus is malware that allows an unauthorized user into devices, applications, and networks. Attackers can gain
backdoor access using a command-line interface or other text-based commands. Backdoor viruses can install a script to
facilitate admin access, even after removing the malware. Once a backdoor virus is installed, attackers can log the activity
on the computer, steal sensitive data, and delete files.
Browser Helper Object.
A Browser Helper Object (BHO) is a DLL module designed as a plugin for the Microsoft Internet Explorer web browser to
provide added functionality. BHOs were introduced in October 1997 with the release of version 4 of Internet Explorer. Most
BHOs are loaded once by each new instance of Internet Explorer. However, in the case of Windows Explorer, a new instance
is launched for each window.
BHOs are still supported as of Windows 10, through Internet Explorer 11, while BHOs are not supported in Microsoft Edge.

6. Virus&Worm.
A worm virus refers to a malicious program that replicates itself,
automatically spreading through a network. In this definition of computer
worms, the worm virus exploits vulnerabilities in your security software to
steal sensitive information, install backdoors that can be used to access the
system, corrupt files, and do other kinds of harm.
Worms consume large volumes of memory, as well as bandwidth. This
results in servers, individual systems, and networks getting overloaded
and malfunctioning. A worm is different from a virus, however, because
a worm can operate on its own while a virus needs a host computer.

7. Spyware.
Spyware (a portmanteau for spying software) is software with malicious
behaviour that aims to gather information about a person or organization and
send it to another entity in a way that harms the user—for example, by
violating their privacy or endangering their device's security. This behaviour
may be present in malware as well as in legitimate software. Websites may
engage in spyware behaviours like web tracking. Hardware devices may also
be affected.[1] Spyware is frequently associated with advertising and
involves many of the same issues. Because these behaviors are so common,
and can have non-harmful uses, providing a precise definition of spyware is
a difficult task.

8. Trojan&Keylogger.
A Trojan Horse Virus is a type of malware that downloads onto a computer disguised as a legitimate program. The delivery
method typically sees an attacker use social engineering to hide malicious code within legitimate software to try and gain
users' system access with their software.
A simple way to answer the question "what is Trojan" is it is a type of malware that typically gets hidden as an attachment in
an email or a free-to-download file, then transfers onto the user’s device. Once downloaded, the malicious code will execute
the task the attacker designed it for, such as gain backdoor access to corporate systems, spy on users’ online activity, or steal
sensitive data.
Indications of a Trojan being active on a device include unusual activity such as computer settings being changed
unexpectedly.
Keyloggers are a particularly insidious type of spyware that can record and steal consecutive keystrokes (and much more)
that the user enters on a device. The term keylogger, or "keystroke logger," is self-explanatory: Software that logs what you
type on your keyboard. However, keyloggers can also enable cybercriminals to eavesdrop on you, watch you on your system
camera, or listen over your smartphone's microphone.

9. Although for our purposes, keyloggers operate in the context of malware, they are not
always illegal to install and use. Keyloggers are a common tool for corporations, which IT
departments use to troubleshoot technical problems on their systems and networks—or to
keep an eye on employees surreptitiously. The same goes for, say, parents, who want to
monitor their children’s activities. Suspicious spouses are another market for keyloggers.
In all such cases, if the organization or person downloading and installing the keylogger
actually own s the device, then it’s perfectly legal. And there are thousands of commercially
available keyloggers on the Internet, which advertise themselves for just such a use.
However, the concern about keyloggers is when malicious actors are behind them. And they
definitely do not own the device they infect. You don’t know they’ve breached your
computer; and depending on what kind of keylogger it is, it can steal any passwords you’ve
entered, periodically take screen shots, record the web pages you view, grab on to your sent
emails and any instant messaging sessions, as well as sensitive financial information (such
as credit card numbers, PIN codes, and bank accounts), and then send all that data over the
network to a remote computer or web server. There, the person operating the logging
program can retrieve it all, potentially sending it to third parties for criminal purposes.

10. Adware&Malware.
Adware is unwanted software designed to throw advertisements up on your screen, most often within a web browser. Some
security professionals view it as the forerunner of the modern-day PUP(potentially unwanted program). Typically, it uses an
underhanded method to either disguise itself as legitimate, or piggyback on another program to trick you into installing it on
your PC, tablet, or mobile device.
Adware generates revenue for its developer by automatically displaying online advertisements in the user interface of the
software or on a screen that pops up in the user’s face during the installation process. And that’s when you start seeing
dubious miracle weight loss programs, offers for get-rich-quick secrets, and bogus virus warnings that invite your click.
Also, you might experience new tabs opening, a change in your home page, findings from a search engine you never heard
of, or even a redirect to a NSFW website.
Malware, short for malicious software, refers to any intrusive software developed by cybercriminals (often called hackers)
to steal data and damage or destroy computers and computer systems. Examples of common malware include viruses,
worms, Trojan viruses, spyware, adware, and ransomware. Recent malware attacks have exfiltrated data in mass
amounts.Malware is developed as harmful software that invades or corrupts your computer network. The goal of malware is
to cause havoc and steal information or resources for monetary gain or sheer sabotage intent.

11. Malicious Software.
Malicious software, commonly known as malware, is any software
that brings harm to a computer system. Malware can be in the form of
worms, viruses, trojans, spyware, adware and rootkits, etc., which steal
protected data, delete documents or add software not approved by a user.

12. Email-Worm&Virus.
An Email-Worm (also known as a mass-mailer or less commonly, an Internet worm) is a type of worm that distributes
copies of itself in an infectious executable files attached to fake email messages.
Email-Worm typically arrive as executable files attached to fake email messages.
Some mass mailers randomly compose the subjects and bodies of the messages from words and phrases carried in the
worm's own code; other worms use content found in randomly selected files in the infected computer to compose the
message. The name of the file attachment can be either random, or 'borrowed' from other files.
Many worms send themselves as attachments with double extension, for example .MPG.EXE or AVI.PIF. Often, a
recipient will only notice the first extension listed and will try to open such attachments thinking, that they are multimedia
files.

13. Exercises
Exercise 1: Read the descriptions 1-8. Match the words in the box to the descriptions.

14. Exercise 2:Matching.
Exercise 3:Glossary.
Adware
Hacker
Browser hijacker
malware attack
Spyware
Worm
Malicious
Unautorised
Infect
Attempt
Engine