Q:

How can someone get my CLSID?

I just got a call from a guy telling me he was Microsoft IT support. He told me to go to a suspicious website and download an executable there.  Totally did not give him the satisfaction and trolled him. After making him wait for my "download" to finish (just me bs-ing the progress by single percents), he gave himself away cursing and saying he wasn't IT support.  
Anyway, he tried to prove that he was Microsoft IT support by telling me to run "assoc" in command prompt and he matched the value for the CLSID that was near the bottom of the listing. Is that value accessible to the outside or is my computer compromised?

A:

CLSID is unique to an application, not to your computer.  See here for that particular scam methodology:
http://www.welivesecurity.com/2011/07/19/support-desk-scams-clsid-not-unique/
Was it ZFSendToTarget=CLSID{888DCA60-FC0A-11CF-8F0F-00C04FD7D062} ?
Note, they may have called your CLSID your "Consumer License ID" but it's actually a "Class Identifier"

