It turns out that that Blaster removal tool I mentioned yesterday only appears on Windows Update for computers which have some kind of trace left on computers of the virus (either having been infected in the past, or actually being infected). Apparently the computer I’ve been using at work recently, from which I discovered this, had been “Blastered” at some point. Which isn’t inconceivable since, for various reasons, I haven’t been running anti-virus software on it.

Of course, this means that while Windows Update is being helpful, it’s also scanning machines for more than just their OS version and patch levels. I hadn’t thought that Microsoft was supposed to be doing that.