HB Blog 57: Trojan Horse Invades.

Viruses, worms, Trojans, and bots are all part of a class of software called malware. Malware or malicious code (malcode) is short for malicious software. It is code or software that is specifically designed to damage, disrupt, steal, or in general inflict some other “bad” or illegitimate action on data, hosts, or networks.

Trojan horse malware is one of the most famous and deadly virus. It is named after the ancient story in which Greeks used horse ship build of wood to invade city of troy. Similarly this kind application is seen in this malware. A Trojan horse, or Trojan, in computing is a generally non-self-replicating type of malware program containing malicious code that, when executed, carries out actions determined by the nature of the Trojan, typically causing loss or theft of data, and possible system harm. A Trojan often acts as a backdoor, contacting a controller which can then have unauthorized access to the affected computer. A Trojan may give a hacker remote access to a targeted computer system. Operations that could be performed by a hacker, or be caused unintentionally by program operation, on a targeted computer system.The main difference amid a normal computer virus and a Trojan horse is that it is not specifically developed for spreading themselves. In its place Trojan horse virus is downloaded either as an infected file from internet, or as payload of some other virus. This virus is capable of stealing end-user information and downloading other malware to a computer too. To fight with this treacherous virus, your computer is equipped with firewall and you can also install antivirus software in your system. However, an antivirus is not always effective against Trojan horse, so at that instance the way out of the problem is to remove Trojan horse virus manually.After recognizing a file infected with Trojan horse, it becomes easy to remove it. Usually, your system will give you DLL error, which is associated with Trojan attack.

Few notable Trojan horses malware are as follows:
    Netbus Advance System Care(by Carl-Fredrik Neikter)
    Subseven or Sub7(by Mobman)
    Back Orifice (Sir Dystic)
    Beast
    Zeus
    Flashback Trojan (Trojan BackDoor.Flashback)
    ZeroAccess
    Koobface
    Vundo