What is it?
doriot.exe is a file associated with the w32.beagle@mm worm

What does it do?
the beagle worm W32.Beagle.AQ@mm is a variant of W32.Beagle.AO@mm, which is a mass-mailing worm that uses its own SMTP engine to spread. The email attachment is a downloader, similar to Trojan.Mitglieder and Download.Ject.C, which downloads the worm from an external source.

Removal
@symantec