If you have Internet Explorer versions 9 or 10 you are not affected by this latest exploit. But if you are running an older version of their popular browser you should use the "Fix it" tool Microsoft released on Monday.
According to the Microsoft Security Advisory (2794220) the vulnerability is a hole in the browser that allows hackers to exploit a 0-day attack. This type of attack allows an attacker to remotely execute code on your systemCriminals began using this specific exploit right before Christmas in a "watering hole" attack stemming from the Council on Foreign Relations (CFR) website. After the initial compromise occurs malware is brought in and used against unsuspecting users. The vulnerability was discovered soon afterwards and Microsoft issued the security advisory.
This news is especially back for all the Windows XP users who cannot upgrade to either Internet Explorer 9 or 10. So there is a temporary fix available until a patch is released. Or you can use another browser such as Firefox.