Virus in attachment?

I got an attachment from a friend and without looking, I tried to open it and Yahoo blocked it. I did some googling on this info and it relates to programming, but noone had any info as to what this is.

File name: Header.dat
File type: application/octet-stream
Scan result: Virus found.
The file attached to this message was infected with a virus that we were unable to clean. You can not download this attachment. Note:
Not all viruses can be cleaned. Please contact the message sender and request that they send you a virus-free version of this attachment.

 

Thanks Halo, I guess since this is an old one that it wasn't high on google. Strange that Symantec had nothing on this. Learnt a good lesson also. Don't open attachments with .dat. extension. Now to disinfect my friend who knows nothing.