Education

Can Games Fix What’s Wrong with Computer Security Education?

We had the pleasure of Zachary Peterson visiting UCL on a Cyber Security Fulbright Scholarship. The title is from his presentation given at our annual ACE-CSR event in November 2016.

Zachary Peterson is an associate professor of computer science at Cal Poly, San Luis Obispo. The key problem he is trying to solve is that the educational system is producing many fewer computer security professionals than are needed; an article he’d seen just two days before the ACE meeting noted a 73% rise in job vacancies in the last year despite a salary premium of 9% over other IT jobs. This information is backed up by the 2014 Taulbee survey, which found that the number of computer security PhDs has declined to 4% of the US total. Lack of diversity, which sees security dominated by white and Asian males, is a key contributing factor. Peterson believes that diversity is not only important as a matter of fairness, but essential because white males are increasingly a demographic minority in the US and because monocultures create perceptual blindness. New perspectives are especially needed in computer security as present approaches are not solving the problem on their own.

Peterson believes that the numbers are so bad because security is under-represented in both the computer science curriculum and in curriculum standards. The ACM 2013 curriculum guidelines recommend only three contact hours (also known as credit hours) in computer security in an entire undergraduate computer science degree. These are typically relegated to an upper-level elective class, and subject to a long chain of prerequisites, so they are only ever seen by a self-selected group who have survived years of attrition – which disproportionately affects women. The result is to create a limited number of specialists, unnecessarily constrain the student body, and limit the time students have to practice before joining the workforce. In addition, the self-selected group who do study security late in their academic careers have developed both set habits and their mind set before encountering an engineering task. Changing security into a core competency and teaching it as early as secondary school is essential but has challenges: security can be hard, and pushing it to the forefront may worsen existing problems seen in computer science more broadly, such as the solitary, anti-social, creativity-deficient image perception of the discipline.

Peterson believes games can help improve this situation. CTFTime, which tracks games events, reports a recent explosion in cyber security games to over 56 games events per year since 2013. These games, if done correctly, can teach core security skills in an entertaining – and social – way, with an element of competition. Strategic thinking, understanding an adversary’s motivation, rule interpretation, and rule-breaking are essential for both game-playing and security engineering.

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Security intrusions as mechanisms

The practice of security often revolves around figuring out what (malicious act) happened to a system. This historical inquiry is the focus of forensics, specifically when the inquiry regards a policy violation (such as a law). The results of forensic investigation might be used to fix the impacted system, attribute the attack to adversaries, or build more resilient systems going forwards. However, to execute any of these purposes, the investigator first must discover the mechanism of the intrusion.

As discussed at an ACE seminar last October, one common framework for this discovery task is the intrusion kill chain. Mechanisms, mechanistic explanation, and mechanism discovery have highly-developed meanings in the biological and social sciences, but the word is not often used in information security. In a recent paper, we argue that incident response and forensics investigators would be well-served to make use of the existing literature on mechanisms, as thinking about intrusion kill chains as mechanisms is a productive and useful way to frame the work.

To some extent, thinking mechanistically is a description of what (certain) scientists do. But the mechanisms literature within philosophy of science is not merely descriptive. The normative benefits extolled include that thinking mechanistically is an effective heuristic for searching out useful explanations; mechanisms provide the most coherent unity to complex fields of study; and that mechanistic explanation is necessary to guide selection among potential studies given limited experimental resources, experiment design decisions, and interpretation of statistical results. I previously argued that capricious use of biological metaphors is bad for information security. We are keenly aware that these benefits of mechanistic explanation need to apply to security as and for security, not merely because they work in other sciences.

Our paper demonstrates how we can cast the intrusion kill chain, the diamond model, and other models of security intrusions as mechanistic models. This casting begins to demonstrate the mosaic unity of information security. Campaigns are made up of attacks. Attacks, as modeled by the kill chain, have multiple steps. In a specific attack, the delivery step might be accomplished by a drive-by-download. So we demonstrate how drive-by-downloads are a mechanism, one among many possible delivery mechanisms. This description is a schema to be filled in during a particular drive-by download incident with a specific URL and specific javascript, etc. The mechanistic schema of the delivery mechanism informs the investigator because it indicates what types of network addresses to look for, and how to fit them into the explanation quickly. This process is what Lindley Darden calls schema instantiation in the mechanism discovery literature.

