Very recently , the Mumbai Police website was in the news.

The Mumbai Police, the custodians of Mumbai citizen’s security, were attacked by a Trojan Horse.

http://www.dnaindia.com/mumbai/report_mumbai-police-website-hijacked-by-malicious-software_1293911

Now what is a Trojan Horse?

The original Trojan Horse comes from Greek mythology. Youngsters of this generation may relate to this because of the movie Troy starring Brad Pitt. It has been aired on STAR Movies umpteen times. The Greeks were unable to break down the impregnable walls of Troy , despite having numbers on their side. In their despair, they came up with the shrewd stratagem to create a statue of a horse, a gigantic one, with the remains of their ships. The Trojans accepted it as a sort of mollification gift for the Gods. And dragged it inside their impregnable walls. Little did they know, that the wooden horse housed a few Greek warriors. These warriors , under the cover of darkness, opened the gates of Troy to let in the Greek army and that was the end of Troy as we know it.

But a Trojan Horse, in the context of computers, is a completely different ball-game. It’s called a Trojan Horse because it employs a similar stratagem. It appears harmless but once it’s on your computer, it can either attack your computer or lie in wait to cause havoc at a pre-determined time or on a trigger caused by some event.

For more information, http://en.wikipedia.org/wiki/Trojan_horse_(computing)

Most Anti Virus packages are good enough to catch these Trojan Horses.

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 wild".^[2]