What is Trojan Horse?

Trojan horse is a backdoor. The hacker via the Trojan Horse to collect some information from computer, such as credit card numbers, bank account. Hacker can control the computer, such as print screen, key monitor, send some commands to the computer. The important things is the hacker can transfer another version of Trojan Horse to the computer, the hacker can make sure the Trojan Horse keep working. To guarantee the anti-virus software cannot easily to fully clear it.

Criminal case

In 2012, a Trojan Horse calls "Marauder", it steal a lot of QQ accounts. Since the users download some cheat programs, but these cheat programs attach with the Trojan Horse. When the user execute the program it will execute the Trojan Horse immediately. The computer become start, the Trojan Horse will auto run. Hacker can view some contact list by the chatting software, for example QQ. Moreover, social networking sites it is contain various information, for example Facebook. Hacker can gain some information, such as E-mail address, contact numbers. Lastly, hacker can attach some Trojan Horse files, it is send by infected computers. To form a large network.

These user was steal the QQ accounts and virtual currency,  this Trojan Horse can force the verify system and changed the account password. The account holder cannot login the QQ account. These account was used to sell some virtual currency to gain the money.

Solution

Suggest the user install the anti-virus software and keep update the virus pattern. if you are not the latest version, the anti-virus software may not properly detect the signature.

References: 
1. "Trojan horse". n.d. In Wikipedia. Retrieved March 18, 2014, from http://en.wikipedia.org/wiki/Trojan_horse_(computing)

2. "Malware signature". n.d. In Wikipedia. Retrieved October 8, 2012, from http://zh.wikipedia.org/wiki/%E7%89%B9%E5%BE%81%E7%A0%81