This week at MIT's Computer Science and Artificial Intelligence Lab, Microsoft's current president Brad Smith admitted that--
"Microsoft was on the wrong side of history when open-source exploded at the beginning of the century." "And I can say that about me personally. The good news is that, if life is long enough, you can learn...that you need to change.
"Today, Microsoft is the single largest contributor to open-source projects in the world when it comes to businesses. When we look at GitHub, we see it as the home for open-source development, and we see our responsibility as its steward to make it a secure, productive home for [developers]."
So there you have it... acknowledgement of what the world-at-large has known for quite some time. By its very nature, open source enables anyone to look for and fix security flaws. And since it is peer-reviewed, software is opened up to a larger cadre of inspectors who can quickly detect issues. In fact, many open source solutions are much more secure than proprietary commercial-off-the-shelf products.