Category Archives: Banking security

The security of the banking system, as well as hardware and software commonly used in such installations

Banks biased against black fraud victims

The following is an op-ed I wrote in today’s Times. It appeared in their Thunderer column.

You’re less likely to be treated fairly by your bank if you’re elderly, poor, female or black. We’ve suspected this for years, and finally The Times has dug up the numbers to prove it.

Fraud victims who’re refused compensation often contact our security research group at Cambridge after they find we work on payment fraud. We call this stream of complaints our ‘fraud telescope’ as it gives us early warning of what the bad guys are up to. We’ve had more than 2,000 cases over 25 years.

In recent years we’ve started to realise what we weren’t seeing. The “dark matter” in the fraud universe is the missing victims: we don’t see that many middle-class white men. The victims who do come to us are disproportionately elderly, poor, female, or black. But crime surveys tell us that the middle classes and the young are more likely to be victims of fraud, so it’s hard to avoid the conclusion that banks are less generous to some of their customers.

We raised the issue of discrimination in 2011 with one of the banks and with the Commission for Racial Equality, but as no-one was keeping records, nothing could be proved, until today.

How can this discrimination happen? Well, UK rules give banks a lot of discretion to decide whether to refund a victim, and the first responders often don’t know the full story. If your HSBC card was compromised by a skimmer on a Tesco ATM, there’s no guarantee that Tesco will have told anyone (unlike in America, where the law forces Tesco to tell you). And the fraud pattern might be something entirely new. So bank staff end up making judgement calls like “Is this customer telling the truth?” and “How much is their business worth to us?” This in turn sets the stage for biases and prejudices to kick in, however subconsciously. Add management pressure to cut costs, sometimes even bonuses for cutting them, and here we are.

There are two lessons. First, banks need to train staff to be aware of unconscious bias (as universities do), and monitor their performance.

Second, the Financial Conduct Authority needs to protect all customers properly. It seems to be moving in the right direction; after the recent fraud against tens of thousands of Tesco Bank account holders, it said it expected fraud victims to be made good immediately. This has been the law in the USA since the 1980s and it must become a firm rule here too.


Last week I gave a keynote talk at CCS about DigiTally, a project we’ve been working on to extend mobile payments to areas where the network is intermittent, congested or non-existent.

The Bill and Melinda Gates Foundation called for ways to increase the use of mobile payments, which have been transformative in many less developed countries. We did some research and found that network availability and cost were the two main problems. So how could we do phone payments where there’s no network, with a marginal cost of zero? If people had smartphones you could use some combination of NFC, bluetooth and local wifi, but most of the rural poor in Africa and Asia use simple phones without any extra communications modalities, other than those which the users themselves can provide. So how could you enable people to do phone payments by simple user actions? We were inspired by the prepayment electricity meters I helped develop some twenty years ago; meters conforming to this spec are now used in over 100 countries.

We got a small grant from the Gates Foundation to do a prototype and field trial. We designed a system, Digitally, where Alice can pay Bob by exchanging eight-digit MACs that are generated, and verified, by the SIM cards in their phones. For rapid prototyping we used overlay SIMs (which are already being used in a different phone payment system in Africa). The cryptography is described in a paper we gave at the Security Protocols Workshop this spring.

Last month we took the prototype to Strathmore University in Nairobi to do a field trial involving usability studies in their bookshop, coffee shop and cafeteria. The results were very encouraging and I described them in my talk at CCS (slides). There will be a paper on this study in due course. We’re now looking for partners to do deployment at scale, whether in phone payments or in other apps that need to support value transfer in delay-tolerant networks.

There has been press coverage in the New Scientist, Engadget and Impress (original Japanese version).

Yet another Android side channel: input stealing for fun and profit

At PETS 2016 we presented a new side-channel attack in our paper Don’t Interrupt Me While I Type: Inferring Text Entered Through Gesture Typing on Android Keyboards. This was part of Laurent Simon‘s thesis, and won him the runner-up to the best student paper award.

We found that software on your smartphone can infer words you type in other apps by monitoring the aggregate number of context switches and the number of hardware interrupts. These are readable by permissionless apps within the virtual procfs filesystem (mounted under /proc). Three previous research groups had found that other files under procfs support side channels. But the files they used contained information about individual apps– e.g. the file /proc/uid_stat/victimapp/tcp_snd contains the number of bytes sent by “victimapp”. These files are no longer readable in the latest Android version.

