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Trojans are impostor files that take their name from the infamous penetration of Troy by the Greek army. Hiding inside a giant wooden horse, the Greek army was brought within the walls of Troy by its own inhabitants while disguised inside a peace offering. Similarly, Trojan files often appear to be desirable but are actually dangerous and destructive. Like the infamous Trojan horse of Greece, many computer Trojans seem benign, or even useful, hidden inside protective anti-virus software.
Unlike viruses and worms, Trojans do not self-replicate. Whereas viruses can be spread unknowingly through the exchange of files on disks or other portable data devices, in order for Trojans to spread they have to be opened or downloaded and executed by a specific user command, most often an email attachment or similar data file.
While most viruses execute malicious code that infects and destroys the system, Trojans establish what is known as a ‘backdoor” or a “trapdoor” through which the Trojan can send personal information extracted from your computer to a third party system.
Trojans generally have two parts, a client and a server: the client refers to the system used by the hacker, and the server to the victim’s system. Once opened, the client connects to the server and is then able to run programs or extract data. The server sends its IP address to the client allowing it access to the system. Once this connection is established the client can issue commands to the server that are executed on the victim’s computer.
Once the connection is made between the server and the client the hacker is able to run tasks secretly on the victim’s computer and enable total remote access of the computer by the third party known as RAT (remote access Trojan). In this way server computers are used to transmit illegal data or malicious code through the IP address of the unsuspecting victim.
Rather than simply run destructive code like a virus, a Trojan enables a hacker complete access to your computer and its contents. The more sophisticated the hacker the more serious the risks become, and the more difficult it may be to recognize the infiltration. An immature hacker might take remote control of your system for nothing more than a joyride.
The hacker will not be stealth and will make his or her presence known by opening and closing your CDROM drawer, inverting or flipping your computer screen, changing your screen saver or desktop, or playing media files from your computer. When the hacker is in control of the system there is no way to stop such events. More dangerously, even the immature hacker can access personal data saved on your system and make it generally available, release it through mass emails and chat functions.
Still, the more sophisticated hacker is not interested in wreaking havoc for the victim and prefers to remain undetected. Controlling the system remotely the hacker can access private and sensitive information stored on your system, run programs and scans through your system without your knowledge, your computer might turn itself on and dial up the modem by itself allowing the hacker full control of the system. By saving your credit card information the hacker may begin making charges to your account and establishing additional accounts based on your information.
There is antivirus software that specifically looks for and eradicates Trojans.
