WHAT IS A TROJAN?

A trojan (or trojan horse) is a malicious computer program that is disguised as a harmless application or is secretly integrated into legitimate software. It usually carries a destructive payload. A trojan gets silently installed and hides from the user. These parasites are very similar to the regular viruses and  therefore are quite difficult to detect and completely disable. Originally trojans were not intended to replicate by themselves. However, some recent threats have additional components, which enable their propagation. The trojan’s payload varies depending on its author’s intentions. It usually provides the attacker with unauthorized remote access to a compromised computer, infects files and damages the system, drops other dangerous parasites or steals user sensitive information. Navigate to trojan parasites

Newest Trojans

Removal of Dyre virus

September 12th, 2014. What is Dyre virus? Dyre virus is a dangerous trojan horse, which in other sources can be found named as Dyreza or Dyre/Dyreza. Also known as banking malware, this virus has mostly been used for stealing people's financial information and money. If this virus enters computer, it starts... More...

Removal of Ruftar virus

August 11th, 2014. What is Ruftar virus? Ruftar virus is a trojan horse, which is responsible for spreading ransomware viruses, stealing people's private information and initiating other dangerous activities. Also known as Trojan.Ruftar, this threat is responsible for blocking PC system and encrypting... More...

Kronos virus removal guide

August 8th, 2014. What is Kronos virus? Kronos   virus is a malicious program, which is combined of two different cyber threats. It can be said that this virus is a mixture of Trojan and Rootkit. Having powers of these two viruses, Kronos can easily infiltrate your PC unnoticed and hide deep inside... More...

DATABASE OF Trojans PARASITES

Total Trojans parasites in our DB: 2029


# | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

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  • 1440 Trojan November 15th, 2004 | No Comments
    A trojan that can cause some difficulties to the infected system's user. It is believed that its main function...

  • 1648 Trojan November 15th, 2004 | No Comments
    This trojan, created in 2004, can be a dangerous threat to those who doesn't possess a good enough antiviral d...

  • 17th.Inst December 22nd, 2004 | No Comments
    This parasite is a specific representative of various macro-trojans. 17th.Inst usually sneaks into the syst...

  • 1840 trojan August 9th, 2011 | No Comments
    This trojan, originated in 2003, has nothing different from parasites of its kind. It can be a useful tool in ...

  • 1999 Trojan December 8th, 2011 | No Comments
    Although this pest is quite old and obsolete, it is still able to harm several types of old operating systems,...

  • 3B Trojan January 5th, 2005 | No Comments
    Although this parasite is really old and out of circulation, it still is really dangerous trojan, able to dama...

  • 3DStars Trojan June 27th, 2011 | 1 Comments
    There are a wide variety of harmful actions available to this parasite, that's why it should always be treated...

  • 3Trojans February 10th, 2005 | No Comments
    This old joke-trojan, which was written in Quick Basic, doesn't carry any harmful actions. This parasite is on...

  • 3x Backdoor November 15th, 2004 | No Comments
    This backdoor may become a real threat to any system. When 3X Backdoor is run on the specific computer, it giv...

  • 4112 Trojan February 18th, 2005 | No Comments
    Even though this trojan, originated in 2004, didn't cause a lot of problems to many systems, it still is quite...

  • 7Sphere Ttrojan December 23rd, 2004 | No Comments
    This parasite is a trojan, which is always able to damage the infected computer greatly. With the help of 7...

  • Abaxo Trojan January 9th, 2005 | No Comments
    Abaxo Trojan is a specific stealer, which acts by pretending being Bingo form. The main aim of this pest is tr...

  • ABC Trojan November 15th, 2004 | No Comments
    This pest, which was created in 1998, is a typical trojan horse. Once run on somebody's computer, ABC Trojan o...

  • Abebot April 7th, 2008 | No Comments
    Abebot is a backdoor trojan, which is used to lower internet security settings, but recently the popular funct...

  • Absturz 1.0 November 15th, 2004 | No Comments
    This trojan hasn't got many actions available, but some of them, such as hanging the infected computer, mig...

  • Abwiz June 29th, 2005 | No Comments
    Abwiz, also known as Lager, is a trojan that gives the attacker remote unauthorized access to a compromised co...

  • Abwiz.c July 25th, 2005 | No Comments
    Abwiz.c is a trojan that collects system information and sends it to a predefined web server. It also downl...

  • Abwiz.e February 23rd, 2006 | No Comments
    Abwiz.e is a trojan that collects confidential system information and sends it to a predefined web server. ...

  • ABX Trojan September 17th, 2011 | No Comments
    This specific backdoor trojan specializes in searching for the IRC (Internet Relay Chat) client on the infecte...

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WAYS OF INFECTION

Several trojans are able to propagate themselves and infect the system without user knowledge. Others must be manually installed as any other software with or without user explicit consent. There are five major ways unsolicited parasites can get into the system.

