There are times when companies don't do enough to protect themselves from cyber threats. And there are times when they can do little to stop a threat. That's why Microsoft's latest move has proven so important.

In a quiet move on Monday, Microsoft acquired corp.com, a website that for 26 years had been owned by Wisconsin-based Mike O'Connor. KrebsOnSecurity, which spoke to O'Connor, first reported the news. O'Connor told the security site that Microsoft acquired the domain for an undisclosed sum. He had previously listed it for sale at $1.7 million, according to the report.

So, what would Microsoft want with a seemingly useless website that it may have paid millions of dollars for? Believe it or not, corp.com is extremely important to the safety and security of companies across the globe. And it's a good thing Microsoft just acquired it.

Unbeknownst to most, many companies have inadvertently been sharing all kinds of sensitive information with corp.com. According to a study obtained by KrebsOnSecurity, hundreds of thousands of computers around the globe still hit corp.com to try to log in to corporate internal networks or access a company's file storage. Along the way, they share passwords, e-mail addresses, and other content you don't want malicious hackers to have.

Worst of all: the flaw is decades old.

In old versions of Windows, "corp" was the default setting for the Active Directory domain companies could use to access network information. And if they didn't change the "corp" setting to something unique and related to their business, they were running the risk of employees outside the network trying to access files via the internet through corp.com.

Of course, this is extremely technical, but the gist is this: if a company never changed the default setting for how employees access resources on the internal network, and if employees tried to remotely access those resources without being on the internal network, there was a good chance their machines were routing private information through corp.com.

When O'Connor put up corp.com for sale, it paved the way for anyone to get access to the domain and spy on the traffic flowing through it from hundreds of thousands of computers. By acquiring the domain, Microsoft safeguarded that data.

Of course, this isn't a new flaw, and Microsoft has known about it for years. The company has also updated Windows versions to stop "corp" from being the default. But there are clearly still many companies using it. And even though Microsoft has now sheltered their data, it's still a good idea to use a domain they can control.