In response to the Win32/Popureb.e threat being propogated on the internet, Symantec's response was:
The Popureb family is nothing new and we have seen variants of this family for months. Most are detected as Trojan.Fakeav, but it appears this variant that MS has dubbed as “E” might be a little more severe. Everythingthat we have read says it does nothing that Trojan.Tidserv doesn’t already do.
In order to provide specific info on this what MS is referring to in their “E” variant, Symantec need to get the code from them. To that end Symantec has already asked them for it and are awaiting it from them.