The worm is designed to spread via .com, .cpl, .exe, or .scr file attachments in email messages and will likely contain one of the following subjects:

Re:
Re: Hello
Re: Hi
Re: Thank you!
Re: Thanks

The worm is designed to "spoof" or to fake the from address of an e-mail so that it looks like the e-mail is coming from someone else. As a result, it is probable that the e-mail sender is someone you're familiar with or from whom you've received email from previously.