what is trojan horse in computer?

A trojan horse is a form of computer malware which appears to be a harmless program but infects the system, affecting the normal functionality. The name is derived from the renowned legend of Troy’s wooden horse because it implements the same method to operate and survive. It can alter the settings of a system or cause unusual system activities even if the computer is idle or on standby mode. It is difficult to detect the existence of a trojan horse malware in a computer system because it is disguised as an innocuous program file. The term trojan horse in the field of computing was coined by the US Air Force in its report on identified vulnerabilities of the defense computer systems in the year.

Trojan Horse Programs Are Not Viruses
Trojan horse malware is sometime incorrectly termed as a virus. These programs are not computer viruses. A computer virus can be transferred from one host program to another, all it requires is an active and vulnerable host, an operating system. A trojan horse cannot be transferred to a system without aid from the user himself. Trojan horse is concealed in a program while appears to be harmless, the program must be downloaded and installed by the end user in order to let a trojan horse sneak into the system and remain hidden.

Difference Between Trojan Horse and Computer Worm
Trajan horse computer malware is often confused with computer worms, another kind of malicious software which can infect a computer and deteriorate its performance. While there is one similarity between trojan horse programs and computer worms that these are stand-alone programs and do not need a host program like viruses, the two kinds of malware are not the same. Computer worms propagate by self-replicating. These clone to vulnerable systems through networks, local area or wide area. The Trojan horse programs cannot reproduce on their own and require a user to download and install a seemingly harmless but malicious trojan horse to their system themselves.

What Threats Does a Trojan Horse Poses?
A trojan hose poses various kinds of threats to computer security. Vulnerability of an unprotected computer against a Trojan horse malware is quite high for it cannot be identified easily unlike a few other forms of viruses, for example, adware. The threats which a Trojan horse computer malware poses are enlisted below:

• It can create a backdoor opening for a hacker to take control of your computer system compromising complete computer and data security. The hacker can then seize control of the entire computer system, control its functionality and access user information which can be used to commit fraud, theft or any other kind of cybercrime.

• Some types of trojan horse are programmed to record keyboard usage to leak passwords or other kind of data.

• A trojan horse malware may be a professionally coded spyware which would activate only if the user performs a particular task, accesses online accounts or uses credit card details etc. It would record all information and propagate it to an external channel, a hacker.

• It may be programmed to download a certain computer virus, spyware or any kind of computer malware upon a specific command from the user.

• Trojan horse may be used to alter settings, activating camera or voice recording or performing any other function which breaches security and privacy of the user.

How Does a Trojan Horse Work?
A trojan horse works exactly the way it was used according to the Greek legend in which soldiers were transported into the city-state inside a horse-shaped wooden cell which the people mistook for a real animal. In the darkness of the night, the soldiers came out and opened the city gates and the siege was laid. A Trojan horse computer malware may be a document attachment in an email or a program file in a software package, a game or some other application. Since it appears harmless, the user downloads or installs it on his computer. A trojan horse malware is usually a time or logic-based program which does not activate until a certain time or works only when a specific operation is performed, until then it remains inactive or on stealth mode and disguised as a harmless file stored on the system. Once activated, it performs the task it has been programmed for, hacking, creating backdoor channel, downloading a virus or whatsoever.

It is almost impossible to detect a trojan horse because it has been designed to deceive a common user. It looks like a harmless file which trick the user in downloading or installing the malicious program on the computer. Since these programs are time-based or logic-based so these do not make any immediate changes to the system and remain undetected. Even upon activation, these programs remain hidden in the storage because they look like regular files. It is almost impossible for an ordinary user to detect the existence of a trojan horse in a normal looking file. It is important to equip a computer with a strong anti-malware software which can detect a trojan horses and keep the system protected.

An unprotected computer is highly vulnerable against trojan horse programs not because these can sneak into the system on their own but because these have been designed to deceive users and tricking them into downloading and installing them. Only a strong and comprehensive antimalware software can provide necessary protection and prevent the Trojan horse from being downloaded and installed on a system.

If a system is working unusually and the user suspects the existence of a trojan horse, the only possible way to detect and remove it from the system is using a comprehensive antimalware software which can scan the system thoroughly, identify a trojan horse and remove it. Some of the top-rated antimalware software like Avast, MSRT by Windows, AVG etc. provide trojan horse removal tool for free included in their comprehensive PC protection software.

A trojan horse is a sort of computer malware which is hidden a normal looking file, it requires the user to download it to the system himself by tricking him. A trojan horse is almost impossible to detect given the fact that it is disguised. Antimalware software which can detect and remove trojan horse malware should be used for trojan horse can breach computer security and compromise user’s privacy.