Good evening people. How are you all today? I would like to share information about Malicious Software: Viruses, Worms, Trojan Horses and Spyware.

Malicious software programs refered to as malware include a variety of threats such as computer viruses, worms and trojan horses. A computer virus is a rogue software program that attaches itself to other software programs or data files in order to be executed, usually without the user knowledge or permission. Most computer viruses deliver a "payload". The payload may be relatively benign, such as the instructions to display a message or image, it may be highly destructive - destroying programs or data, clogging computer memory, reformatting a computer's hard drive or causing programs to run improperly. Viruses typically spread from computer to computer when humans take an action as sending e-mail attachments or coping an infected file.

Many recent attacks have come from worms, which are independent computer-programs to copy themselves from one computer to others over a network. Unlike viruses, they can operate on their own without attaching to other computer program files and rely less on human behaviour in order to spread from computer to computer. Worms can destroy data and programs well as disrupt or even halt the operation of computer networks.

Worms and viruses are often spread over the Internet from files or downloaded software, from files attached to e-mail transmissions, or from compromised e-mail messages. Viruses have also invaded computerized information systems from "infected" disks or infected machines. Today e-mail attachments are the most frequent source of infection, followed by Internet downloads and Web browsing.

A Trojan horse is a software program that appears to be benign, but then does something other than expected. The Trojan horse is not itself a virus because it does not replicate, but is often a way for viruses or other malicious code to be introduced into a computer system. An example of a modern-day Trojan horse is Trojan.Xombe, which was detected on the Internet in early 2004. It masqueraded as an e-mail message from Microsoft, directing recipients to open an attached file that purportedly carried an update to the Windows XP operating system. When the attached files opened, it downloaded and installed malicious code on the compromised computer. Once this Trojan horse was installed, hackers could access the computer undetected, steal passwords and take over the machine to launch denial of service attacks on other computers.

Some types of spyware can also act as malicious software. These small programs install themselves on computers to monitor user Web surfing activity and serve up advertising. Some Web advitisers use spyware to obtain information about users' buying habits and to serve tailored advertisments. Many users find such spyware annoying and some critics worry about its infrigement on computer users' privacy.

Thats all for today. Have a nice day.