Trojan horse software is software that seems benign or helpful when installed, but soon turns against the computer owner by becoming malicious or providing cover for malicious spyware or worms. Spyware is defined as software that monitors computer usage and reports the usage, or private information on the computer, back to an unauthorized party. This often is accompanied by loss of computer function, and leaves the computer open to further infection by other Trojan horses and viruses.
How Trojan Horse Infection Occurs
Trojan horse software is often installed on a computer because the operator believes that the software is beneficial and trusted. There are four ways this trust is obtained. The first method is by convincing the user that the software will have a benefit, usually by doing something for free or cheaply. The second method is by convincing the user that there is a serious threat that can only be overcome by using the presented software immediately. Third, the user can be lured to a website loaded with the malicious software and gaining user permission to install special viewers or decoders for the website content. The fourth method is by presenting the user with something enticing, such as a cute photo or video that actually contains, or links to, malicious code.
Once a Trojan horse has been installed, it can deliver as a payload many types of malicious software, also known as malware. There are two types of malware that are the most difficult to eliminate. These are spyware and root kits.
Spyware can significantly degrade computer performance and pose a security risk. Root kits are more sophisticated pieces of software that run in the background as long as the computer is on, and is usually undetectable by the casual user. A root kit infection can not only compromise computer security, but can even enable a third-party to take control of the computer completely.
Best Software for Preventing and Killing Trojan Horse Installation
The best software tool against Trojan horses is one that prevents the installation of malware in the first place. There are a few pieces of software that can do just that. One that should be running on every Windows machine, from Windows XP to Windows 7, is Microsoft Windows Defender.
Windows Defender is included in Windows operating systems from Windows Vista and above. It is also a free download for Windows XP. Be sure it is operating and updated regularly on any computer connected to the Internet. Among other things, Defender will alert if a malicious website is being opened, before damage is done.
One of the highest-rated anti-Trojan interception and removal tools is Ad-Aware Free by Lavasoft. This software combines scanning with sophisticated removal tools. This software works in active scanning mode, so Windows Defender cannot be running if Ad-Aware is running.
Another software product known for intercepting Trojan Horse websites, and preventing installation, is Avast Free Anti-Virus. Avast will block sites, and also has excellent modules for spyware and even root kit removal. It is not required that the computer be connected to the Internet at the time of the scan for Trojan horse components, as the database of information is automatically downloaded to the computer on a regular basis. You can disable scanning mode if another virus scanner is running, then use Avast to remove infections.
Trojan horse software is often written to hide from or disable the most common anti-Trojan software. Active anti-virus software such as Symantec Anti-Virus, McAfee and Windows Defender are often defeated and the malicious software is installed without the user suspecting.
Best Software for Removing Trojan Horses and Spyware
If an infection occurs, there are a few pieces of software that can be used to remove harmful spyware. This software should be loaded on your computer before an unfortunate infection occurs. Many of the Trojan horses will block installation of any anti-Trojan software, and even prevent the user from going to a website that hosts removal software.
The first line of defense for Window XP computers is Spybot Search and Destroy. This software will monitor computer activity and report changes to the computer that the operating system allows without needing user permission. For later versions of Windows, this software is not as necessary, as long as the user understands the permissions being granted when asked by the system. Spybot does not have a great success in removing all infections.
Avast and Ad-Aware, both work well to remove malware. However, there is no software that can remove 100 percent of all malicious programs completely. For this reason, it is better to have a good scanning software always running, and at least two more available in case an infection cannot be removed.
The two most advanced malware removers are Trend Micro's HijackThis and MalwareByte's Anti-Malware. HijackThis is powerful because you can examine many aspects of your computer and see exactly where an infection may be lurking. The downside to the software is that inexperienced users may make a mistake cleaning an infection and break the operating system. There are Internet forums set up to guide users in the proper use of HijackThis.
Malwarebyte's Anti-Malware software can run just when you need it to kill an infection. Usually, this software is used in conjunction with HijackThis and another scanner, such as Avast, to remove all malware.
Best Software for Removing Root Kit Infections
Root kits are often installed as part of the payload of Trojan horses. The root kit may prevent the user from operating any other malware removal tool. So the first step in cleaning an infection would be removing the root kit. If the root kit is not detected by Avast or Ad-Aware, there are a few other tools you can use to clean your computer.
Trend Micro makes software called RootkitBuster that eliminates root kit infections. This software is relatively easy to use compared to most, and is quick in operation.
Usually, more than one root kit detection software should be used. The next powerful free root kit remover is Sophos Anti-Rootkit. Using this along with RootkitBuster and Avast or Ad-Aware will eliminate root kit infections.
If these tools do not work, Kaspersky Lab TDSSKiller.exe is another possibility. This recent addition to root kit removers has the ability to kill root kit infections not detected by others. It was written with one family of root kits in mind, so it will not work as a general root kit remover.
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