Trojans or Trojan horses

 

What does a Trojan infect?

Although Trojans are similar to computer viruses, they cannot be considered as viruses. Trojans try to pass themselves off as harmless programs and get into computers through any of the usual means of propagation. The user, believing this is a useful application or an interesting file will be tempted to run it or open it. If this happens, the Trojan will install a damaging program on the system.

 

How does a worm infect and propagate?

Trojans ‘drop’ or include programs in infected computers through any of the usual means of propagation. These programs carry out a series of actions aimed at obstructing the user’s work, causing damage to the system and stealing information.

 

How does a Trojan work?

A Trojan may have entered a computer although it has not yet carried out any actions. Trojans wait for a certain condition to be met - the trigger condition - to start acting. When the trigger condition is met, the Trojan deletes files, eliminates hard disk information and opens security holes (backdoors), which make the system vulnerable to attack from malicious users.

 

The main objective of Trojans is to access certain communication ports (access points in a computer or means through which information is transferred –inbound/outbound – from the computer to the outside and vice-versa) in order to leave them open and accessible from the outside (their name, Trojans, comes from the Trojan Horse in Greek mythology). As a result, an attacker could access all the information stored in the system infected with a Trojan through a connection established from another computer in a local network or connected to the Internet and carry out a number of actions on it.

 

For more information about viruses consult the Virus encyclopedia on the Panda Software website (www.pandasoftware.com/virus_info/encyclopedia).