TROJAN AND VIRUS: CONCEPTS AND ITS PRECAUTION

With the spread of broadband connections, viruses and trojans are a lot of talk right now. Indeed, it has become increasingly easy to break into the machines of individuals, not familiar with security techniques and whose machines are sometimes connected to the Internet 24 hours a day.

We will see in this article how to better know these programs which can be devastating and especially to study some simple techniques to protect themselves from them. Without sinking into paranoia.

Definitions and concepts

What is a virus?

A virus is a computer program that can spread autonomously from machine to machine and from file to file.

What is a Trojan?

A trojan, or trojan horse or even trojan, is a computer program which is installed by masking itself in another healthy program. It does not generally reproduce and is used as a base (server) to allow intrusions on a machine. The number of Trojans is as impressive as the variety of actions they allow. Some simply open access to the infested machine's files, others allow full interaction with it in the same way as if the intruder were in front of it.

It is a particular virus that reproduces itself through the Internet. He usually uses e-mail to reproduce himself from machine to machine.

What is a Port?

A port is a "virtual door" on a machine connected to a network. It is through this "door" that the information exchanged by the network passes. Some ports are almost assigned to certain services (example: port 80 is used for surfing the Internet (http port), port 21 is used for downloading (FTP port)) and ports 110 and 25 are used respectively for receiving and sending email by a POP server).

What does the verb "Hacker" mean?

The term "Hacker" literally means "code chopper", it initially designates a programmer who tries to find hidden bugs in programs. This term has now been deviated from its initial meaning and we will always find behind it a person who, driven by passion, searches for the faults of a system (and who is therefore someone very respectable) but also the one who thereby attempts to break into a system (a computer) illicitly or without the owner having given access to it (this is what we could call the "dark side of force"). By extension, "hacking" refers to the discipline of looking for the flaws in a system.

Why do viruses and trojans exist?

The two main reasons for the existence of these computer programs are profit and fame. Indeed, some people appreciate that the main media of the planet relay the exploits of a virus of their creation (each his own). There have also been several rumors that some anti-virus creation companies have a relationship with the virus makers. Indeed, without virus, the usefulness of an anti-virus is very reduced, nothing like a devastating virus to "boost" the sales of anti-virus. Trojans, on the other hand, can allow companies to acquire confidential data on their competitors. Finally, many users of trojans only use them to "play a good joke on a mate".

The main principle: to spread

A virus or a trojan is of little interest if it stays on the machine of its creator. They have always looked for flaws in systems in order to allow their creation to be widely disseminated.

Each generation has its own viruses: A few years ago, when the main means of data exchange between computer users was the 3 "1/2 floppy disk, it was the" boot viruses "that were wreaking havoc. small programs get lodged in a ridiculous space that is executed each time the floppy boots (boot), thus spreading from floppy disks to hard disks and from hard disks to floppy disks. With floppy disks having become almost obsolete, we now do not talk much about “boot virus.” Rather, it is the Internet that has become the most effective means for a virus to spread: document exchanges, file downloads, e-mails are now the main vectors of distribution.

Since software and operating system developers do their jobs (normally) well, when you have just installed a machine, it is supposed to be impossible for anyone to get into it. The work of virus or trojan creators is therefore to look for the loopholes that will allow the intrusion. These can come from the negligence of the publisher of the operating system or certain sensitive software or quite simply that of the user.

Precautions to avoid contamination

At the present time, it is very, very difficult for ordinary people to infest, whether with a virus or a trojan, a freshly installed Windows machine. To protect yourself, all you have to do is respect the following basic rules, which are listed in order of importance:

1 - Disable hiding file extensions, this way you know what type of file you are opening. Rather than hiding what you don't understand, try to understand how extensions work instead.

2 - Never launch (execute) a file received by email, even from a friend, and with an extension other than .jpg, .bmp, .gif, .mpg, .doc (with the reservation of have a version of Word greater than or equal to 97 and by disabling the macros if there are any), .xls (same remark as above). All the other extensions are less frequent and it is better to know them well before performing them spontaneously.

3 - When you download a program from the Internet, do it from a reliable source. Otherwise, use an antivirus that you have updated with the latest definition versions (as a reminder, dozens of viruses are created per week, an anti-virus that has not been updated for 3 months can miss viruses (even an antivirus updated to the latest version is not 100% reliable).

4 - Do not activate file sharing on your machine if it is connected to the Internet (in the case of a PC mini-network). If this is not possible, only share a simple directory in which you put only the files that you want to share with the local network and associate this share with a password.

5 - Use an antivirus and update frequently.

6 - Install a Firewall.

7 - Encrypt your confidential and sensitive data.

8 - Detect abnormal operations (CD-Rom drive that opens by itself, inverted mouse, Internet traffic when you are doing nothing, Internet connection automatically launched when the PC starts up, etc.)