Your system has been infected by one or more Rootkits/Backdoor Trojans.
This allows hackers to remotely control your computer, steal critical system information and Download and Execute files
It's very possible that anything could have been installed on your computer by the remote attacker, including opening other backdoors and installing rootkits.
Also, the capabilities of this particular trojan include keylogging and password stealing so I advise you to take all precautions to safeguard your accounts, passwords, and sensitive data. If you have entered any credit card details or use your computer for financial/banking transactions, you should notify your banks and financial institutions that you may have been a victim of identity theft and to put a watch on your accounts. For more information, please read How to report ID theft, fraud, drive-by installs, hijacking and malware. I also recommend that you change your online passwords for email, banks, etc., immediately -- from a clean computer. It bears repeating to change passwords from a clean computer only.
I strongly recommend that you do a complete reformat and reinstall of your hard disk/s to be sure that the infections are gone. However, before doing so, it is advisable to back up your data to a portable hard disk with nothing in it so that you could easily reformat after or to a CD or DVD. Do not back up to another computer. Also, please take note to back up only data files such as spreadsheets(excel) , word documents, text files, etc. and NOT .EXE (execute), .COM (command), .scr's, .htm, .html, .xml, .zip, and .rar files.
Tutorial on How to backup and restore your data using Cobian Backup
Note: Backing up data with infected files and restoring them to the newly formatted disk will only repeat the infection cycle.
Read here for instructions on How to Reformat and Reinstall your Operating System
After reformatting and reinstalling your system please read these articles:
How to prevent Malware
Danger: Remote Access Trojans.