A macro virus is a virus that can be embedded in a program (such as word processor) exploiting the fact it allows macro programs. A well known one is the mellisa virus.
A macro virus can be spread through email attachments, discs, networks, modems, and the internet. Uninfected documents contain normal macros. Most macros start automatically when a document is opened or closed. A common way for a macro virus to infect a computer is by replacing normal macros with the virus. The macro virus replaces the regular commands with the same name and runs when the command is selected. In this case where the macro is run automatically, the macro is opened without the user knowing.
Once the application opens a file that contains a macro virus, the virus can infect the system. At the lease, it will begin to embed itself in other documents and templates, as well as future ones created. It may corrupt other parts of the system as well, depending on what resources a macro in this application can get access to. As the infected documents are shared with other users and systems, the virus will spread.
A mail bomb virus is a denial of service attack, whereby a large and excessive (often millions) amount of e-mails are sent to an account often preventing retrieval of legitimate mail.
The three best ways to avoid this virus is to – make sure to download and apply any security patches available to your e- mail. Check your virus scanner has built in e-mail scanning. Apply a setting to your e-mails which most providers offer so e-mail can only be read in plain text format.
A Firewall is software or hardware, designed to monitor network traffic passing through a computer and denies or grants access based on a set of pre-determined rules.
Without proper configuration, a firewall can often become worthless. Standard security practices dictate a “default-deny” firewall ruleset, in which the only network connections which are allowed are the ones that have been explicitly allowed. Unfortunately, such a configuration requires detailed understanding of the network applications and endpoints required for the organization’s day-to-day operation. Many businesses lack such understanding, and therefore implement a “default-allow” ruleset, in which all traffic is allowed unless it has been specifically blocked. This configuration makes inadvertent network connections and system compromise much more likely.
A logic bomb is a piece of code intentionally inserted into a software system that will set off a malicious function when specified conditions are met. For example, a programmer may hide a piece of code that starts deleting files (such as the salary database), should they ever leave the company.
A worm is a self-replicating program that uses a network to send copies to other computer terminals in that network (Nodes). Unlike a virus it doesnt need to attach to an existing program.
Many worms have been created which are only designed to spread, and don’t attempt to alter the systems they pass through. However, as the Morris worm and Mydoom showed, the network traffic and other unintended effects can often cause major disruption. A “payload” is code designed to do more than spread the worm – it might delete files on a host system (e.g., the ExploreZip worm), encrypt files in a cryptoviral extortion attack, or send documents via e-mail. A very common payload for worms is to install a backdoor in the infected computer to allow the creation of a “zombie” under control of the worm author – Sobig and Mydoom are examples which created zombies. Networks of such machines are often referred to as botnets and are very commonly used by spam senders for sending junk email or to cloak their website’s address. Spammers are therefore thought to be a source of funding for the creation of such worms, and worm writers have been caught selling lists of IP addresses of infected machines. Others try to blackmail companies with threatened DoS attacks.
Anti virus software is affective against worms
Trojans (derived from the classic story of the Trojan horse) is a piece of malicious software that seems to perfrom one action when infact it is doing another, much like a virus.
A simple example of a Trojan horse would be a program named “waterfalls.scr” where its author claims it is a free waterfall screensaver. When run, it instead unloads hidden programs, commands, scripts, or any number of commands with or without the user’s knowledge or consent. Malicious Trojan Horse programs are often used to circumvent protection systems in effect creating a vulnerable system to allow unauthorized access to the user’s computer. Non-malicious Trojan Horse programs are used for managing systems, deploying software, surveillance, and forensics.
Since Trojan horses have a variety of forms, there is no single method to delete them. The simplest responses involve clearing the temporary internet files on a computer, or finding the file and deleting it manually. Normally, anti-virus software is able to detect and remove the trojan automatically. If the antivirus cannot find it, Rebooting the computer in Safemode (with or without networking) may allow an antivirus program to find a trojan and delete it.
A virus is a computer program that can copy itself and has a specific effect on a computer such as damaging programs and deleting files. This can have a disasterous effect on large computer systems like businesses as well as home computers.
With many computers connected to the internet and LANs (local area networks), the problems posed by virus’s has increased as they can spread far and quickly.
To stop them affecting your computer use antivirus software such as BitDefender or Kaspersky , these can cost up to $40 although there is some free software that can be found via downloads online. Of course people can also be vigilant about opening/viewing suspicious software and e-mails.
Currently doing a course at forth valley college stirling , using this blog for my internet safety class.
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