The company has been on the defensive after reports that political data firm Cambridge Analytica obtained personal data from as many as 87 million Facebook users without their permission. The scandal has led to broader questions about how Facebook and other social media networks manage data, and Facebook has been changing its privacy policies and tools in response.

"What we didn't do until recently and what we are doing now is just take a broader view looking to be more restrictive in ways data could be misused. We also didn't build our operations fast enough -- and that's on me," she added.

"I feel deeply personally responsible, because a lot of mistakes were made," Sandberg said in an interview with Bloomberg.

Facebook COO Sheryl Sandberg echoed CEO Mark Zuckerberg's rhetoric on Thursday, by taking personal responsibility for letting third parties access Facebook user data without permission.

In an interview with press on Wednesday, Zuckerberg said he expects most of Facebook's users who had a specific search function enabled had their public data scraped by a third party.

"It is reasonable to expect... someone has accessed your information in this way," he said.

Sandberg addressed that comment as well, emphasizing that "all of that was public information." She also went into greater detail on how Facebook has begun and will continue to address its privacy issues.

Beginning Monday, Facebook will roll out tools to allow users to view which apps they've connected to an how to delete them. Facebook also intends to inform users if they have been impacted by the Cambridge Analytica leak. And by the end of the year, they will have doubled the amount of staffers they have dedicated to security. The company also plans to "invest massively" into smart technology to this effect.

Sandberg, like Zuckerberg in his chat with press on Wednesday, emphasized that data management and security improvements will likely take several years.

"This is a forever process, because security is always an arms race," Sandberg said during an interview with Bloomberg.

And Sandberg readily acknowledged such a huge effort would require a huge investment.

"We've never run this company for short term gains, we've run this for long-term health of our business. These investments are big and they will impact profitability and that's OK with us, because its the right thing to do," she said.

Sandberg said the company will likely dig into more specific estimates of how that might impact profitability in the next quarter.

When asked about Zuckerberg's fitness to lead, she fully backed him up.

"I believe deeply in Mark," she said.

Zuckerberg will testify before Congress next week on the social media site's privacy policies.