The primary role of Trojan horses is to perform various actions that were not explicitly allowed by the user. This can include, but is not limited to:
· Data Modification
o Computer performance
o Network performance
· Personal Data Collection
Classifications of Trojan Horses
Exploit: Exploit Trojans are applications that seek security vulnerabilities of software and operating systems already installed on a computer for malicious intent.
Backdoor: These are created to give an unauthorized user remote control of a computer. Once installed on a machine, the remote user can then do anything they wish with the infected computer. This often results in uniting multiple backdoor Trojan-infected computers working together for criminal activity.
Rootkit: Programmed to conceal files and computer activities, rootkits are often created to hide further malware from being discovered. Normally, this is so malicious programs can run for an extended period of time on the infected computer.
DDoS: A sub sect of backdoor Trojans, denial of service (DoS) attacks are made from numerous computers to cause a web address to fail.
Banker: Trojan-bankers are created for the sole purpose of gathering users’ bank, credit card, debit card and e-payment information.
FakeAV: This type of Trojan is used to convince users that their computers are infected with numerous viruses and other threats in an attempt to extort money. Often, the threats aren’t real, and the FakeAV program itself will be what is causing problems in the first place.
Ransom: Trojan-Ransoms will modify or block data on a computer either so it doesn’t work properly or so certain files can’t be accessed. The person disrupting the computer will restore the computer or files only after a user has paid a ransom. Data blocked this way is often impossible to recover without the criminal’s approval.
Downloader: These are programmed to download and install new malicious programs onto a computer, which usually includes Trojans, spyware, adware and/or viruses.
Spy: This type of Trojan horse will be invisible to the user while he or she goes about their daily routines. They can collect keyboard data, monitor program usage and take screenshots of the activity performed on the computer.
Additional Types of Trojans: Further types of Trojans include those that steal application and game login information, scour and collect email addresses, send text messages from mobile devices to 1-900 numbers among other effects.
How to Avoid Trojan Horses (And Malware in General)
Since Trojans are initially installed by an unaware user, the easiest way to avoid getting a Trojan horse is to not install software from unknown sources like piracy websites or from unsolicited emails.
Trojans are notoriously difficult to remove, but there are a number of free anti-virus and anti-malware programs available that, when used in conjunction with each other and through due diligence, will eventually help users eliminate all the various malicious software that a computer may have acquired over time.
Some of the more popular free scanners include:
For those who still can’t remove the malicious software from their computers, a program called HijackThis will create a log of everything running on a machine which can then be uploaded to support sites for advanced assistance.