The latest hack on Facebook that allowed outside parties the ability to control about 50 million people's accounts was "a sophisticated attack," according to Carolyn Everson, Facebook's vice president of global marketing solutions.

"This was an attack, an attack that would require people to understand three different bugs," Everson said at an Advertising Week panel on Monday.

Everson compared the attackers to an "odorless, weightless intruder that walked in" that Facebook could only detect "once they made a certain move."

Facebook announced on Sept. 28 it had discovered attackers had taken advantage of vulnerabilities in its "View As" feature, which would let them have control of about 50 million accounts. The investigation is in its early stages, and the FBI and other authorities have been notified. The accounts in question and a precautionary 40 million other users had their automatic login reset as a precaution. No password or credit card information was taken.

Comparing the recent incident to the Cambridge Analytica data breach, Everson said both were Facebook's responsibility. However, while she admitted Facebook was to blame for not re-checking with Cambridge Analytica to make sure the company deleted the improperly accessed data, she said the discovery of the recent hack is a sign Facebook is becoming more proactive at finding issues on its platform.

"This is the most significant cultural shift: Recognizing our responsibility, taking very specific actions and doing everything we can," she said.

Everson also addressed WhatsApp co-founder Brian Acton's critical remarks about Facebook, saying she'd like to "hear more about their philanthropy" stemming from the $19 billion deal WhatsApp received when Facebook acquired the messaging app.

She also talked about the recent departure of Instagram co-founders Kevin Systrom and Mike Krieger, which she called a "very, very friendly and cordial departure."

"Those of us that have worked with them, we all were surprised they even stayed six years," she said. "Most entrepreneurs leave after a year or two. ... It's a testament to Mark [Zuckerberg] giving entrepreneurs autonomy."