Category Archives: Banking security

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

Video on Edge

John Brockman of Edge interviewed me in London in March. The video of the interview, and a transcript, are now available on the Edge website. Edge runs big interviews with several dozen scientists a year, with particular interest in people who do cross-disciplinary work. For me, the interaction of economics, psychology and engineering is one of the things that makes security so fascinating, as well as the creativity driven by adversarial behaviour.

The topics covered include the last thirty years of progress (of lack of it) in information security, from the early beginnings, through the crypto wars and crime moving online, to the economics of security. We talked about how cryptography can help less developed countries; about managing complexity in big projects; about how network effects lead firms to design insecure products; about whether big data can undermine democracy by empowering elites; and about how in a future world of intelligent things, security may become more about safety than anything else. Finally I talk about our current big project, the Cambridge Cybercrime Centre.

John runs a literary agency, and he’s worked on books by many of the scientists who feature on his site. This makes me wonder: on what topic should I write my next book?

Configuring Zeus

We presented “Configuring Zeus: A case study of online crime target selection and knowledge transmission” at APWG’s eCrime 2017 conference this past week in Scottsdale Arizona. The paper is here, and the slides from Richard Clayton’s talk are here.

Zeus (sometimes called Zbot) is a family of credential stealing malware which was widely deployed from 2007 to 2012 or so. It belongs to a class of malware dubbed ‘man-in-the-browser‘ (a play on a ‘man in the middle attack’) in that it runs on end-user machines where it can intercept web browser traffic to extract login credentials or to manipulate the page content displayed to the user.

It has been used to attack large numbers of sites, mainly banks — its extreme flexibility is achieved with ‘configuration files’ that indicate which websites are to be targeted, which user submitted fields are to be collected, what webpage rewriting (so called ‘webinjects’) is required and where the results are to be sent.

The complexity of these files seem to have restricted the number of websites actually targeted. In a paper presented at WEIS 2014 Tajalizadehkhoob et al. examined a large number of configuration files and described this lack of development and measured a substantial overlap in the content of different files. As a result, the authors suggested that offenders were not developing configuration files from scratch but were selling, sharing or stealing them.

We decided to test out this conjecture by seeking out messages about Zeus configuration files on underground forums (many of these are have been scraped, leaked or confiscated by law enforcement) — and this paper describes how we found evidence to support all three mechanisms: selling, sharing and stealing.

The paper also gives an account of the history of Zeus with illustrations from the messages that were uncovered along with clear evidence the release of tools to decrypt configuration files by security researchers was also closely followed on the forums, and assisted offenders when it came to stealing configuration files from others.

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.

DigiTally

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