Our argument is not that good forensics investigators do not do such mechanism discovery strategies. Rather, it is precisely that good investigators do do them. But we need to describe what it is good investigators in fact do. We do not currently, and that lack makes teaching new investigators particularly difficult. Thinking about intrusions as mechanisms unlocks an expansive literature on good ways to do mechanism discovery. This literature will make it easier to codify what good investigators do, which among other benefits allows us to better teach sound methodological practices to incoming investigators.

Our paper on this topic was published in the open-access Journal of Cybersecurity, as Thinking about intrusion kill chains as mechanisms, by Jonathan M. Spring and Eric Hatleback.

Steven Murdoch – Privacy and Financial Security

Probably not too many academic researchers can say this: some of Steven Murdoch’s research leads have arrived in unmarked envelopes. Murdoch, who has moved to UCL from the University of Cambridge, works primarily in the areas of privacy and financial security, including a rare specialty you might call “crypto for the masses”. It’s the financial security aspect that produces the plain, brown envelopes and also what may be his most satisfying work, “Trying to help individuals when they’re having trouble with huge organisations”.

Murdoch’s work has a twist: “Usability is a security requirement,” he says. As a result, besides writing research papers and appearing as an expert witness, his past includes a successful start-up. Cronto, which developed a usable authentication device, was acquired by VASCO, a market leader in authentication and is now used by banks such as Commerzbank and Rabobank.

Developing the Cronto product was, he says, an iterative process that relied on real-world testing: “In research into privacy, if you build unusable system two things will go wrong,” he says. “One, people won’t use it, so there’s a smaller crowd to hide in.” This issue affects anonymising technologies such as Mixmaster and Mixminion. “In theory they have better security than Tor but no one is using them.” And two, he says, “People make mistakes.” A non-expert user of PGP, for example, can’t always accurately identify which parts of the message are signed and which aren’t.

The start-up experience taught Murdoch how difficult it is to get an idea from research prototype to product, not least because what works in a small case study may not when deployed at scale. “Selling privacy remains difficult,” he says, noting that Cronto had an easier time than some of its forerunners since the business model called for sales to large institutions. The biggest challenge, he says, was not consumer acceptance but making a convincing case that the predicted threats would materialise and that a small company could deliver an acceptable solution.

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User-centred security awareness empowers employees to be the strongest defense

The release of our business whitepaper “Awareness is only the first step” was recently announced by Hewlett Packard Enterprise (HPE). The whitepaper is co-authored by HPE, UCL, and the UK government’s National Technical Authority for Information Assurance (CESG). The whitepaper emphasises how a user-centred approach to security awareness can empower employees to be the strongest link in defending their organisation. As Andrzej Kawalec, HPE’s Security Services CTO, notes in the press release:

“Users remain the first line of defense when faced with a dynamic and relentless threat environment.”

Security communication, education, and training (CET) in organisations is intended to align employee behaviour with the security goals of the organisation. Security managers conduct regular security awareness activities – familiar vehicles for awareness programmes, such as computer-based training (CBT), can cover topics such as password use, social media practices, and phishing. However, there is limited evidence to support the effectiveness or efficiency of CBT, and a lack of reliable indicators means that it is not clear if recommended security behaviour is followed in practice. If the design and delivery of CET programmes does not consider the individual, they can’t be certain of achieving the intended outcomes. As Angela Sasse comments:

“Many companies think that setting up web-based training packages are a cost-effective way of influencing staff behavior and achieving compliance, but research has provided clear evidence that this is not effective – rather, many staff resent it and suffer from ‘compliance fatigue.’”

HPE awareness maturity curve

The whitepaper describes a path to guide the involvement of employees in their own security, as shown in the HPE awareness maturity curve above. To change security behaviors, a company needs to invest in the security knowledge and skills of its employees, and respond to employee needs differently at each stage.

