1. TOPIC: WHAT IS A TROJAN?.<br />-2178059842500<br /> A Trojan horse, or Trojan, is a software that appears to perform a desirable function for the user prior to run or install, but (perhaps in addition to the expected function) steals information or harms the system. <br />The term Trojan comes from the Trojan horse story in Greek mythology of Homer’s Odyssey in which the Greeks give a giant wooden horse to their foes, the Trojans, ostensibly as a peace offering. But after the Trojans drag the horse inside their city walls, Greek soldiers sneak out of the horse's hollow belly and open the city gates, allowing their compatriots to pour in and capture Troy.<br />-32004024511000EARLY HISTORY<br />At the beginning, Trojans were created to cause a huge damage in the computer system. Nowadays, they are used to steal information (bank accounts, files, data,etc.)<br />Trojans have been used as a sabotage weapon by government institutions like CIA.<br />TROJAN PURPOSES<br />Trojans are designed to allow the remote access in a system of an individual. When the Trojan is carried out, the individual can access to the system without permission, and he can do different tasks.<br />Some of the actions that can be done through a remote computer are:<br />*Installation of programs that can contain viruses<br />*Delete or change files<br />*Stealing of personal information (passwords, bank account numbers)<br />*Carried out and ended of processes<br />*Turn off and restart of the system<br />*Erasing of the hard disk<br />WHAT ARE THE CHARACTERISTICS OF THE TROJANS?<br /> Trojans are mainly characterized by three programs: a client, who is the person that sends the instructions to be carried out in the infected PC; a server that is placed in the infected computer, and that receives the instructions of the client, the server carries out them and then returns the information and results to the client; and a server editor, which is used to modify, to protect by using passwords, to link to other programs in order to carry out the server in the moment the program is open. <br />According to the way in which the connection is done between the client and the server, they can be classified in two categories:<br />-Direct connection (the client is connected to the server)<br />-Inverse connection (the server is connected to the client)<br />The inverse connection has more advantages than the direct connection because it can go beyond some firewalls. It is important to know the type of connections because there are more of them, and those other connections do not attack the PC directly but they use an intermediate server to do the process of controlling.<br />WHICH ARE THE WAYS OF INFECTION?<br />Most of the Trojan infections occur when a program that is infected is open or carried out. These programs can be of any type from an installer to pictures. When the program is carried out, it can be seen and it can do tasks normally; but at the same time the Trojan is installed and the process of infection is not visible for the user because any pop up message is shown to warn the user.<br />Some of the most common ways of infection are:<br />-Downloading of network programs<br />-Web pages that contain material that must be carried out on the PC (Activex control and Java programs)<br />-Social network<br />-Attached files in emails <br />401828011620500HOW TO ELIMINATE TROJANS?<br />Some patterns to identify Trojans are: an unknown program that is carried out when the PC is turning on, when files are created or deleted automatically, when the PC runs slowly than usual, errors in the operative system.<br />Also antivirus programs that are designed to delete every type of malicious software; they do not only delete the viruses but also they prevent and avoid new infections. It is recommended to install an antivirus program and also a firewall.<br />