Other Malicious Softwares

In the olden days of computing the only thing the viruses spread through is the infected floppies. The booting from infected floppies causes the viruses to spread in to the host machine. With the advancement of the technology the medium of spreading also widened. The medium of spreading became internet, pen drives etc. The internet service has resulted in the formation of several malicious softwares. There are several such softwares available in the internet.

• Trojans

The most important difference between the Trojans and viruses is that Trojans cannot spread themselves whereas the viruses spread themselves. The Trojans disguise themselves as useful softwares and the user will download and install it thinking that it is a useful software. He only recognizes the harmful effect of Trojans only after it has started its job.

The Trojan has two parts: a server and a client. The server is the part that is installed in the attacker's system. It is the client that disguised themselves as a useful software and get installed in the victims machine. The client is present in the peer to peer networks and unofficial download sites. Once the Trojans enter in to the victims site, it has vast capability of destruction. The Trojans are highly sophisticated that they can be used according to the wish of the attacker. The attacker can decide the degree of harmness that can be caused by the Trojans. There are different types of Trojans. Some of them are listed below. A Trojan could have any or one of the combination of the below mentioned functionalities.

• Remote Access Trojans

These Trojans give full control of the victim's machine to the attacker. The attacker can gather several information from the victim's machine including confidential thins like passwords, credit card number etc stored in the victim's machine.

• Password Sending Trojans

These type of Trojans possesses great threats even today. The purpose of these Trojans is to send the password stored in the cached memory. They can also steal the passwords as you enter the passwords. They then send it to the specified e-mail without the users knowledge. Passwords of the restricted sites, e-mail, messaging services and FTP services come under the threat of these Trojans.

• Keyloggers

These Trojans log victim's keystroke end send the log files to the attacker. They can be active in two modes: one in online mode and the other in the offline mode. The attacker can get several information including the passwords. The logs are send in the daily basis.

• Destructive

The only function of these Trojans is to destroy all files in the core system. They performs the destructive work according to the will of the programmer or can be programmed to work as a logic bomb which can be activated in a special date or time.

• Denial of Service (DoS) Attack Trojans

The main aim of this kind of Trojans is to reduce the bandwidth of the victims machine by increasing the net traffic. This makes the internet connection too overloaded to let the user to visit a website or download anything. One of the variation of this type of Trojans is the mail-bomb Trojan, whose main aim aim is to infect maximum systems as possible and simultaneously attack a specific e-mail address with random subjects and content that cannot be filtered. However today the e-mail service providers use advanced filters to filter out these malicious softwares upto an extend.

• Proxy/Wingate Trojans

These Trojans turn the victim's system into a Proxy/Wingate server. Thus the victim's machine will be opened to many other systems connected to the network. The attacker can easily use this victim's system to anonymously browse in to the restricted sites and access various risky internet services. The attacker can register domains or access pornographic sites with stolen credit card number or can perform several similar illegal activities.

• FTP Trojans

These Trojans are commonly very simple. But most of them does not exist today. It does nothing but opens the port for the FTP transfer that is port 21. So everyone connected to the network can access files from the victim's machine. Today the systems are password protected so that only attacker can connect to the computer.

• Software Detection Killers

The main aim of these Trojans is to kill the softwares or firewalls that protect your computer from malicious softwares. This will reduces your computer's defense to the malicious softwares and becomes easily vulnerable to attacks. These Trojans exists even today. Some anti-virus asks the displays a confirmation message when they are to be uninstalled.

• Worms

Computer worms are programs that reproduce themselves and run independently. They can travel across the network connections They are platform independent, so they can attack system running on any operating system. The difference between a worm and a virus is the method in which they reproduce and spread. A virus is dependent on a host file or a boot sector, and transfer of files between the machines to spread, while a worm can run completely independent and spread of its own through the network connections.

The security threat of worm is same as that of the viruses. Worms are capable of doing wide range of damages such as destroying essential files in the victim's computer, slowing it down to the maximum extend and even causes some of the essential programs to crash. Two famous worms are MS-Blaster and Sasser worms.

• Spyware

Spyware is also an Adware (advertising-supported software). Advertising in shareware products is a way for shareware authors to make money, other than by selling it to the user. There are several large companies that offer to place banner ads in their products in exchange for a portion of the revenue from banner sales. If the user finds the banner annoying, there is usually an opinion to get rid of it by paying the license fee.

Unfortunately, the advertising companies often also install additional tracking software in your system that is continuously using your internet connection to send the statistical data back to the advertisers. Although the companies claims that they did not collect any personal information from the user so that he will be anonymous, the fact is that there is a server running in your computer that will send the information about you and your surfing habits to a remote location using the bandwidth of your internet connection.

Spyware slows down the speed of your internet connection. They also reduces the processing power of your computer. Sometimes unwanted pop ups will irritate the user. It also changes the settings of your browser like changing the home page or default search engines. Many people does not consider it as illegal. But unfortunately there is no way to get rid of such nuisance.