While Windows were evolving as an application designed to facilitate the management of the DOS in a 32-bit operating system, the virus developers returned to using assembly as the main programming language to create viruses. Versions 5 and 6 of Visual Basic (VB) were, together with the Borland Delphi (Pascal language environments for Windows), the preferred development tool for creators of worms and Trojan horses. Then Visual C came into play, which offered a powerful application programming language for Windows. Quickly C was adopted by the creators of viruses, Trojan horses and worms. Viruses based on the Visual C language acquired unprecedented power, supplanting all other types of viruses. Although the characteristics of worms have changed with time, all have the same goal: to spread to as many computers in the shortest possible time.

Over time, Visual Basic became extremely popular and Microsoft implemented it as part of the functionality of a separate tool: an “interpreter” capable of executing script files that contained code with similar syntax.
Simultaneously, with the establishment of the 32-bit Windows platform, the first script file viruses were born: These were hostile software hidden inside a plain text file. Script file viruses showed that the executable files (files with extensions. EXE and. COM) were not the only ones that could carry viruses. As we have already seen with BAT files for viruses, there are other means of spreading a virus, fully justifying the assumption that everything that can be executed either directly or through an interpreter, may contain a hostile software. Specifically, the first viruses that could infect the macros contained in the applications of Microsoft Office came into the scene. As a result, Word, Excel, Access and PowerPoint have become vehicles for the spread of lethal weapons, which destroy data even when users simply open a document.

• Use a hardware or software firewall. A hardware firewall is usually embedded in the Internet gateway router, and provides pretty good protection from attacks originated from the Internet. A software firewall installed on your computer can be also a very good solution, because it can provide firewall access protection to both inbound and outbound traffic from your computer.
• Use a good antivirus security suit. I would recommend a complete security suit which protects for different kind of malware, such as viruses, trojans, adware, worms etc.
• Use strong passwords for all the user accounts configured on your personal computer.
• Keep your operating system and other applications up to date with the latest security patches.
• Use a network monitoring tool to observe what connections are running on your computer. An example of a free tool is TCPView for Windows which shows you detailed listings of all TCP and UDP connections on your computer. This program can be used to observe if any hidden code is sending data from your computer without you knowing about it.

Now, what can happen if your computer is directly connected to the Internet without the security protections described above?

• Information or data theft: Your Credit Card number, email passwords, computer login passwords, personal details etc can be easily stolen with a keylogger, trojan etc.
• Spam: Your computer can be compromised and become an email spam sender to other computers.
• BotNet: The BotNet is a remotely-controlled network of “zombie” computers that are fully controlled and managed by a central location. If your unprotected computer is compromised, it can be used as a member of the BotNet network, launching attacks to other computers. This can lead to legal actions against you. 

• Virus: A virus is a malware program that is loaded on your computer without your knowledge, with the intent of doing some damage to your system. It normally attaches itself to another program or data file in order to spread and reproduce itself in other areas of the computer without the knowledge of the user. Normally a virus enters your computer through a spam email which has attachments (pictures or files) or by downloading infected programs from malicious sites. A virus can damage files or cause your computer to behave strangely.
• Warm: Warms are memory-resident malware threats that can spread across networks by exploiting possible Vulnerabilities in the TCP/IP stack implementation of the OS and/or specific applications. They load themselves into the memory of a remote system and then execute themselves … all without ever being written to a disk. A warm therefore can live on its own and propagate by copying itself from one computer to another. Worms can harm a network, can consume tremendous bandwidth, and can shut a computer down.
• The difference between viruses and worms is that a virus cannot replicate itself like a worm, and it usually affects the computer it has invaded. A worm acts autonomously, and uses a computer network in order to multiply itself and to send copies of itself to other systems. A virus needs a user action (e.g download of infected file, run a program etc) in order to propagate and spread itself.
• Adware: An adware is certainly less threatening than a Warm or Virus. Typically, adware components install alongside a shareware or freeware application and bring targeted advertisements to your computer. These advertisements create revenue for the software developer. Adware displays web-based advertisements through pop-up windows or through annoying advertising banners. It can slow down your computer by consuming cpu, memory and bandwidth.
• Spyware: A spyware is closely related with adware, since it is usually transmitted also via freeware/shareware applications that we often download. As soon as it is downloaded it installs itself in your PC without your knowledge, and starts to monitor your internet activity. The monitored information is then transmitted to a third party, in most cases to companies which are interested in creating your personal profile. Later on, it will start sending you advertising or other data.
• Trojan: It is a program that appears to be working properly but actually causes damage in some form. It is called a Trojan because it can enter your computer through operations considered harmless, for example, through a game or even through a virus tracking program, and so it can trick the user by hiding the underlying activity. Like the ancient Trojan Horse, the Computer Trojan can secretly open ports on your Home Network. In general, Trojan horses cannot multiply themselves as warms do, but they rely on people to pass them around. The idea is to make the program look like it’s something harmless, like a screen saver or joke, so it gets sent around.

Bottom line is that you don’t want any of those little nasty codes on your computer. Fortunately there are several tools in the security “Arsenal” that can help you fight all these malware threats:

Antivirus Software

Antivirus software is the countermeasure program used to “inoculate” computer viruses. The software is installed on your PC and checks against viruses all files on your computer as well as files attached in incoming emails. If it finds viruses, it immediately informs you and, in most cases, it quarantines/cleans the infected files. The Antivirus can detect and clean both viruses and worms.

The Antivirus tool is a “must-have” software if you want to browse the Internet safely. The Three Best Antivirus Software available on the market today (which I am currently using on my personal computers) are the following:

1. Norton from Symantec
2. Kaspersky Anti-Virus Products
3. Trend Micro

Complete Security Suite

A complete security suite is a collection of tools for defending against malicious threats for your computer. The security suite usually includes antivirus, antispam, firewall, antispyware etc. An example of such a suite is The Norton 360 All-In-One Security

Although a security suite can help you prevent more types of malware compared with the standalone antivirus, the disadvantage of this software is that it takes more computer resources compared with a single antivirus solution.