Earlier this week, Mark Zuckerberg's Twitter and Pinterest accounts were hacked with a person familiar with the matter claiming he reused the password: "dadada". One of Facebook's primary security tips is not to reuse the same passwords anywhere else online. The Facebook boss was quite fortunate however, with "OurMine Team" who hacked his Pinterest saying they were just testing Zuckerberg's security.The infographic below shows a list of the 10 most popular LinkedIn passwords which were revealed during a 2012 hack when the details of 117 million users were stolen. "123456" was the most popular password by far, used by over 750,000 accounts according to LeakedSource . The second most popular was "linkedin" (172,000 accounts) followed by "password" (144,000 accounts).