Thanks, Richard. Unfortunately, when I ran the patch it quit when it discovered that I had SP1, saying that it was only for XP not upgraded to SP1. I presume from that that SP1 includes the fix. (Sorry, I should have said at the start that I had SP1.)
I read the article. It was mostly above my head, but I did note that it mentioned UPnP and associated ports 1900 and 5000.
GRC has a few downloadable utilities. One of them switches on and off UPnP. I've used that in the past to disable UPnP on Gibson's recommendation for security reasons. When I toggled it just now to enable UPnP it opened 5000, as you'd expect, and then closed it again when I asked it to.
I cannot see what's happening to 1900, but 1024 remains open all the time. Here's what Gibson's port scanner says about 1024 when it found it open on my PC:-
One or more unspecified Distributed COM (DCOM) services are opened by Windows. The exact port(s) opened can change, since queries to port 135 are used to determine which services are operating where. As is the rule for all exposed Internet services, you should arrange to close this port to external access so that potential current and future security or privacy exploits can not succeed against your system.
You can try it for yourself (if you haven't already) at
https://grc.com/x/ne.dll?rh1dkyd2 Just go to the bottom of the page and click in turn Common Ports and All Service Ports and se your results for yourself.
Edited to add:-
You may not be able to go directly to that page using the above link for security reasons. If necessary navigate from Gibson's Shields Up page at
https://grc.com/x/ne.dll?bh0bkyd2. Use the ports links in the Shields Up Services table halfway down the page.
End of edit
Of the first 1056 Internet ports, the only one I have open is 1024. It used to be "stealthed" - ie invisible to the outside world. Its changed status to "open" worries me.
Cheers
AA