We found that the “global” files – those that contain aggregate information about the system – also leak. So a curious app can monitor these global files as a user types on the phone and try to work out the words. We looked at smartphone keyboards that support “gesture typing”: a novel input mechanism democratized by SwiftKey, whereby a user drags their finger from letter to letter to enter words.

This work shows once again how difficult it is to prevent side channels: they come up in all sorts of interesting and unexpected ways. Fortunately, we think there is an easy fix: Google should simply disable access to all procfs files, rather than just the files that leak information about individual apps. Meanwhile, if you’re developing apps for privacy or anonymity, you should be aware that these risks exist.

GCHQ helps banks dump fraud losses on customers

We recently reported that the Commissioner of the Met, Sir Bernard Hogan-Howe, said that banks should not refund fraud victims as this would just make people careless with their passwords and antivirus. The banks’ desire to blame fraud victims if they can, to avoid refunding them, is rational enough, but for a police chief to support them was disgraceful. Thirty years ago, a chief constable might have said that rape victims had themselves to blame for wearing nice clothes; if he were to say that nowadays, he’d be sacked. Hogan-Howe’s view of bank fraud is just as uninformed, and just as offensive to victims.

Our spooky friends at Cheltenham have joined the party. The Register reports a story in the Financial Times (behind a paywall) which says GCHQ believes that “companies must do more to try and encourage their customers to improve their cyber security standards. Customers using outdated software – sometimes riddled with vulnerabilities that hackers can exploit – are a weak link in the UK’s cyber defences.” There is no mention of the banks’ own outdated technology, or of GCHQ’s role in keeping consumer software vulnerable.

The elegant scribblers at the Financial Times are under the impression that “At present, banks routinely cover the cost of fraud, regardless of blame.” So they clearly are not regular readers of Light Blue Touchpaper.

The spooks are slightly more cautious; according to the FT, GCHQ “has told the private sector it will not take responsibility for regulatory failings”. I’m sure the banks will heave a big sigh of relief that their cosy relationship with the police, the ombudsman and the FCA will not be disturbed.

We will have to change our security-economics teaching material so we don’t just talk about the case where “Alice guards a system and Bob pays the costs of failure”, but also this new case where “Alice guards a system, and bribes the government to compel Bob to pay the costs of failure.” Now we know how Hogan-Howe is paid off; the banks pay for his Dedicated Card and Payment Crime Unit. But how are they paying off GCHQ, and what else are they getting as part of the deal?

Security Protocols 2016

I’m at the 24th security protocols workshop in Brno (no, not Borneo, as a friend misheard it, but in the Czech republic; a two-hour flight rather than a twenty-hour one). We ended up being bumped to an old chapel in the Mendel museum, a former monastery where the monk Gregor Mendel figured out genetics from the study of peas, and for the prosaic reason that the Canadian ambassador pre-empted our meeting room. As a result we had no wifi and I have had to liveblog from the pub, where we are having lunch. The session liveblogs will be in followups to this post, in the usual style.

Met police chief blaming the victims

Commissioner Hogan-Howe of the Met said on Thursday that the banks should not refund fraud victims because it “rewards” them for being lax about internet security. This was too much to pass up, so I wrote a letter to the editor of the Times, which has just been published. As the Times is behind a paywall, here is the text.

Sir, Sir Bernard Hogan-Howe argues that banks should not refund online fraud victims as this would make people careless with their passwords and anti-virus software (p1, March 24, and letters Mar 25 & 26). This is called secondary victimisation. Thirty years ago, a chief constable might have said that rape victims had themselves to blame for wearing nice clothes; if he were to say that nowadays, he’d be sacked. Hogan-Howe’s view of bank fraud is just as uninformed, and just as offensive to victims.

About 5 percent of computers running Windows are infected with malware, and common bank fraud malware such as Zeus lets the fraudster redirect transactions. You think you’re paying £150 to your electricity bill, while the malware is actually sending £9000 to Russia. The average person is helpless against this; everything seems normal, and antivirus products usually only detect it afterwards.

Much of the blame lies with the banks, who let the users of potentially infected computers make large payments instantly, rather than after a day or two, as used to be the case. They take this risk because regulators let them dump much of the cost of the resulting fraud on customers.

