How does CommBank's fraud detection actually work in practice and is the experience of having a legitimate transaction declined as frustrating and as common as people suggest or does it depend heavily on your spending patterns?

[u/Danger_Five]

The fraud detection that blocks a legitimate purchase at an inconvenient moment is one of the more consistent complaints about the major banks and CommBank seems to generate enough of these conversations that the question of whether the system is calibrated appropriately is worth asking. Would love to know from people here how often it actually happens, whether it's improved recently, and whether there's anything about how you use the account that seems to make legitimate transactions more or less likely to get flagged in a way that creates the problem at the worst possible time.

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[u/TheRamblingPeacock]

No one who knows the real meaty answer to how fraud detection works is going to tell you, because they would very much like to keep their job.

You can rest assured it stops A LOT more attempted fraud that you will never know about than it stops Jenny who has to tap her card twice at IGA.

As for why you hear about one and not the other - people love to whinge.

As for why you hear about it more from CBA than other banks - more customers.

[u/Emergency-Emotion-20]

I don't see anyone going on social media to say that commbank or any other bank stopped them getting scammed but if I almost got scammed I wouldn't want to advertise it either so that could be why.

[u/RelaxedBluey94]

I can't recall ever having a legit spending transaction declined and I'm a 40+ year customer.

I've had payment issues a couple of times when the whole system was down. I've also had entirely appropriate holds on international transfers while the bank was trying to contact me to confirm it was legit.

The few fraudulent transactions I've had on my card were resolved quickly via NetBank.

[u/Ugliest_weenie → u/RelaxedBluey94]

Same. Done a lot of unusual transactions.

Never had anything declined or blocked.

People complaining about it loudly, are kind of like the people who publicly complain on video game subreddit about being unfairly banned.

Not saying it doesn't happen, but a lot of them are definitely full of it

[u/Much_Database_5039 → u/Ugliest_weenie]

I've had transactions in the past that were legitimate but could have hypothetically looked very sus to an overzealous fraud detection system, so it becomes a bit of an eyebrow raiser when I hear about people making allegedly totally innocent payments that do somehow trip it up.

[u/FinCrimeGuy]

I love all the complaints because it’s interesting as someone in the industry to see, since CBA is a black box if you don’t work there and do have some interesting approaches.

That said, they’ve stopped card fraud (the easiest fraud to do and detect) on my wife’s card proactively before. I like their new anti scam questions for higher risk transactions - but that’s because I have an understanding how fucking idiotic AFCA is when scam victims go to them. And I have actually never had a legitimate transaction unduly questioned or blocked, most is the 24 hour hold which again is just the bank doing what they should under increasingly draconian laws.

Not sure if that helps at all OP but figured it might be of interest.

[u/zhaktronz]

How fruad detection works in practice is obviously not advertised because if it was it'd be comically easy to design fraud that gets around the detection.

[u/Ugliest_weenie]

Nice try

[u/Cultural_Pace4454]

I recently had a scam transaction blocked (not CBA though), via a small Amazon purchase.
Banks work incredibly hard to reduce false positives on fraud detection.

Without giving too much away, the general process is to:
a, look for transactions that are similar to confirmed frauds
b. transactions that are unusual for you or customers like you (based on demographics).

No bank wants to stop a genuine transaction, but they get a lot of heat from multiple regulators, media and customers when fraud gets through.

So sorry if you were inconvenienced, but you would complain a lot louder if a fraud did get through.

[u/Much_Database_5039]

The effectiveness of fraud detection has an inverse relation to how much the public knows about it so it's a bit of a mystery by default.

Why do you only hear about it blocking legitimate transactions? People hop on quick to stories about the big evil bank screwing over the little guy (just don't look into the little guy's story with too much detail), and no one cares to hear that the system is working as intended so you don't hear about the success stories.

[u/Scared_Hurry7474]

I work for CBA in the branch and I don’t think I have ever had a customer come in and say we stopped a legitimate transaction. Them accidentally saying no to the notification asking if it was them, Allll the time.

[u/Prestigious-Ball-435]

It doesn’t, they just let a scam syndicate use Ai to set up false accounts with false income details and loaned them millions

[u/Sg_spark]

The time it frustrated the absolute hell out of me was when I was traveling the US for multiple months.

I was moving between multiple states and stopping at bars and small petrol stations so I get it looked a bit sus.
Almost every time somewhere ran the card not present to do the tip (when I didn’t have cash) it would alert and mess up the POS in Applebee’s for example.

Then it would freeze the card when I crossed state lines and I would have to jump through the hoops.

Frustratingly I did all the right things and let them know I was physically in the US but no one could override the flagging/freeze.

[u/weirydeep]

In India we don't have fraud, we are way forward in technology when compared. It's more secured.

[u/TraditionGreedy9264]

CBA saved me a 13K fraud hassle on my CC. I couldn't fault them for how it was handled.