The new-age computing has also brought about a new breed of malicious software. Today, the word ‘virus’ has developed into a common term, normally used for all the ways a computer can be attacked by malicious software. In addition to the regular type of computer viruses, here is a glance at some of the newer malicious software problems we face nowadays.

Trojan Horses

The principal variation between a Trojan Horse, or Trojan, and a virus is that Trojans don’t spread themselves. Trojan horses disguise themselves as valuable and useful software available for download on the internet. Many inexperienced clients download and execute/install them, simply to understand their fault later.

A Trojan Horse is typically separated into two parts – a server and a client. It’s the client that is cleverly disguised as significant software and positioned in peer-to-peer file sharing networks, or unauthorized download websites. Once the client Trojan executes on your computer, the attacker i.e. the person running the server, has a high level of control over your computer, which can lead to destructive effects depending on the attacker’s purpose. Trojan Horses have developed to a remarkable level of cleverness, which makes each one radically different from each other. For an inclusive understanding, we have classified them into the following:

  1. Remote Access Trojans
    Remote Access Trojans are the most frequently available Trojans. These give an attacker absolute control over the victim’s computers. The attacker can go through the files and access any personal information about the user that may be stored in the files, such as credit card numbers, passwords, and vital financial documents.
  2. Password Sending Trojans
    The intention of Password Sending Trojan is to copy all the cached passwords and look for other passwords as you key them into your computer, and send them to particular email addresses. These actions are performed without the awareness of the users. Passwords for restricted websites, messaging services, FTP services and email services come under direct threat with this kind of Trojan.
  3. Key Loggers
    Key Loggers type of Trojans logs victims’ keystrokes and then send the log files to the attacker. It then searches for passwords or other sensitive data in the log files. Most of the Key Loggers come with two functions, such as online and offline recording. Of course, they can be configured to send the log file to a specific email address on a daily basis.
  4. Destructive Trojans
    The only purpose of Destructive Trojans is to destroy and delete files from the victims’ computers. They can automatically delete all the core system files of the computer. Destructive Trojan could be controlled by the attacker or could be programmed to strike like a logic bomb, starting on a particular day or at specific time.
  5. Denial of Service (DoS) Attack Trojans
    The core design intention behind Denial of Service (DoS) Attack Trojan is to produce a lot of internet traffic on the victim’s computer or server, to the point that the Internet connection becomes too congested to let anyone visit a website or download something. An additional variation of DoS Trojan is the Mail-Bomb Trojan, whose key plan is to infect as many computers as possible, concurrently attacking numerous email addresses with haphazard subjects and contents that cannot be filtered.
  6. Proxy/Wingate Trojans
    Proxy/Wingate Trojans convert the victim’s computer into a Proxy/Wingate server. That way, the infected computer is accessible to the entire globe to be used for anonymous access to a variety of unsafe Internet services. The attacker can register domains or access pornographic websites with stolen credit cards or do related illegal activities without being traced.
  7. FTP Trojans
    FTP Trojans are possibly the most simple, and are outdated. The only action they perform is, open a port numbered 21 – the port for FTP transfers – and let anyone connect to your computer via FTP protocol. Advance versions are password-protected, so only the attacker can connect to your computer.
  8. Software Detection Killers
    Software Detection Killers kill popular antivirus/firewall programs that guard your computer to give the attacker access to the victim’s machine.

Note: A Trojan could have any one or a combination of the above mentioned functionalities.

Computer Worms

Computer worms are programs that reproduce, execute independently and travel across the network connections. The key difference between a virus and worm is the manner in which it reproduces and spreads. A virus is dependent upon the host file or boot sector, and the transfer of files between computers to spread, whereas a computer worm can execute completely independently and spread on its own accord through network connections.

The security threat from worms is equivalent to that of viruses. Computer worms are skilled of doing an entire series of damage such as destroying crucial files in your system, slowing it down to a large degree, or even causing some critical programs to stop working. Two very prominent examples of worms are the MS-Blaster and Sasser worms.

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Spyware is the modern term for advertising-supported software (known as Adware). Advertising in shareware products is a method for shareware authors to make money, other than by selling it to the user. There are numerous large media companies that offer to place banner ads in their products in exchange for a portion of the revenue from the banner sales. If the user finds the banners annoying, there is generally an option to get rid of them by paying the licensing fee.

Unfortunately, the advertising companies often also install additional tracking software on your computer, which is constantly using your internet connection to send statistical data back to the advertisers. While the privacy policies of the companies claim that there will be no sensitive or identifying data collected from your computer and that you shall remain anonymous, the fact remains that you have a server sitting on your computer that is sending information about you and your surfing habits to a remote location, using your bandwidth.

Spyware has been famous to slow down computers with their semi-intensive usage of processing power, bringing up annoying pop-up windows at the most inappropriate times and changing your internet browsing settings such as your homepage or default search engine to their own services.

Even if many do not consider this illegal, it remains a major security risk, and the fact that there is no way to get rid of Spywares makes them as nasty as viruses.

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