1. Many trojans are distributed by e-mail, through file sharing networks and online chats (such as ICQ, AIM or IRC). They arrive in files attached to e-mail and instant messages, come embedded into letters or get downloaded using peer-to-peer applications. These trojans have unsuspicious names and therefore trick a user into opening or executing them. Once the user opens such a letter, message or file the trojan silently installs itself to the system.
2. Some trojans can get into the system using Internet Explorer ActiveX controls or exploiting certain web browser vulnerabilities. Their authors run insecure web sites filled with malicious code or distribute unsafe advertising pop-ups. Whenever the user visits such a site or clicks on such a pop-up, harmful scripts instantly install a parasite. The user cannot notice anything suspicious, as a threat does not display any setup wizards, dialogs or warnings.
3. Trojans sometimes get installed by other parasites like viruses, worms, backdoors or even spyware. They get into the system without user knowledge and consent and affect everybody who uses a compromised computer. Some threats can be manually installed by malicious computer users who have sufficient privileges for the software installation. Very few trojans are able to spread by exploiting remote systems with certain security vulnerabilities.
4. Some trojans are already integrated into particular applications. Even legitimate programs may have undocumented functions like remote access feature. The attacker needs to contact a computer with such software installed in order to instantly get full unauthorized access to the system or take over control over certain program.
5. Lots of trojans infect particular system and software files. The user may receive such files from trusted sources. Once such a file is executed, a trojan quietly installs itself to the system.

Widely spread trojans affect mostly computers running Microsoft Windows operating system. Less prevalent threats are created to work on other popular platforms.

WHAT A TROJAN DOES?

- Infects, corrupts, overwrites or deletes files, essential system components and installed applications, destroys the entire system by erasing all critical files or formatting hard disks.
- Steals bank account details, credit card numbers, login names, passwords, valuable personal documents, identity data and other user sensitive information.
- Tracks user activity by logging names of launched applications, exact time of certain event occurrence and other specific information.
- Logs each keystroke a user types on a computer’s keyboard and takes screenshots of user activity.
- Sends all gathered data to a predefined e-mail address, uploads it to a predetermined FTP server or transfers it through a background Internet connection to a remote host.
- Silently installs a backdoor or activates its own component with the same functionality, which allows the remote attacker to take over a control over a compromised computer.
- Drops other dangerous parasites.
- Performs Denial of Service (DoS) or other network attacks against certain remote hosts or sends out excessive amount of e-mail messages in order to flood predefined computers.
- Installs hidden FTP server that can be used by malicious persons for various illegal purposes.
- Rapidly terminates active antivirus, anti-spyware and security-related software processes, disables essential system services and prevents standard system tools from running.
- Blocks access to some reputable web sites and security-related resources.
- Serves undesirable commercial advertisements and displays pop-ups.
- Degrades Internet connection speed and overall system performance, decreases system security and causes software instability. Some parasites are badly programmed, they waste too much computer resources and conflict with installed applications.
- Provides no uninstall feature, hides processes, files and other objects in order to complicate its removal as much as possible.

EXAMPLES OF TROJANS

There are thousands of different trojans. The following examples illustrate how functional and harmful trojans can be.

The Secup trojan displays fake security related messages. When the user clicks on such a message the trojan opens malicious web site that quietly installs potentially harmful software. Secup  also serves undesirable commercial advertisements.

Dmsys is a dangerous trojan that specializes in infecting various instant messengers and stealing user confidential information. By using its keystroke logging technique, Dmsys easily steals user passwords and captures private conversations. This information is written into a  log file, which is then sent to the hacker.

The Viruscan trojan is disguised as an effective antivirus application, that's why a lot of inexperienced users may mistakenly run it on their computers. Once executed, the parasite starts damaging critical systems components, instead of searching for viruses.

ExeBug is a trojan that infects and corrupts executable files by changing their headers and contents. These actions may lead to improper working of many applications and the system instability in whole. ExeBug usually sneaks into the system from various Internet resources such as insecure web pages or peer-to-peer networks.

Pandora is a very dangerous and extremely destructive parasite, which usually gets into the system from insecure Internet resources, file sharing networks or online chats. It silently works in background waiting for the specified date to run its payload. On the specified date, Pandora attempts to destroy the entire system by formatting the main hard disk or deleting several critical system folders such as Windows or Program Files.

AceBot is a tremendous backdoor trojan, which was designed for performing a lot of different destructive actions. The parasite detects, terminates and totally disables running antivirus software installed on the target computer. AceBot also connects to the IRC network and uses it for giving the hacker a remote control over the compromised system. Moreover, the trojan is able to connect to various malicious servers and download other harmful parasites from there.

HOW TO REMOVE A TROJAN?

Trojans work in the same manner as the regular computer viruses and therefore can be found and removed with the help of effective antivirus products like Symantec Norton AntiVirus, Kaspersky Anti-Virus, McAfee VirusScan, eTrust EZ Antivirus, Panda Titanium Antivirus, AVG Anti-Virus. Some advanced spyware removers, which are able to scan the system in a similar way antivirus software does and have extensive parasite signature databases can also detect and remove certain trojans and related malicious components. Powerful anti-spyware solutions such as Microsoft AntiSpyware Beta, Spyware Doctor, Ad-Aware SE, SpyHunter or eTrust PestPatrol are known for quite fair trojan detection and removal capabilities. Several products such as TDS (Trojan Defence Suite) or TrojanHunter are designed specially to detect and remove various trojans.

In some cases even an antivirus or spyware remover can fail to get rid of a particular trojan. That is why there are Internet resources such as 2-Spyware.com, which provide manual malware removal instructions. These instructions allow the user to manually delete all the files, directories, registry entries and other objects that belong to a parasite. However, manual removal requires fair system knowledge and therefore can be a quite difficult and tedious task for novices.


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