Need Assistance? 01384 442752 (UK)

Computer Bugs and Viruses

What are Computer Bugs? What are Computer Viruses?


Most software that is designed for computers cannot be tested to 100% perfect working order due to the vast size and complexity of different programs. Therefore many of the software products that are available (including operating systems) for consumers will cause certain problems to occur.

If the software being used is of an older type, it is likely that the bug has been discovered and a solution of some sort is available. If the product is brand new then you may not have the answer to your problem available right away, but you will be generally be welcomed by the support staff of  the  product concerned for discovering the bug. These individuals will then set about fixing the bug and deciding whether the problem is big enough to warrant marketing the solution.  You can locate software support staff by reading through the documentation that was provided with the software. Such documentation will usually be bundled in with the set up programs.


Viruses can be a technician’s worst nightmare. They can cause all sorts of problems preventing applications from working correctly to complete system failures. The first thing you should do when diagnosing a computer problem is to scan the hard disk for a virus. There are many virus scanning software packages available; some of the most popular ones are McAfee, Norton, F-Secure, and Kapersky.

There are also many different virus scans available as free downloads off the internet. These may do the job alright, but they might have expiry dates of 1 month etc., and you might have to constantly download new copies. Because new viruses are constantly being released, it is important to make sure you have the latest version of virus updates before scanning so that the software can detect all the latest viruses. New virus definitions are released daily for all the major software packages.

What is a Virus?

A computer virus is a type of program that invades computers and can perform a lot of functions  on  the  target  computer  such  as  displaying  pop  up  messages,  tampering  with personal files and data, or even deleting files and destroying the computer’s hard disk. There are also other types of attacks known as Trojan horses and worms, and these can also carry out malicious activities on the target computers that they infect.

When a computer is infected, the virus is generally executing its lines of code on that computer; therefore, the virus behaves like a parasite so that the computer would think that this piece of software is carrying out legitimate actions. Another nasty feature for a computer’s virus is that it can replicate itself and copy malicious code to other files and disks accessible from the infected computer, and can spread pretty quickly.

Before a computer virus runs and spreads to other computers or resources, it needs to be triggered or executed. For example, an excel sheet containing macros can become the home of a “macro virus”, and this virus will execute as soon as the spreadsheet is opened. There are several ways for a virus to spread: over a computer network, via attachments in emails, exchange of infected files on the internet, via downloading files from untrusted websites on the internet.

Bots and Botnets

A bot is an automated application that is used to perform repetitive tasks at a far quicker pace than a human would be able to. Some bots, known as web crawlers, are used to collect information for legitimate purposes.

However, not all bots are good, and malware bots are used for malicious purposes, being installed by attackers on unsuspecting computers. A bot is generally installed onto a computer by the means of a virus, a computer worm, a Trojan horse or other backdoors. They are pretty difficult to detect because they use work on the IRC (Internet Relay Chat) industry standard, which is used by popular client applications such as mIRC, Trillian Messenger, and many others.

Bots have grown in complexity over the years, and they are becoming increasingly difficult to be diagnosed, because more sophisticated bots have the capacity to host other bots. A “botnet network” is a term used to refer to a network of many computers which share programs processing amongst them. But the term botnets generally refers to a group of infected computers that host some sort of a robot software (i.e. a bot), and present a security threat to the computer owner. Any bot-infected computer is considered to be a drone or a zombie and it would have to follow the commands of the bot commander.

A botnet can be either large or small, based on the complexity of the bots being used. This means that small botnets are generally composed of only a few thousand zombies whereas large botnets are composed of tens of thousands of zombies.

Types of bots and their malicious uses

Below is a list of some commonly used bots:

  •  XtremBot, Forbot, Agobot and Phatbot
  •  RBot, UrBot, UrXBot, and SDBot
  •  GT-Bots and mIRC based bots

Malicious uses of botnets

There are several malicious applications for botnets. The most common botnet uses are listed below:

  • Denial of Service (DOS) attacks and Distributed Denial of Service (DDOS) attacks: botnets can be used in distributed denial of service attacks by sending network traffic to computer systems (such as computers, servers or mainframes) and computer networks. A DDOS attack can overload the computer system’s resources and cause a disruption of the services and might even cause a loss of network connectivity. Botnet attacks have also been used to attack and bring down websites by flooding the website with recursive queries and HTTP requests.
  • Network spamming: Botnets are also used to flood a computer network with spam emails and phishing emails, because they have the capacity of harvesting email addresses on compromised computers.
  • Traffic monitoring: Botnets can also be used in network traffic monitoring, by sniffing and locating sensitive information circulating on a network or passing through an infected computer. Once the data is located, a botnet can intercept this data and retrieve any usernames and passwords and other sensitive information.
  • Key logging: key loggers are little software programs that can be installed on infected machines and used to capture the keystroke sequences that the user types when they are using their computers. An intelligent key logger program is used to gather only the key sequences typed before or after specific keywords are typed (such as popular mail clients or bank logins), in order to capture usernames and passwords for such applications or websites and allow the intruder to use those login details at a later stage.
  • Identity theft: Bots are also commonly used on the internet to perform identity theft. This is achieved when the bot pretends to be a legitimate company and attempts to convince users to submit passwords and personal information such as their first and last name, age, location, credit card numbers, bank account numbers, etc. A common example is when users receive fishing emails containing links to fake websites such as online shopping website or financial institutions websites, asking the user to sign in using their username and password. Once the user enters their username and password, the bot will store this information and will obtain unlawful access to the user’s account.

Learn more about Computers and IT

We use computers and rely on IT systems everyday. These are becoming more and more complex as technology develops, and demand for knowledgeable specialists has never been higher as businesses and lives become more and more dependant upon them.

We have a great range of IT courses that you can study -

  • Improve your own knowledge.
  • Support your business better
  • Enter into the industry in roles such as -
    • Computer Servicing Technicians
    • IT Help Desk Support Staff
    • Programming
    • eCommerce
    • Website design, and more.

Study for your future - enrol on an IT course today - or get in touch with our highly knowledgeable IT tutors. They will be happy to answer any of you questions, or explain different study options relevant to you.

Learn More - Enrol in our Information Security Course

[26/01/2021 00:59:02]