This year, hacking group OurMine has successfully broke into accounts of major public figures — including Mark Zuckerberg, Sundar Pichai and Jack Dorsey — who ironically are the world’s top tech executives (and Katy Perry).

Although these attacks pose a threat to personal information and data, most of these incidents have been harmless and, in fact, funny. On its website, the hacking collective OurMine states: “We have no bad intentions and only care about the security and privacy of your accounts and networks.” So far, this statement stands true, as the group positions itself as a security company offering services to help rather than harm online privacy.

For the majority of these high-profile hacks, the group posts variations of “we are just testing your security” and tagging themselves.

Regardless of their intentions — good or bad — the number of hack attacks is always growing and poses privacy concerns for not only celebrities but anyone who has ever created a social media account (Facebook, Twitter, Myspace — you name it).

From Zuckerberg to Google’s Pichai, the list goes on. Check out some big names who got their handles hacked.

Mark Zuckerberg

Facebook advises its users to never reuse a password on multiple accounts, The Wall Street Journal points out. Had its CEO and founder took this advice more seriously, he could have prevented his Twitter and Pinterest accounts from being hacked this past June. Zuckerberg’s not-so-difficult-to-guess password “dadada” — which was originally leaked in 2012 when 100 million LinkedIn passwords were stolen — proved not so strong against hackers.

 Sundar Pichai

Shortly after Zuckerberg’s hack, OurMine sought its next victim, Google CEO Sundar Pichai, whose Quora account was unlocked, also granting the hackers the ability to post to his Twitter. Releasing their tactic to the tech website The Next Web, an OurMine insider said the team found an “exploit” in Quora that granted them access to Pichai’s account. In response to the hack, Quora denied any vulnerabilities in its system.

 Dick Costolo

Even former Twitter CEO Dick Costolo fell victim to OurMine attacks, according to Recode. The hackers logged into an old account that enabled them to cross post onto his Twitter, again claiming only to be testing for “security” purposes.

Jack Dorsey

 Now that’s ironic. On top of the former Twitter CEO’s hack, current Twitter CEO and co-founder Jack Dorsey’s account was recently hacked as well.

Similar to Kalanick’s hack, without gaining direct access to his Twitter, the hackers cross-posted tweets through a different social avenue, this time through video platform Vine (owned by Twitter). Along with tweeting their typical “testing your security” post, hackers also posted a number of Vine videos which have since been deleted, reports Engadget.

Marissa Mayer

Marissa Mayer joins the list of tech CEOs hacked. After attacking Dorsey, the hacking group made its way into the Yahoo! CEO’s account. Similar to what we’ve seen in previous attacks, OurMine cross-posted onto Mayer’s Twitter through another social channel — although it is unknown which.

Brendan Iribe

Oculus CEO Brendan Iribe’s hack was a rare case — it wasn’t an attack from OurMine but rather an independent hacker, “Lid,” according to TechCrunch.

Although a harmless attack, the hacker admits in a post on Iribe’s account “i’m not testin ya security im just havin a laugh.” And a laugh it was — the hacker took to the CEO’s Twitter to announce himself as Oculus’ new CEO.

This year, OurMine has also tapped into accounts of Uber CEO Travis Kalanick, Amazon CTO Werner Vogels, Spotify founder Daniel Ek, former America Online CEO and co-founder Steve Case, and, oh yeah, Channing Tatum.