robbiehay1
June 13th, 2008, 11:46 AM
What is a Computer Virus?
Computer viruses are everywhere. Their very names give computer users a scare — Klez, Melissa, W32, Michelangelo.
With the use of the Internet and endless communication between computers, viruses are spreading faster than ever. The only way to prevent their growth is through public awareness of safe computing.
It All Boils Down to the Code
A computer virus is simply a set of computer instructions or computer code that is written by some unscrupulous person. This code is attached to some part of the normal computer operating system or computer program. Instructions in this code tell the computer to perform some task. This task is often a destructive one, such as deleting important information or crashing the hard disk. However, there are other benign viruses that may be only a slight aggravation. Some viruses have been known to do nothing more than put a large happy face on your computer screen.
How Does a Computer Get a Virus?
Just as a human virus is passed from person to person, a computer virus is passed from computer to computer. A virus can be attached to any file that you copy to your computer. If you download files from the Internet or copy programs or files from friends on floppy disks, you are very susceptible to viruses. Actually, anytime that you download files or put a floppy disk into your computer, you are susceptible to viruses.
Many viruses are spread through e-mail. Generally, you cannot get a virus from simply reading e-mail. Certain types of today's viruses, like Klez, are different. They are very dangerous because you do not even have to open an e-mail attachment to release the virus. Just opening the e-mail itself can release the dangerous bug.
Under normal circumstances, a virus becomes active when you execute a program that contains the virus. For instance, if you download a program from the Internet and it is infected with a virus, the virus will attack your computer when you activate the program. Viruses are everywhere. Although it is rare, viruses have even been found in commercial shrink-wrapped software.
How Do I Know If My PC Has a Virus?
The trigger that activates the virus can be almost anything. For instance, the virus can be activated the minute it is installed. On the other hand, it may initiate its dirty work the next time you start your computer. In many cases, a virus resides inside your computer in an inactive state, waiting for a certain event to happen. Like having a physical virus in your body, you can have a virus in your computer system and not even know it. A virus can wait patiently in your system and attack only on a certain date. Of course, in the time between the moment you contracted the virus and the time it made itself known to you, you may have innocently spread the virus to others.
Stop Viruses Before They Attack
A computer virus can do extensive damage. It can crash your hard disk. It can destroy all or some of your data. Many viruses do weird little things that adversely affect your computer. The most usual symptom of a computer virus is erratic behavior. The destruction can happen at any rate of speed and can affect almost any part of the computer. Viruses can spread quickly through today's intricate cyber world. If your computer starts to act a little weird, the first thing to do is to check for a virus.
If you are smart, you will stop viruses before they enter your computer. You can do this by purchasing a good virus protection program. Such a program will check all files for viruses. Once installed, an antivirus program can be set to work in the background. It will check all files before they enter your computer and will alert you if a virus is detected before it contaminates your system. If a virus is detected, your antivirus program will quarantine or eliminate it so that it cannot harm your computer.
Be very careful to purchase a virus protection program that matches your operating system. If you use a Mac, buy a virus protection program made especially for Macintosh computers. If you use Windows 98 or Me or XP, select a program that was written specifically for your operating system. Don't try to use a virus protection program that was written for Windows 95 on a Windows XP machine; this will really mess up your computer.
(written by By Sandy Berger)
(source http://www.aarp.org (http://www.aarp.org/))
Types of viruses
These are properly the most commonly known ones out there
Virus
A virus is a man-made program or piece of code that causes an unexpected, usually negative, event. Viruses are often disguised games or images with clever marketing titles such as "Me, nude."
Worm
Computer Worms are viruses that reside in the active memory of a computer and duplicate themselves. They may send copies of themselves to other computers, such as through email or Internet Relay Chat (IRC).
Trojan Horse
A Trojan horse program is a malicious program that pretends to be a benign application; a Trojan horse program purposefully does something the user does not expect. Trojans are not viruses since they do not replicate, but Trojan horse programs can be just as destructive.
Many people use the term to refer only to non-replicating malicious programs, thus making a distinction between Trojans and viruses.
