It harvested personal information via Facebook with one of those personality test apps you see in various forms all over the internet.
Only five per cent of people can pass this intelligence test. Which 80s pop group are you?
Social media is awash with them.
Only this one was more sophisticated and sinister.
What's especially galling about Cambridge Analytica was they not only convinced 270,000 people to sign away their rights and do the stupidity test, they were then able to exploit Facebook's data sharing rules to access the friends of those people.
That netted the data of 50 million unsuspecting people.
Don't do those tests and quizzes, people!
But even if you are you are using Facebook cautiously you are vulnerable to the actions of some distant contact that you only friended to be polite.
Thankfully, the revelations in US and UK media have sparked a backlash.
Whether it really changes anything in the long run remains to be seen.
It's easy to look at your Facebook feed and wonder what the issue is. What sort of data do I have that is worth mining?
Kids' birthday parties, camping holidays, a bit of a rant about the local bus service. If you're smart you don't share the serious stuff, right?
Well, many people do. And they have a right to do that and should have a right to choose with whom they share that.
Yes, we sign away rights in the terms and conditions but there's an assumption of responsible, ethical sharing implicit in the agreement.
It's one Facebook promoted from its inception and it's a trust Facebook has belatedly admitted to betraying.
Bear in mind Cambridge Analytica wasn't using the data it harvested to blackmail those with unpalatable political views.
It was looking for people whose unpalatable views made them potential Trump voters. That enabled Trump's campaign to direct-market to them mobilise the vote in key battleground States.
It worked.
The idea privacy doesn't really matter assumes we live in a world of benign corporate and governmental forces.
I actually believe that, by and large, we do, in New Zealand at least. And for now.
But look around the world or back through history. There are no guarantees.
Plenty of Americans are currently questioning that proposition.
There is the issue of choice, of course. You didn't have to sign up to Facebook. You can delete your profile.
Sure, we don't have to use social media any more than citizens of East Germany didn't have to use telephones they knew were probably bugged.
But seriously, what a drag.
New technology offers us extensions to human behaviour.
If we can't trust it – and it looks like we can't – we lose the freedom to openly express ourselves. Our social media selves become a pale shadow of real human personalities.
That's where the comparisons to Orwell start to ring true.
If we integrate fully with a technology that creates limits rather than freedoms how is that progress?
It is certainly not what we were sold.
If there's any good news here it's Facebook has been punished by investors. It tried to portray itself as a victim. No one is buying it.
Its shares dropped in value about US$50b last week. That's something Mark Zuckerberg the board and management will pay attention to.
Zuckerberg apologised and promised to make changes.
He is also likely to face a Congressional hearing and scrutiny from the US privacy regulator.
It would be great to see regulators tighten privacy rules to protect social media users but one suspects the genie is out of the bottle.
For better or worse we now live in a world where we have to moderate what we say and share in the knowledge we are being watched – even if those watching are, for now, relatively benign.
I doubt anything will get me off Facebook any time soon.
It has become too deeply embedded in my life. I like seeing what old friends are up to.
And although I find the idea of outsourcing my memories to a tech company disturbing, its ability to store photos and anniversaries and share them with me unprompted is pretty handy.
But I know those friends won't be seeing the real me and it's likely I'm not seeing the real them.
This week's revelations are a reminder that although social media can be a useful tool we mustn't let it crowd out our real life.
