Trojan Horse

Posted: August 20, 2009 in Virus worm malware


The term comes from the Trojan Horse story in Greek mythology Trojan horses are not self-replicating which distinguishes them from viruses and worms. A Trojan horse, or trojan for short, is a term used to describe malware that appears, to the user, to perform a desirable function but, in fact, facilitates unauthorized access to the user’s computer system. They require interaction with a hacker to fulfil their purpose. The hacker need not be the individual responsible for distributing the Trojan horse. It is possible for hackers to scan computers on a network using a port scanner in the hope of finding one with a Trojan horse installed.


Once a Trojan horse has been installed on a target computer system it is possible for a hacker to access it remotely and perform operations. The type of operations that a hacker can perform are limited by user privileges on the target computer system and the design of the Trojan horse itself.

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

  • Use of the machine as part of a Botnet.
  • Data Theft (e.g. passwords, security codes, credit card information).
  • Installation of software (including other malware).
  • Downloading of files.
  • Uploading of files.
  • Deletion of files.
  • Modification of files.
  • Keystroke logging.

Dangerious trojan attack around the world:


  • The 2009 cyber attack occur and the emergence of the W32 Dozer attack the US and South Korea.
  • Computer worm Conflicker infects anywhere from 9 to 15 million Microsoft server systems running everything from Windows 2000 to the Windows 7 Beta in November 21.
  • Mac Sweeper is the first known rogue software for Mac OS X in January 17.
  • Storm Worm identified as a fast spreading email spamming threat to Microsoft systems in anuary 17. It begins gathering infected computers into the Storm botent .By around June 30 it had infected 1.7 million computers, comprised between 1 and 10 million computers by September.
  • The Samy XSSworm becomes the fastest spreading virus by some definitions as of 2006, October 13.
  • The Zotob worm and several variations of malware are discovered on Microsoft systems. The effect was overblown because several United States media outlets were infected.
  • Santy the first known “webworm” is launched. It exploited a vulnerability in phpBBand used Google in order to find new targets. It infected around 40000 sites before Google filtered the search query used by the worm, preventing it from spreading.
  • Vundo is a Trojan Horse that is known to cause popups and advertising for rogue antispyware programs, and sporadically other misbehavior including performance degradation and denial of service with some websites including Google and Facebook.
  • Nuclear Rat (short for Nuclear Remote Administration Tool) is a backdoor Trojan that infects Windows NT family systems (Windows 2000, XP, 2003).
  • The SQL slammer worm, aka Sapphire worm, Helkern and other names, attacks vulnerabilities in Microsoft SQL Server and MSDE and causes widespread problems on the Internet.
  • The ILOVEYOU worm appears. As of 2004 this was the most costly virus to businesses, causing upwards of 5.5 to 10 billion dollars in damage. The backdoor trojan to the worm, Barok, was created by Filipino programmer Onel de Guzma.
  • The Happy99 worm invisibly attached itself to emails. Displayed fireworks to hide changes being made and wished you a happy new year. Modified system files related to Outlook Express and Internet Explorer on Windows 95 and Windows 98.


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