Still using Internet Explorer? If so, you should check your Windows Updates to make sure that you’ve received a new IE9 patch that has been rated as "critical" by Microsoft.

The patch is designed to protect against 8 specific vulnerabilities discovered in Microsoft’s web browser. While the details of each are not revealed, the company did state on its Security TechCenter blog that the worst vulnerabilities allowed for remote code execution. If a user with administrative rights visited a site that takes advantage of this exploit, an attack could do significant damage before the user realizes something is wrong.

Solving this threat required that Microsoft modify "the way that Internet Explorer handles objects in memory and the way that Internet Explorer allocates and accesses memory." Thus, the patch.

If your computer is set up for automatic updates, the patch should be downloaded and installed to your computer automatically. You can check to see if the update was installed by opening Windows Update and then clicking on "View Update History." The update will likely be listed as a "Cumulative Security Update for Internet Explorer 9."

Users who have for some reason turned off automatic updates can install it by opening Windows Update and browsing to the Important Updates. Select the update related to this threat and then click the install button. This will install the IE9 related update only.

Source: CNET