(Trojan-Downloader.Win32.IstBar.nj, Win32/Istbar.BN!Trojan, W32/Istbar.NJ!dldr)
Possible pressence of the IstBAR toolbar in Internet Explorer browser and/or other malware.
Please let BitDefender disinfect your files.
Marian RADU, virus researcher
This malware is an online installer created with NullSoft Installer.
Upon execution it announces the user that it will install a toolbar for "Internet Explorer" but no "Cancel" option is present, only one "Agree" button. If pressed, an executable file from http://www.ysbweb.com/ist/softwares/[removed] will be downloaded, saved as "gkey.dll" in the temporary folder, and executed as an ".exe".
In fact, the downloaded file could be either a toolbar, another trojan downloader or even other malware.