Hacker News Reader

From the Article "I've not heard of an attack of this nature and scale on a UK bank where it appears that the bank's central system is the target"

Sounds like it's a breach from within (or at least not though compromised accounts), this would explain the lack of concern from Tesco about resting security (much to the chagrin of customers, i'm sure) and the huge numbers of affected accounts.

there was a victim on the radio this morning saying his account had been breached. But he said the account is one he just uses for savings. He received the card in the post years ago and it has sat in his safe ever since. It's never left his house. So couldn't understand how someone could have ever got his details

Sounds like the bank got breached, not the customer.

Disclaimer: I don't use Tesco Bank so this is just speculation and some observations.

The types of 2FA vary dramatically between banks. Some use an SMS OTP but as we know phone numbers aren't secure [0]. Most use a card reader but they often do this differently. Some use the 'identify' function to log on and the 'sign' function for payments (as designed) but others use the 'respond' function for everything. The danger in using 'respond' for payments is that the account and amount aren't entered into the card reader so you don't know what you are authorising.

<pure-speculation>

If Tesco have a flaw in how they are using 2FA, by only using 'respond', then local malware could intercept genuine payments, alter the account/amount details, and get the user to authorise this. Or Android malware could intercept SMS messages. N.B. This assumes the issue is in the faster payments system but it could be in the payment card system. It appears cash points still work but this is a separate system to debit card payments.

</pure-speculation>

From what I've read no one will lose money but having transactions frozen is still a big inconvenience. As mentioned elsewhere here, this is why it's a good idea to have many different bank accounts from various parent institutions (also important from a deposit guarantee position). Some banks share the same infrastructure and liability. Always have some cash available too, although that is getting harder to spend everywhere [1].

[0]: https://unop.uk/phone-numbers-for-examples-and-user-identifi...

[1]: https://unop.uk/do-you-accept-cash/

Welp, just because you get to have Verizon give up your phone number because someone asked nicely doesn't mean it is universally a bad idea

Hell, I can't even get authenticated with my provider half the time because the simcard comes with it's ID/PIN/password that is printed on your contract. You need that to do any changes on your account.

I personally think cell phones can be made secure enough and are the most convenient. If somebody really wants to fuck with you, they will anyway, for most people there is not much point to it anyway

Not all banking systems require 2FA, phone banking doesn't.

If tested systems that allow you to transfer money between accounts, if you can bypass the initial authentication you can transfer money without needing to use 2FA or generating a TUN code.

And these systems can be breached.

Well there hasn't been an APT (Advanced Persistent Threat) attack yet on a UK bank yet (although we've seen them on banks in the developing world). Perhaps this is the first and perhaps the attackers figures that doing many smaller transactions would work for longer than big ones.

could be entirely a software bug? Though I tend to agree that it looks worse than that.

Sure. All it takes is a REST endpoint without the proper XSRF checks.

This was my first thought. A lot of the replies here are going all out, but it is likely some simple web vuln that trusts the browser.

    /transfer_money?from_account=NNNN&to_account=MMMM&amount=$$$$

It would actually be really interesting if they faxed in transfer forms or something.

That hasn't been released, but I think it's interesting that the original press releases frames this as a matter of fraud rather than a breach.

I personally doubt this will be revealed to be a software security issue.

Agreed with your concerns. The fact that it was widespread and no action from Tesco that indicates any understanding of what was compromised suggests they have no clue.

So they may still be vulnerable. If UK customers can find a low (or no) cost alternative place to put what remains of their money, I'd do that now. This might not be over.

They may not know how the attackers gained access or if they're still inside until incident responders have done a full workup on the network.

i believe tesco is a customer services front end to hsbc, so i doubt that its a bank end/ accounting problem. since its only online payments that have been stopped it suggests a card details leak, including the security code. i imagine this would only affect cards that dont have the 2 factor (mastercard/visa) step set up. perhaps a successful phishing or malware attack which has targeted tesco users

No, Tesco Bank is wholly owned by Tesco; you're thinking of M&S Bank, which is a front end to HSBC.

i can say for sure the few times ive had issues transferring money overseas tesco customer services claim to be checking the status on an hsbc system

Maybe their forex is via Hsbc?

I think you might mean SWIFT (wordlwide) or SEPA (euro area + other EU).

Forex typically means buying or selling currencies, not transferring money between parties.

It's a moot point, but forex's are also used to move money internationally. It is ultimately buying and selling currencies, but you get much better rates than through the bank because the forex isn't actually moving your money. It's receiving money into accounts which are in the senders country, and then, using its accounts in the receivers country, it pays the receiver.

Also means the receiver doesn't get hit with fees to receive an international payment.

Some of the smaller banks and building societies seem to use larger banks like HSBC to process transfers.

That still seems odd... phishing & malware attacks are going on all the time, so a targetted strike on Tesco bank users all at the same time would be a very 'restrained' attack. Phishing would take place over several days, so the attackers would be gathering account details piece by piece. Also, the first thing that banks tend to do when a large scale phishing attack has been successful is to re-issue new passwords and card numbers, yet Tesco haven't done this. So whatever avenue of attack the hackers had, Tesco must be confident that they have closed it off without needing to junk any compromised account details?

Not on RBS platform anymore, they moved their current accounts off that to fiserv:

http://www.computerweekly.com/news/2240222351/Tesco-Bank-lau...

I interpreted "online payments" to mean payments to accounts via online banking, rather than credit/debit card payments online.

If it was a card details leak, I'd have expected cards to be cancelled, and not allowing them to continue to be used.

definitely making card payments online is currently blocked. a text message ive received says SO and debit orders will continue as normal

There are stories of people losing 2000 pounds leaving them with only 20 pounds left in the account. Hard to believe such people could get credit cards with a 2k limit. Also if the fraudulent payments were card payments why not just reverse them in the normal way. It sounds more like bank wires.

> Hard to believe such people could get credit cards with a 2k limit

Unfortunately that's totally plausible, and infact, are the profitable customers for credit card companies. Why give a credit card to someone who can pay off their bills in full every month, when you can give someone more credit than they earn, let them spend it all, and then pay you monthly with interest?

As a point of reference, my Amex limit is 5x my monthly post-tax earnings. Back when I was only eligible for entry cards, at £250 limit increased to >£5k within a year.

It does sound like bank transfers - either SWIFT or Faster Payments. If it's a backend attack they could well have bypassed all the usual checks, including checking for positive balance & overdraft limits.