Four years later, Yahoo still doesn’t know how 3 billion accounts were hacked

In a security hearing that called both Equifax and Yahoo’s past and present executives to Washington, D.C., we’re learning a bit more about what Yahoo didn’t know about the biggest hack in history. When pressed about how Yahoo failed to recognize that 3 billion accounts were compromised, former Yahoo CEO Marissa Mayer admitted that the specifics of the attack still remain unknown.