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First UCL team competes in the International Capture The Flag competition

Team THOR, UCL’s Capture the Flag (CTF) team, took part in its first CTF competition – the UCSB iCTF, on the 4th December 2015. The team comprised of students from the computer science department – Tom Sigler, Chris Park, Jason Papapanagiotakis, Azeem Ilyas, Salman Khalifa, Luke Roberts, Haran Anand, Alexis Enston, Austin Chamberlain, Jaromir Latal, Enrico Mariconti, and Razvan Ragazan. Through Gianluca Stringhini’s hacking seminars and our own experience, we were eager to test our ability to identify, exploit and patch application vulnerabilities.

The THOR team in action

The CTF competition style was “attack and defence” with a slight twist – each participating team had to write a vulnerable application. We were provided with a Linux virtual machine containing all of the applications which we hosted on a locally running server. This server connected to the organiser’s network over a virtual private network (VPN). During the competition, the organiser regularly polled our server to make sure each of the applications were running and whether or not they still had a security vulnerability. We were scored on 3 criteria: how many applications were up and running (and whether or not the vulnerabilities had been patched), how many flags we had managed to obtain through exploiting vulnerabilities and how close our submitted application was to the median in terms of being vulnerable, but not too vulnerable.

The application had to be “balanced” in terms of security i.e. if it was too easy or too difficult to exploit then points would be deducted. Fortunately, the organisers provided sample applications which gave us an excellent starting point. One of the sample applications was a “notes” service written in PHP – it enabled a note (which represented the flag) to be saved against a flag ID with a password. The note could be retrieved by supplying the flag ID and password, but a vulnerable CGI script enabled the note to be retrieved without a password! We customised this application by removing the CGI script (this vulnerability was very easy to identify and exploit) and changing the note insertion code so that a specially crafted token (a hex-encoded Epoch timestamp) was added next to each flag ID, password and note entry. A vulnerability was then introduced whereby note retrieval would be a two-step process – first the flag ID and password would be specified, then if the password was valid, the token would be retrieved and used in combination with the flag ID to retrieve the note. The first step of the process could be bypassed by brute-forcing the token and avoiding the password verification phase. We kept our fingers crossed that this would be exploitable by the other teams, but not too easily!

Attacking involved analysing the various applications written by the other teams for vulnerabilities. As soon as a vulnerability had been identified, we had to write some code to perform the exploit and retrieve the flag for that application. The flag served as evidence that we had successfully exploited an application. To maximise attack points, we had to run the exploit against each team’s server and submit the flags to the organiser every few minutes. Defence involved ensuring that the applications were up and running, keeping the server online and ideally patching any vulnerabilities identified in our copies of the applications.

The competition started at 5pm – we were online with our server and applications shortly afterwards. Fueled by adrenaline, caffeine, and immense enthusiasm, we chose several applications to focus our initial efforts on and got cracking!

A good portion of the applications were web applications written in PHP. This was great news as we had focused on web application vulnerabilities during the hacking seminars. We also identified applications written in Python, Java, C and Bash. Some of them were imaginative and amusing – a dating service for monkeys written in PHP, a pizza order and delivery service written in PHP and a command-line dungeon game written in C.

We managed to exploit and patch an ATM machine application through a SQL injection vulnerability (the same security vulnerability involved in the recent TalkTalk and vTech data breaches). One of the Python applications used a “pickle” function which was exploited to enable arbitrary code execution. A second Python application was vulnerable to a path-traversal bug which enabled flags to be retrieved from other user’s directories. We also were on the cusp of exploiting a buffer-overflow vulnerability in a C application, but ran out of time.

The competition ran for 8 hours and at the end, THOR ranked 14th out of 35. Given that it was THOR’s first time participating in a CTF, being the only team to represent the UK and being up against experienced teams, we felt that it was a great result! We had a huge amount of fun taking part and working as a team, so much so, that we are planning to take part in more CTF competitions in the future! Many thanks again to Gianluca, the organisers and all who participated. Go THOR!

