A virus is a self-replicating program. This means that it can propagate, by itself, through different systems throughout a network. A virus requires some sort of user interaction to initiate its payload (program) and usually attaches itself to executable files or document files so as to trick a user into activating them.
A worm is also a self-replicating program. The difference between a worm and a virus is that a worm does not require any user interaction to initiate. For this reason, a worm may be considered a little more dangerous than a virus.
Malware is a term used for any software or program that is considered malicious. This is software that causes harm to systems, uses PC resources, or track user behaviors. This is a broad grouping of programs that include viruses, worms, Trojan horses, adware, and other related software.
Spyware is a malicious program that can ‘spy’ on user actions or track user movements through the Internet. These types of programs can report back to their creators and provide them with the keystrokes that were typed, the websites that were visited, or other sensitive information that the user may have on their computers.
A common result of an infected PC is that it may seem overworked or underpowered. In other words, your computer is no longer capable of executing the programs it always has with the same responsiveness. For example, if you attempt to access the Internet by double-clicking the icon and it takes the computer 2 minutes to open the program, this may be the result of other processes running in the background, such as a virus, worm, spyware, or other malware.
One of the easiest and probably one of the most effective security controls that can be implemented on systems is Anti-Virus, Anti-Spam, and Anti-Malware protection. It is just as important; however, to keep the virus signature files or DAT files, up to date. Since new malware programs or variants of existing malware programs are designed daily, it is important that the anti-virus solution that you implement is kept up to date to these threats. It is also recommended, especially when it comes to e-mail, that users not open any email messages that contain file attachments or have been delivered from an unknown source. Spyware or adware protection should also be used in conjunction with anti-virus on all systems and should be set up to actively scan and monitor these systems.
It is important to stay current on these threats. Here are some sources that can assist you on this: