Virus:Win32/Ramnit.A infects .HTML files with .HTML or .HTM extensions. The infected .HTML or .HTM files might be detected as Virus:VBS/Ramnit.A.
Allows backdoor access and control / Connects to remote server
Virus:Win32/Ramnit.A creates a backdoor by connecting to a remote server. Using this backdoor, a remote hacker can perform any number of actions, including downloading and running files on the infected PC.
See the description for Worm:Win32/Ramnit.A for more details on how the malware downloads and runs files.
The virus creates a default web browser process (which you won't be able to see) and injects code into it.
It might do this as a way to avoid detection and make it more difficult to remove from an infected PC.