Recently, it was uncovered that Lenovo was loading software onto its laptops that was using a compromised security certificate and Microsoft reacted quickly to update Windows Defender



From Neowin:

This week has been one that Lenovo would love to forget after it was discovered that software they were loading onto laptops opened a huge security hole in Windows. The adware, called Superfish, placed its own security certificate on your machine and intercepted encrypted traffic to inject advertisements, also known as a man-in-the-middle attack.

That's the bad news and Lenovo is trying to backtrack and repair its brand image as the company has taken a serious reputation blow following this incident. Because of the nature of what Superfish did, it is a security threat to Windows and this is where Microsoft has stepped in.

  Microsoft updates Windows Defender