First, a quick definition: a “zero-day exploit” is a piece of malware (either spyware or a virus) that attacks its victims before their software defenses (such as Trend Micro antivirus) know about them. They’re very dangerous because when they hit, you are essentially vulnerable for a period of time until a fix happens, or an appropriate virus/spyware definitions file gets updated.
Critical zero-day exploits have been discovered in Internet Explorer in the past day or two. This means that you are vulnerable if you are running IE for your browsing (still the vast majority of people).
To quote a reputable writer at the weekly news magazine eWeek: “There is no patch available for the vulnerability and, because exploit code has already been released, incident handlers at the SANS ISC (Internet Storm Center) believe a widespread attack is very likely.”
A recommended preventative measure:
Use the Mozilla Firefox browser instead of Microsoft’s Internet Explorer. You can download the latest copy here.
More information about this serious problem is available here.