Upload the file to www.virustotal.com and when you have the result, copy the URL in the addressbar and post it HERE
also upload to virus(at)avast(dot)com in a password protected zip.file with the password in the mail
Send the sample to virus (at) avast (dot) com zipped and password protected with the password in email body, a link to this topic might help and undetected malware in the subject.
Or add to the avast chest and send from there:
avast 5.0 - Send the sample to avast from the chest as a Undetected Malware:
Open the chest and right click in the Chest and Add, navigate to where you have the sample and add it to the chest (see image1). Once in the chest, right click on the file and select ‘Submit to virus lab…’ complete the form and submit, the file will be uploaded during the next update.
avast 4.8 - Or you can also add the file to the User Files (File, Add) section of the avast chest (see image2) where it can do no harm and send it from there. A copy of the file/s will remain in the original location, so you will need to take further action and can remove/rename that.
Send it from the User Files section of the chest (select the file, right click, email to Alwil Software). It will be uploaded (not actually emailed) to avast when the next avast auto (or manual) update is done.