Nicolas Courtois – Algebraic cryptanalysis is not the best way to break something, but sometimes it is the only option

Nicolas Courtois, a mathematician and senior lecturer in computer science at UCL, working with Daniel Hulme and Theodosis Mourouzis, has won the 2012 best paper award from the International Academy, Research, and Industry Association for their work on using SAT solvers to study various problems in algebra and circuit optimization. The research was funded by the European Commission under the FP7 project number 242497, “Resilient Infrastructure and Building Security (RIBS)” and by the UK Technology Strategy Board under project 9626-58525. The paper, Multiplicative Complexity and Solving Generalized Brent Equations with SAT Solvers, was presented at Computation Tools 2012, the third International Conference on Computational Logics, Algebras, Programming, Tools, and Benchmarking, held in Nice, France in July.

https://www.youtube.com/watch?v=Lfen7ZOIkYw

SAT (short for “satisfiability”) solvers are algorithms used to analyse logical problems composed of multiple statements such as “A is true OR not-B is true or C is true” for the purpose of determining whether the whole system can be true – that is, whether all the statements it’s composed of can be satisfied. SAT solvers also are used to determine how to assign the variables to make the set of statements true. In 2007, Bard and Courtois realised they could be used to test the security of cryptographic functions and measure their complexity, and today they are important tools in cryptanalysis; they have already been used for a long time in other applications such as verifying hardware and software. In this particular paper, Courtois, Hulme, and Mourouzis focused on optimising S-boxes for industrial block ciphers; the paper reports the results of applying their methodology to the PRESENT and GOST block ciphers. Reducing the complexity and hardware cost of these ciphers is particularly important to build so-called secure implementations of cryptography. These are particularly costly because they need to protect against additional threats such as side-channel attacks, in which the attacker exploits additional information leaked from the physical system – for example, by using an oscilloscope to observe a smart card’s behaviour.

“It’s more a discovery than an invention,” says Courtois. “One of the amazing things SAT solvers can do is give you proof that something is not true.” The semiconductor industry provides one application of the work in this paper: these techniques promise to provide a way to test whether a circuit has been built with the greatest possible efficiency by proving that the chip design uses the smallest possible number of logic gates.

“You’ll get optimal designs and be able to prove they cannot be done better,” he says.

Classical cryptanalysis proceeds by finding approximations to the way a cipher works. Many successful academic attacks have been mounted using such techniques, but they rely on having a relatively large amount of data available for study. That works for large archives of stored data – such as, for example, the communications stored and kept by the Allies after World War II for later cryptanalysis. But in many real-world applications, it is more common to have only very small amounts of data.

“The more realistic scenario is that you’ll just have one or a few messages,” says Courtois. Bluetooth, for example, encrypts only 1,500 bits with a single key. “Most attacks are useless because they won’t work with this quantity of data.” Algebraic cryptanalysis, which he explained in New Frontier in Symmetric Cryptanalysis, an invited talk at Indocrypt 2008, by contrast, is one of the few techniques that can be hoped to work in such difficult situations.

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New EU Innovative Training Network project “Privacy & Us”

Last week, “Privacy & Us” — an Innovative Training Network (ITN) project funded by the EU’s Marie Skłodowska-Curie actions — held its kick-off meeting in Munich. Hosted in the nice and modern Wisschenschafts Zentrum campus by Uniscon, one of the project partners, principal investigators from seven different countries set out the plan for the next 48 months.

Privacy & Us really stands for “Privacy and Usability” and aims to conduct privacy research and, over the next 3 years, train thirteen Early Stage Researchers (ESRs) — i.e., PhD students — to be able to reason, design, and develop innovative solutions to privacy research challenges, not only from a technical point of view but also from the “human side”.

The project involves nine “beneficiaries”: Karlstads Universitet (Sweden), Goethe Universitaet Frankfurt (Germany), Tel Aviv University (Israel), Unabhängiges Landeszentrum für Datenschutz (Germany), Uniscon (Germany), University College London (UK), USECON (Austria), VASCO Innovation Center (UK), and Wirtschaft Universitat Wien (Austria), as well as seven partner organizations: the Austrian Data Protection Authority (Austria), Preslmayr Rechtsanwälte OG (Austria), Friedrich-Alexander University Erlangen (Germany), University of Bonn (Germany), the Bavarian Data Protection Authority (Germany), EveryWare Technologies (Italy), and Sentor MSS AB (Sweden).

