...mostly.
Verisign (& presumably the rest of their group - Thawte, Geotrust) and Comodo didn't issue it - their systems never allowed null characters in subjects.

Some evidence so far (as this isn't the first time it's come up, just the first to be published like this and as with so much at Blackhat, sensationalised) points to Globalsign as the issuing CA, although I'd be surprised if they hadn't fixed it by now.

The US is a more violent country in general than many other industrial nations, guns have nothing to do with it.

No, I think guns have a lot to do with it. As Eddie Izzard said - you can't kill people walking up to them and shouting 'bang!'. It just doesn't work.
And don't go blaming your 'violent country' or 'violent past' - it's bullshit.

Look at the statistics. People died from bullets coming out of guns. The reason doesn't really matter...less guns, less fatalities from shootings.

Surely not too hard for you to understand, eh?