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Viruses Explained

What is a virus, worm, trojan? What is a bot, a botnet, a zombie? All this and more explained by Mary Landesman, your About.com guide to Antivirus.
  1. Spyware / Adware (39)
  2. Spyware and Adware
  3. Spyware and Adware
  4. Types of Viruses (121)
  5. Types of viruses
  6. Types of viruses

Mevade and Sefnit: Click Fraud Botnet
Medave and Sefnit are malware that are grouped together in the same family of botnets that use Tor to anonymize and hide its network traffic.

Top 5 Malware Threats
Top 5 Malware Threats; computer virus; new computer viruses; malware; phishing; fbi virus; firefox redirect virus; suspicious.emit; sirefef; loyphish

A Brief History of Malware; The First 25 Years
In January 2011, Brain - the first PC-based malware - turned 25 years old. (It's worth noting that the first computer virus was actually a Mac virus, Elk Cloner, in 1982). Following is a brief history of the first 25 years of malware evolution.

A Brief History of Malware; The First 25 Years
In January 2011, Brain - the first PC-based malware - turned 25 years old. (It's worth noting that the first computer virus was actually a Mac virus, Elk Cloner, in 1982). Following is a brief history of the first 25 years of malware evolution.

What are Autorun Worms?
Autorun worms are a type of malware that spread by taking advantage of the Windows autorun feature. Autorun allows executable files on a drive to be run automatically when that drive is accessed. The feature works via a file named autorun.inf. When a drive is accessed, Windows checks for the presence of autorun.inf and, if found, follows the...

Man-in-the-Browser Attacks (MitB)
A man-in-the-browser attack is like having a hidden enemy inside your Web browser. This "middleman" malware injects itself into the browser process, intercepting and handling all the back and forth communication between you and the website(s) you try to visit.

Browser Hijacking
Often accused of being drive-by downloads, these pesky Internet parasites can quickly take advantage of an improperly secured system. Find out how to protect yourself and which tools remove the pests.

What is a Botnet?
A botnet is a collection of infected computers under the control of one or more attackers. These botnets are used for a variety of criminal purposes – all of which pose serious risk to the infected user as well as to the entire Internet community.

Antivirus Glossary
From your About.com Guide to Antivirus, a glossary of terms commonly used when discussing malicious code and the antivirus technology used to defend against it.

Introduction to malware
What is a computer virus and how can it impact my system? These are fair questions but unfortunately a great deal of misinformation exists. This multi-lesson tutorial is designed to give you an accurate, broad perspective of malicious code and how to most effectively protect against it.

What is a Downloader Trojan?
A downloader trojan is similar to a backdoor, but with slightly different purpose.

Six Most Memorable Antivirus Mistakes

We all make mistakes and software engineers are only human. In antivirus programs, those mistakes can sometimes result in the loss of email and/or the deletion of important system files. Following are the six most memorable antivirus mistakes (all of which have since been fixed).

Understanding virus names
Antivirus vendors generally assign virus names consisting of a When attempting to find information about a particular virus, it can be helpful to understand how the virus names are formed.

A virus infects other files, by injecting the malicious code into the code of the legitimate file.

EICAR Test File
EICAR is not a virus. EICAR is a special file used to test antivirus software. Here's how to make an EICAR file to test your virus protection.

Free online security courses
Whether you need help understanding Windows or want to know what the difference is between a virus and a Trojan - and why it matters - these free online courses can help.

Malware Detection Methods
Malicious software comes in many different forms: viruses, worms, trojans, and advertising-related spyware and adware are the most common categories. But each category is also composed of many different types of threats. For example, within worms there are autorun worms, network worms, Internet worms, email worms, etc. There are equally as many...

Is your PC a zombie?
In the computer world, a Trojan can be used to turn your PC into their own computing matter - effectively turning it into a zombie machine.

What is Whitelisting
Traditional antivirus works via a blacklist approach, identifying known bad files and responding accordingly. The reverse of that approach, whitelisting, identifies all known good items.

What's in a (Virus) Name?
What do the virus names Shockwave, Pro Linux, W32/Prolin@mm, Troj_Shockwave, and Creative have in common? Shockwave, Pro Linux, W32/Prolin@mm, Troj_Shockwave, and Creative are all names of the same virus.

What is a RAT?
RATs, or Remote Access Trojans, provide a "backdoor" into the system through which the unscrupulous hacker can snoop into your system - even running other malicious code if s/he chooses.

What is a Rootkit?
A rootkit gives attackers full access to the system (hence the term 'root') and typically hides the files, folders, registry edits, and other components it uses. In addition to hiding itself, a rootkit typically hides other malicious files that it may be bundled with.

What is Behavior Blocking?
In its simplest form, behavior blocking monitors file activities, preventing certain modifications to the operating system or related files.

What is Pump and Dump?
Ever received one of those emails that pretends to be TO someone else, passing on some hot stock tip they've learned? Referred to as 'pump and dump' scams, the intent of the email is to get lots of people to take advantage of this unexpected windfall of information and buy the stock. Here's how it works.

Man in the Middle and Redirection Attacks
Man-in-the-middle attacks intercept communications between two points. During the interception, the MITM may record or even modify the communications between the two points.

Debunking Antivirus Conspiracy Theories
It's almost as certain as death and taxes - the 'it' being the constant recycling of the age old conspiracy theory surrounding antivirus vendors.

What is a Boot Sector Virus?
To understand what a boot sector virus is, one must first understand what a boot sector does. This tutorial provides the details.

2006: Year of Targeted Attacks
A look back at the emerging malware threats of 2006

MMORPG Trojans Abound
Trojans used to create botnets have long been implicated in spam and credit card fraud rings. But online games, particulary MMORPGs (Massive Multi-player Online Role Playing Games), are also a frequent target.

What is a Trojan?
A Trojan is a program that appears to be legitimate, but in fact does something malicious.

False Negative
A false negative occurs when a virus scanner fails to detect a virus in an infected file.

What is a virus?
The term 'virus' and its definition may have outlived its prime. In today's hostile computing environment, one would do better to ask, "what is malware?"

False Positive
A false positive occurs when a virus scanner erroneously detects a 'virus' in a non-infected file.

What is a Keylogger Trojan?
In its simplest form, a keylogger trojan is malicious, surreptitious software that monitors your keystrokes, logging them to a file and sending them off to remote attackers. Some keyloggers are sold as commercial software - the type a parent might use to record their children's online activities or a suspicious spouse might install to keep tabs on their partner.

What is a Virus Signature?
In the antivirus world, a signature is an algorithm or hash (a number derived from a string of text) that uniquely identifies a specific virus.

What is a DDoS Attack?
Trojans are often used to launch Distributed Denial of Service (DDoS) attacks against targeted systems, but just what is a DDoS attack and how are they performed?

How SpyBot Got Its Name
Controversy - real or manufactured - surrounds the name 'spybot'. Here's the history of the term from 1990 to present day use.

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