Email or username:

Password:

Forgot your password?
Top-level
Bjorn Toft Madsen

I was informed that there had been a charge for £2900 on a travel booking site.

As this conversation with my bank’s counter-fraud team was happening, I logged into my bank account and could see the fraudulent charge.

“Was this you?”

No, it definitely wasn’t me. Phew, well done for catching it.

“Also, sir, there is another transaction occurring right now that seems odd - for £5900 at Marbella Boat Hire. Is this you?”

11 comments
Bjorn Toft Madsen

Nope, that wasn’t me either.

At this point, my pulse was obviously raised and I was worried what else was going on.

“Ok, sir, we are going to send you a verification code, which we need you to read back to cancel the transaction”.

Ok, bit odd, but yeah, let’s go and get these cancelled.

Bjorn Toft Madsen

Then a text/SMS message arrives with a six digit code. I put the call on speaker so I can read it out.

And I notice something odd…

Bjorn Toft Madsen

The full text of the message says: “Do not share this message with anyone. To approve the purchase from Marbella Boat Hire for £5900, use code 638267”.

Hold on, I say, this says “to approve the purchase”!

“Ah, right, sir, we’ve had a few problems with our messaging system, so I’m not 100% sure what the message actually says. We just need the code so we can get the purchase blocked. You can ignore the start of the message”.

My spider-sense is tingling, so I challenge…

Bjorn Toft Madsen

I can’t share this code, I say.

“No, sir, that’s very smart. I’m so sorry about our messaging system being odd. Let me send you a notification inside your banking app instead”.

The notification arrives and I open my banking app, thinking a hitherto red warning label is about to show me a button to cancel a transaction inside the app.

But again it just says “to approve this transaction”.

Now I’m starting to worry …

Bjorn Toft Madsen

So finally I say, look, I need to call my bank directly. This all seems a bit odd.

And then, naturally (in retrospect), the guy hangs up.

I call my bank. They verify that it wasn’t them.

Bjorn Toft Madsen

So, very cleverly, the fraudster has used their first fraudulent transaction to socially verify that they knew something only a bank could know - about transactions on my card.

They used that transaction - that they themselves had done - to get me to read a 3D secure code to approve the next transaction that they also wanted to do.

Bjorn Toft Madsen

They were able to to do this because the first transaction had happened on a site that didn’t use 3D secure. I’m surprised this is still possible.

In the end, my bank refunded the first transaction. So I haven’t lost anything.

But it shows the clever tricks fraudsters will try to pull and how easy it is to be fooled by the “boiler room” trick. “IT’S HAPPENING RIGHT NOW - DO SOMETHING QUICK!”

End 🧵

Terence Eden

@BjornToftMadsen that's fascinating. And easy to see why people would fall for that.
I wonder where they got your card details *and* phone number from?

Robin Whittleton

@BjornToftMadsen when I’ve had calls from my bank I always ask for a name, then tell them I’m going to ring them back from the support number on their website. General confusion from the bank, but so far it’s worked every time. Luckily I’ve not yet had a fraudulent call.

Neil Henning

@BjornToftMadsen wow man! Good on you for spotting the con though.

Go Up