what is Trojan horse ??

Trojan horse (computing)

From Wikipedia, the free encyclopedia

Beast, a Windows-based backdoorTrojan horse

A Trojan horse, or Trojan, is 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.^[1] The term is derived from the Trojan Horse story in Greek mythology.

[edit]Purpose and uses

[edit]Adware

A horse may modify the user's computer to display advertisements in undesirable places, such as the desktop or in uncontrollable pop-ups, or it may be less notorious, such as installing a toolbar on to the user's Web browser without prior notice. This can create revenue for the author of the Trojan, despite it being against the Terms of Service of most major Internet advertising networks, such as Google AdSense.^[2]

[edit]Security

Trojan horses may allow a hacker remote access to a target computer system. Once a Trojan horse has been installed on a target computer system, a hacker may have access to the computer remotely and perform various operations, limited by user privileges on the target computer system and the design of the Trojan horse.

Operations that could be performed by a hacker on a target computer system include:

§  Use of the machine as part of a botnet (e.g. to perform automated spamming or to distribute Denial-of-service attacks)

§  Data theft (e.g. retrieving passwords or credit card information)

§  Installation of software, including third-party malware

§  Downloading or uploading of files on the user's computer

§  Modification or deletion of files

§  Keystroke logging

§  Watching the user's screen

§  Crashing the computer

Trojan horses in this way require interaction with a hacker to fulfill their purpose, though the hacker need not be the individual responsible for distributing the Trojan horse. It is possible for individual hackers to scan computers on a network using a port scanner in the hope of finding one with a malicious Trojan horse installed, which the hacker can then use to control the target computer.^[3]

As mentioned earlier on, the term "Trojan horse" was taken from a clever Greek plan described by Homer in the Iliad. After seemingly abandoning the siege of Troy, the Greeks placed armed men inside a huge wooden horse. The horse was welcomed into the city by the Trojans, who believed it was a symbol of peace; they slept while the Greeks exited the horse and opened the gates allowing the Greek army into Troy, conquering the city.

[edit]Current use

Due to the popularity of botnets among hackers and the availability of advertising services that permit authors to violate their users' privacy, Trojan horses are becoming more common. According to a survey conducted by BitDefender from January to June 2009, "Trojan-type malware is on the rise, accounting for 83-percent of the global malware detected in the world". This virus has a relationship with worms as it spreads with the help given by worms and travel across the internet with them. ^[4]

[edit]See also

§  Cyber spying

§  Dancing pigs

§  Exploit (computer security)

§  Industrial espionage

§  Malware

§  Principle of least privilege

§  Privacy-invasive software

§  Reverse connection

§  Rogue security software

§  Secure computing

§  Social engineering (security)

§  Spam

§  Spyware

§  Timeline of computer viruses and worms

[edit]Notes

[edit]References

1.    ^ What Is the Difference: Viruses, Worms, Trojans, and Bots? - Cisco Systems

2.    ^ "AdSense Terms and Conditions". Retrieved October 5, 2010.

3.    ^ Jamie Crapanzano (2003): "Deconstructing SubSeven, the Trojan Horse of Choice", SANS Institute, Retrieved on 2009-06-11

4.    ^ BitDefender.com Malware and Spam Survey

§  Carnegie Mellon University (1999): "CERT Advisory CA-1999-02 Trojan Horses", Retrieved on 2009-06-10.

[edit]External links

§  Trojan Horses at the Open Directory Project

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