Some threats and terms you may not have heard of
Adware
While not necessarily malware, adware is considered to go beyond the reasonable advertising that one might expect from freeware or shareware. Typically a separate program that is installed at the same time as a shareware or similar program, adware will usually continue to generate advertising even when the user is not running the origianlly desired program. See also cookies, spyware, and web bugs
Application Level Gateway
(Firewall) A firewall system in which service is provided by processes that maintain complete TCP connection state and sequencing. Application level firewalls often re-address traffic so that outgoing traffic appears to have originated from the firewall, rather than the internal host.
Back Door
A hole in the security of a computer system deliberately left in place by designers or maintainers. Synonymous with trap door; a hidden software or hardware mechanism used to circumvent security controls.
Crack
A popular hacking tool used to decode encrypted passwords. System administrators also use Crack to assess weak passwords by novice users in order to enhance the security of the AIS.
DMZ
Demilitarized Zone - A part of the network that is neither part of the internal network nor directly part of the Internet. Basically a network sitting between two networks.
Email Worm
A self-reproducing program which is distinguished from a virus by copying itself without being attached to a program file, or which spreads over computer networks, particularly via email.
Firewall
A system or combination of systems that enforces a boundary between two or more networks. Gateway that limits access between networks in accordance with local security policy. The typical firewall is an inexpensive micro-based Unix box kept clean of critical data, with many modems and public network ports on it, but just one carefully watched connection back to the rest of the cluster.
Fishbowl
To contain, isolate and monitor an unauthorized user within a system in order to gain information about the user.
Host
A single computer or workstation; it can be connected to a network.
Host Based
Information, such as audit data from a single host which may be used to detect intrusions.
IDEA
(International Data Encryption Algorithm) - A private key encryption-decryption algorithm that uses a key that is twice the length of a DES key.
IDIOT
Intrusion Detection In Our Time. A system that detects intrusions using pattern-matching.
IP Splicing / Hijacking
An action whereby an active, established, session is intercepted and co-opted by the unauthorized user. IP splicing attacks may occur after an authentication has been made, permitting the attacker to assume the role of an already authorized user. Primary protections against IP splicing rely on encryption at the session or network layer.
IP Spoofing
An attack whereby a system attempts to illicitly impersonate another system by using IP network address.
To be continued...
Computer viruses are everywhere. Their very names give computer users a scare — Klez, Melissa, W32, Michelangelo.
With the use of the Internet and endless communication between computers, viruses are spreading faster than ever. The only way to prevent their growth is through public awareness of safe computing.
It All Boils Down to the Code
A computer virus is simply a set of computer instructions or computer code that is written by some unscrupulous person. This code is attached to some part of the normal computer operating system or computer program. Instructions in this code tell the computer to perform some task. This task is often a destructive one, such as deleting important information or crashing the hard disk. However, there are other benign viruses that may be only a slight aggravation. Some viruses have been known to do nothing more than put a large happy face on your computer screen.
How Does a Computer Get a Virus?
Just as a human virus is passed from person to person, a computer virus is passed from computer to computer. A virus can be attached to any file that you copy to your computer. If you download files from the Internet or copy programs or files from friends on floppy disks, you are very susceptible to viruses. Actually, anytime that you download files or put a floppy disk into your computer, you are susceptible to viruses.
Many viruses are spread through e-mail. Generally, you cannot get a virus from simply reading e-mail. Certain types of today's viruses, like Klez, are different. They are very dangerous because you do not even have to open an e-mail attachment to release the virus. Just opening the e-mail itself can release the dangerous bug.
Under normal circumstances, a virus becomes active when you execute a program that contains the virus. For instance, if you download a program from the Internet and it is infected with a virus, the virus will attack your computer when you activate the program. Viruses are everywhere. Although it is rare, viruses have even been found in commercial shrink-wrapped software.
How Do I Know If My PC Has a Virus?
The trigger that activates the virus can be almost anything. For instance, the virus can be activated the minute it is installed. On the other hand, it may initiate its dirty work the next time you start your computer. In many cases, a virus resides inside your computer in an inactive state, waiting for a certain event to happen. Like having a physical virus in your body, you can have a virus in your computer system and not even know it. A virus can wait patiently in your system and attack only on a certain date. Of course, in the time between the moment you contracted the virus and the time it made itself known to you, you may have innocently spread the virus to others.
