Today backdoor Trojans are the most widely spread and dangerous Trojans of all times as they operate as remote administrative utilities that have control to open your system to infected machines through the Internet or LAN. A backdoor Trojan can delete data on its own from your system, display unwanted notifications or errors, launch or send/receive files to other machines, reboot your computer and steal away your personal details such as financial account details and other confidential details. It is said that backdoor Trojans is a whole package of what other Trojans can do. 

Types of Backdoor Trojans
NetBus
This backdoor Trojan hides itself onto your system and opens your system to infected machines without your knowledge. It steals files, damage newly installed softwares and is known as the hidden hacker’s remote administration utility as it controls every single action on your computer. 

Agobot.gen.
Agobot.gen. allows the virus writer to remotely control a victim’s machine through IRC channels. It copies itself onto the Windows Directory with many random names and then registers itself in the system registry auto-run keys. On being installed and registered, it connects to various IRC servers, the list of which is imbibed in its body. It then allows the virus writer/hacker or master to launch and transfer files to the victim’s machine when connected with the IRC servers. 

Win32.BO.a
Also known as the Back Orifice Trojan, it allows the creator to control a computer across TCP/IP connection using a graphical user interface or console. This type of virus is very common and dangerous as it performs certain weird actions such as:

• Log off a current user
• Cause the computer to free or lock up
• Search for a specific file
• Open and redirect other TCP/IP sockets
• Compress or decompress files and folders
• Decrypt user passwords and send them across to the creator
• Play sound files on its own
• Store keyboard inputs of the user
• Send details such as installed drives, space available with drives, processor type, memory size, Windows OS version etc
• Connect to some network resources
• Access system registry and much more..

Win32.AckCmd
This backdoor Trojan has two components namely the server and client written in Visual C++. The server component is installed at the victim’s end while the client side is installed on the hacker’s end. This virus uses ACK packets to transfer data to and from the victim machine to the master. Owing to this nature, the virus can transfer information even while the victim machine makes use of a personal firewall. 

Win32.Afcore.q
Afcore.q virus installs as a Windows application file that has a size of 110 kb and it appears as a .dll file.  This virus installs itself into the system 32 catalog and forms a combination of arbitrary symbols. A special utility that can remove this virus from the file stream can be used to get rid of this backdoor virus. 

Win32.Delf.akw
Written in Delphi, this backdoor virus is a Windows PE exe file with a size of 245760 bytes.  It provides the master or virus writer access to the victim’s machine via Telnet and allows sharing, transferring of files and remotely managing the victim’s system.     

Win32.Haxdoor.o
This backdoor virus spreads through the Internet. The virus writer makes infected messages that carry code of conducting mass mailing and other such malicious activities on the victim’s machine. This virus also opens port 16661 of the victim machine for the hacker/virus maker to connect with the system. This virus also steals the victim’s passwords and confidential details to send it to the creator of the virus.

Win32.Zomby.b
This virus is a Windows PE EXE file that is only 16,896 bytes in size. Written in Visual C++, it is copied to the Windows system directory as ‘Kernl32.exe.’ It opens a TCP port for the creator to connect with the victim machine. This virus downloads and deletes files, directories; get passwords and active connect ion of the users, get system information and much more.
These are just a few of the backdoor viruses discussed. There are more than 70 backdoor viruses that are present. Though scanning your PC with the latest anti-virus programs can help you prevent such backdoors installing on your computer, you still need as virus removal expert who can suggest you ways and means of dealing with such virus attacks.
Ask PC Experts can assist you in removing backdoor Trojans, installing effective firewalls, updating critical operating system patches and securing your PC with advanced system protection. They offer annual PC protection plans and incidental plans for individuals and small businesses along with installations of 50+ system utilities, e-mail back up and advanced system optimization.