The file names iStealer.exe, csrss.exe, svchost.exe, ewUV4DJTQ6.exe, firefox.exe, iS 6 Legends.exe have appeared in an virus analysis report. You can see it on this link
It installs a component of backdoor Trojan Bifrose or BiFrost. It connects to remote hosts. It can download harmful files from the internet. A good firewall can detect harmful activities and prevent them. Some good freeware are ZoneAlarm Free Firewall, and Comodo Internet Security Free Edition (you can choose to install just the firewall from their security suite)
It infects Internet explorer browser. It attaches a keylogger with Internet Explorer. That will steal your user ID and passwords. So do not use Internet explorer until the virus is removed.
It creates the files iStealer.exe, csrss.exe, svchost.exe, ewUV4DJTQ6.exe, firefox.exe, iS 6 Legends.exe on the infected computer that you need to search and delete. You should end running processes named iStealer.exe, csrss.exe, svchost.exe, ewUV4DJTQ6.exe, firefox.exe, iS 6 Legends.exe from Task Manager. And also remove the file's entries from windows start-up.