The elephant in the room is that the Met has been claiming for years that property crime is falling, when in fact it’s just going online like everything else. We’re now starting to get better crime figures; it’s time we got better policing, and better bank regulation too.

Ross Anderson FRS FREng
Professor of Security Engineering
University of Cambridge

Financial Cryptography 2016

I will be trying to liveblog Financial Cryptography 2016, which is the twentieth anniversary of the conference. The opening keynote was by David Chaum, who invented digital cash over thirty years ago. From then until the first FC people believed that cryptography could enable commerce and also protect privacy; since then pessimism has slowly set in, and sometimes it seems that although we’re still fighting tactical battles, we’ve lost the war. Since Snowden people have little faith in online privacy, and now we see Tim Cook in a position to decide which seventy phones to open. Is there a way to fight back against a global adversary whose policy is “full take”, and where traffic data can be taken with no legal restraint whatsoever? That is now the threat model for designers of anonymity systems. He argues that in addition to a large anonymity set, a future social media system will need a fixed set of servers in order to keep end-to-end latency within what chat users expect. As with DNS we should have servers operated by (say ten) different principals; unlike in that case we don’t want to have most of the independent parties financed by the US government. The root servers could be implemented as unattended seismic observatories, as reported by Simmons in the arms control context; such devices are fairly easy to tamper-proof.

The crypto problem is how to do multi-jurisdiction message processing that protects not just content but also metadata. Systems like Tor cost latency, while multi-party computation costs a lot of cycles. His new design, PrivaTegrity, takes low-latency crypto building blocks then layers on top of them transaction protocols with large anonymity sets. The key component is c-Mix, whose spec up as an eprint here. There’s a precomputation using homomorphic encryption to set up paths and keys; in real-time operations each participating phone has a shared secret with each mix server so things can run at chat speed. A PrivaTegrity message is four c-Mix batches that use the same permutation. Message models supported include not just chat but publishing short anonymous messages, providing an untraceable return address so people can contact you anonymously, group chat, and limiting sybils by preventing more than one pseudonym being used. (There are enduring pseudonyms with valuable credentials.) It can handle large payloads using private information retrieval, and also do pseudonymous digital transactions with a latency of two seconds rather than the hour or so that bitcoin takes. The anonymous payment system has the property that the payer has proof of what he paid to whom, while the recipient has no proof of who paid him; that’s exactly what corrupt officials, money launderers and the like don’t want, but exactly what we do want from the viewpoint of consumer protection. He sees PrivaTegrity as the foundation of a “polyculture” of secure computing from multiple vendors that could be outside the control of governments once more. In questions, Adi Shamir questioned whether such an ecosystem was consistent with the reality of pervasive software vulnerabilities, regardless of the strength of the cryptography.

I will try to liveblog later sessions as followups to this post.

The emotional cost of cybercrime

We know more and more about the financial cost of cybercrime, but there has been very little work on its emotional cost. David Modic and I decided to investigate. We wanted to empirically test whether there are emotional repercussions to becoming a victim of fraud (Yes, there are). We wanted to compare emotional and financial impact across different categories of fraud and establish a ranking list (And we did). An interesting, although not surprising, finding was that in every tested category the victim’s perception of emotional impact outweighed the reported financial loss.

A victim may think that they will still be able to recover their money, if not their pride. That really depends on what type of fraud they facilitated. If it is auction fraud, then their chances of recovery are comparatively higher than in bank fraud – we found that 26% of our sample would attempt to recover funds lost in a fraudulent auction and approximately half of them were reimbursed (look at this presentation). There is considerable evidence that banks are not very likely to believe someone claiming to be a victim of, say, identity theft and by extension bank fraud. Thus, when someone ends up out of pocket, they will likely also go through a process of secondary victimisation where they will be told they broke some small-print rule like having the same pin for two of their bank cards or not using the bank’s approved anti-virus software, and are thus not eligible for any refund and it is all their own fault, really.

You can find the article here or here. (It was published in IEEE Security & Privacy.)

This paper complements and extends our earlier work on the costs of cybercrime, where we show that the broader economic costs to society of cybercrime – such as loss of confidence in online shopping and banking – also greatly exceed the amounts that cybercriminals actually manage to steal.