Typically, adware components install alongside a shareware or freeware application. These advertisements create revenue for the software developer and are provided with initial consent from the user. Adware displays Web-based advertisements through pop-up windows or through an advertising banner that appears within a program's interface. Getting pop-up advertisements when youíre working on your computer is very annoying.
Often installing as a helpful browser toolbar, hijackers may alter browser settings or change the default home page to point to some other site.
Internet browsers write and read cookies, files with small amounts of data (such as site passwords and settings) based on instructions from Web sites. In many cases, cookies provide a benefit to users. However, in some instances cookies are used to consolidate and track user behavior across different sites, which provides marketers with private information about an individual.
Data theft can be as simple as mining your email address or as complex as complete identity theft. The results can vary from an increase in unwanted email spam from having your address published on hundreds of lists, to complete financial ruin from malicious credit card hijackers.
Most serious data theft is illegal and can be prosecuted.
Spyware often installs as a third-party component bundled with a freeware or shareware application, just like adware, making the distinction between the two somewhat vague. Spyware includes code used to gather and transmit information about the user or his or her behavior to a third party. This statistical data often is collected without the knowledge or consent of the user.
Trojan horses slip into an individualís system and run without the userís knowledge. They can have many functions. For example, some use a computer's modem to dial long-distance, generating huge phone bills for the computer owner. Unlike viruses and worms, Trojan horses do not make copies of themselves.
A computer virus is a program designed to spread itself by first infecting executable files or the system areas of hard and floppy disks and then making copies of itself. Viruses usually operate without the knowledge or desire of the computer user.
When you execute program code that's infected by a virus, the virus code will also run and try to infect other programs, either on the same computer or on other computers connected to it over a network. And the newly infected programs will try to infect yet more programs.
When you share a copy of an infected file with other computer users, running the file may also infect their computers; and files from those computers may spread the infection to yet more computers.
A Web Bug is a graphic image on a Web page or in an Email message that is designed to monitor who is reading the Web page or Email message. Web Bugs are often invisible because they are typically only 1-by-1 pixel in size. They are represented as HTML IMG tags.
A Web Bug on a webpage is generally used for counting and tracking and while their secret use may be offensive to some they are not a security threat.
Web bugs as graphic images in MIME email are generally used for the same counting and tracking reasons but may also include dangerous threats within their modified source code.
A computer worm is a self-replicating computer program, similar to a computer virus. A virus attaches itself to, and becomes part of, another executable program; a worm is self-contained and does not need to be part of another program to propagate itself.
In addition to replication, a worm may be designed to do any number of things, such as delete files on a host system or send documents via email. More recent worms may be multi-headed and carry other executables as a payload. However, even in the absence of such a payload, a worm can wreak havoc just with the network traffic generated by its reproduction.
A *personal firewall*, or software firewall solution isn't really a firewall. A firewall is a dedicated box with (usually) two or three ethernet ports running no services other than a firewall.
Please read the information provided in the link below before you choose a solution.
Email attachments with have been the most common method of sending viruses, worms and Trojan programs because their code will be executed by Windows and associated viewers or other MS programs when the attachment is opened. Windows uses the extension to determine what the default action on a file will be. For instance, a .txt file will open in Notepad and a .html file will open in Internet Explorer.
Common dangerous file extensions are:
Uncommon, but no less dangerous are file extensions
The information provided in the link below will help you avoid these email threats by setting your email client to plain text.
Links to some useful freeware installations.