Stop Viruses Before They Attack
A computer virus can do extensive damage. It can crash your hard disk. It can destroy all or some of your data. Many viruses do weird little things that adversely affect your computer. The most usual symptom of a computer virus is erratic behavior. The destruction can happen at any rate of speed and can affect almost any part of the computer. Viruses can spread quickly through today's intricate cyber world. If your computer starts to act a little weird, the first thing to do is to check for a virus.
If you are smart, you will stop viruses before they enter your computer. You can do this by purchasing a good virus protection program. Such a program will check all files for viruses. Once installed, an antivirus program can be set to work in the background. It will check all files before they enter your computer and will alert you if a virus is detected before it contaminates your system. If a virus is detected, your antivirus program will quarantine or eliminate it so that it cannot harm your computer.
Be very careful to purchase a virus protection program that matches your operating system. If you use a Mac, buy a virus protection program made especially for Macintosh computers. If you use Windows 98 or Me or XP, select a program that was written specifically for your operating system. Don't try to use a virus protection program that was written for Windows 95 on a Windows XP machine; this will really mess up your computer.
(written by By Sandy Berger)
(source http://www.aarp.org (http://www.aarp.org/))
Types of viruses
These are properly the most commonly known ones out there
Virus
A virus is a man-made program or piece of code that causes an unexpected, usually negative, event. Viruses are often disguised games or images with clever marketing titles such as "Me, nude."
Worm
Computer Worms are viruses that reside in the active memory of a computer and duplicate themselves. They may send copies of themselves to other computers, such as through email or Internet Relay Chat (IRC).
Trojan Horse
A Trojan horse program is a malicious program that pretends to be a benign application; a Trojan horse program purposefully does something the user does not expect. Trojans are not viruses since they do not replicate, but Trojan horse programs can be just as destructive.
Many people use the term to refer only to non-replicating malicious programs, thus making a distinction between Trojans and viruses.
Some threats and terms you may not have heard of
Adware
While not necessarily malware, adware is considered to go beyond the reasonable advertising that one might expect from freeware or shareware. Typically a separate program that is installed at the same time as a shareware or similar program, adware will usually continue to generate advertising even when the user is not running the origianlly desired program. See also cookies, spyware, and web bugs
Application Level Gateway
(Firewall) A firewall system in which service is provided by processes that maintain complete TCP connection state and sequencing. Application level firewalls often re-address traffic so that outgoing traffic appears to have originated from the firewall, rather than the internal host.
Back Door
A hole in the security of a computer system deliberately left in place by designers or maintainers. Synonymous with trap door; a hidden software or hardware mechanism used to circumvent security controls.
Crack
A popular hacking tool used to decode encrypted passwords. System administrators also use Crack to assess weak passwords by novice users in order to enhance the security of the AIS.
DMZ
Demilitarized Zone - A part of the network that is neither part of the internal network nor directly part of the Internet. Basically a network sitting between two networks.
Email Worm
A self-reproducing program which is distinguished from a virus by copying itself without being attached to a program file, or which spreads over computer networks, particularly via email.
Firewall
A system or combination of systems that enforces a boundary between two or more networks. Gateway that limits access between networks in accordance with local security policy. The typical firewall is an inexpensive micro-based Unix box kept clean of critical data, with many modems and public network ports on it, but just one carefully watched connection back to the rest of the cluster.
Fishbowl
To contain, isolate and monitor an unauthorized user within a system in order to gain information about the user.
Host
A single computer or workstation; it can be connected to a network.
Host Based
Information, such as audit data from a single host which may be used to detect intrusions.
IDEA
(International Data Encryption Algorithm) - A private key encryption-decryption algorithm that uses a key that is twice the length of a DES key.
IDIOT
Intrusion Detection In Our Time. A system that detects intrusions using pattern-matching.
IP Splicing / Hijacking
An action whereby an active, established, session is intercepted and co-opted by the unauthorized user. IP splicing attacks may occur after an authentication has been made, permitting the attacker to assume the role of an already authorized user. Primary protections against IP splicing rely on encryption at the session or network layer.
IP Spoofing
An attack whereby a system attempts to illicitly impersonate another system by using IP network address.
To be continued...