What Is a Trojan Horse Agent?

Trojan horse programs were named after the wooden horse built by ancient Greek soldiers to capture the city of Troy.

Identity theft has reached epidemic levels. Infecting computers with a Trojan horse agent is one way thieves can steal your identity. Learning how to prevent these attacks can save you money and time and offer you peace of mind while you're surfing the Web.

Identification

A Trojan horse is a term used to describe a malicious program that masquerades as something else to get users to download or open a file. A Trojan horse agent refers to a specific type of Trojan. The word "agent" is typically followed by a unique name or number. Trojans work on the client-server model: The file is downloaded to the victim's computer (the client); the Trojan then sends information back to the attacker's computer (the server).

Types

Trojan horses are classified as types according to their purpose. Among the most common versions are backdoor, downloader, infostealer, wingate and keylogger Trojans. Backdoor Trojans create a "back door" into the victim's computer, allowing remote access by the attacker. Downloader Trojans download other malicious software. An infostealer Trojan searches the computer for sensitive information and sends it to the attacker. The wingate Trojan acts as a proxy server, allowing the attacker to appear to be using the victim's computer to access other sites, usually illegal. The keylogger type monitors keystrokes, searches the data and sends, for example, credit card numbers used to make online purchases to the attacker.

Methods of Infection

Trojan horses commonly infect computers by sending attachments in emails or links in instant messages, tricking the user to download a file or other malicious or infected software, or through the use of drive-by downloads. Drive-by downloads occur without the user's knowledge or consent. For example, a mouse moving over a specific spot on a Web page may activate a script that starts an undesired download.

Protection

Don't open email attachments or click on links in chats from people you don't know. Be suspicious of free software or pop-ups on websites that advise you that your computer is infected and tell you to click a button to run a scan. Invest in a credible antivirus program from a reputable company (see Resources). Configure the antivirus software to start with the operating system and enable the automatic updating feature. Refer to the "Help" files of the antivirus program for assistance.

References

• Symantec: Trojan Horse
• Top Bits Tech Community: Trojan Virus

Resources

• F-Secure: Dealing With Fake Security Products
• AV Comparatives: Independent Tests of Anti-Virus Software
• McAfee: Search McAfee Avert Labs Threat Library
• Anti-Spyware Coalition