The people behind Privacy & Us project at the kick-off meeting in Munich, December 2015

The Innovative Training Networks are interdisciplinary and multidisciplinary in nature and promote, by design, a collaborative approach to research training. Funding is extremely competitive, with acceptance rate as low as 6%, and quite generous for the ESRs who often enjoy higher than usual salaries (exact numbers depend on the hosting country), plus 600 EUR/month mobility allowance and 500 EUR/month family allowance.

The students will start in August 2016 and will be trained to face both current and future challenges in the area of privacy and usability, spending a minimum of six months in secondment to another partner organization, and participating in several training and development activities.

Three studentships will be hosted at UCL, under the supervision of Dr Emiliano De Cristofaro, Prof. Angela Sasse, Prof. Ann Blandford, and Dr Steven Murdoch. Specifically, one project will investigate how to securely and efficiently store genomic data, design and implementing privacy-preserving genomic testing, as well as support user-centered design of secure personal genomic applications. The second project will aim to better understand and support individuals’ decision-making around healthcare data disclosure, weighing up personal and societal costs and benefits of disclosure, and the third (with the VASCO Innovation Centre) will explore techniques for privacy-preserving authentication, namely, extending these to develop and evaluate innovative solutions for secure and usable authentication that respects user privacy.

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Scaling Tor hidden services

Tor hidden services offer several security advantages over normal websites:

both the client requesting the webpage and the server returning it can be anonymous;
websites’ domain names (.onion addresses) are linked to their public key so are hard to impersonate; and
there is mandatory encryption from the client to the server.

However, Tor hidden services as originally implemented did not take full advantage of parallel processing, whether from a single multi-core computer or from load-balancing over multiple computers. Therefore once a single hidden service has hit the limit of vertical scaling (getting faster CPUs) there is not the option of horizontal scaling (adding more CPUs and more computers). There are also bottle-necks in the Tor networks, such as the 3–10 introduction points that help to negotiate the connection between the hidden service and the rendezvous point that actually carries the traffic.

For my MSc Information Security project at UCL, supervised by Steven Murdoch with the assistance of Alec Muffett and other Security Infrastructure engineers at Facebook in London, I explored possible techniques for improving the horizontal scalability of Tor hidden services. More precisely, I was looking at possible load balancing techniques to offer better performance and resiliency against hardware/network failures. The focus of the research was aimed at popular non-anonymous hidden services, where the anonymity of the service provider was not required; an example of this could be Facebook’s .onion address.

One approach I explored was to simply run multiple hidden service instances using the same private key (and hence the same .onion address). Each hidden service periodically uploads its own descriptor, which describes the available introduction points, to six hidden service directories on a distributed hash table. The hidden service instance chosen by the client depends on which hidden service instance most recently uploaded its descriptor. In theory this approach allows an arbitrary number of hidden service instances, where each periodically uploads its own descriptors, overwriting those of others.

This approach can work for popular hidden services because, with the large number of clients, some will be using the descriptor most recently uploaded, while others will have cached older versions and continue to use them. However my experiments showed that the distribution of the clients over the hidden service instances set up in this way is highly non-uniform.

I therefore ran experiments on a private Tor network using the Shadow network simulator running multiple hidden service instances, and measuring the load distribution over time. The experiments were devised such that the instances uploaded their descriptors simultaneously, which resulted in different hidden service directories receiving different descriptors. As a result, clients connecting to a hidden service would be balanced more uniformly over the available instances.

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George Danezis – Smart grid privacy, peer-to-peer and social network security

“I work on technical aspects of privacy,” says George Danezis, a reader in security and privacy engineering at UCL and part of the Academic Centre of Excellence in Cyber Security Research (ACE-CSR). There are, of course, many other limitations: regulatory, policy, economic. But, he says, “Technology is the enabler for everything else – though you need everything else for it to be useful.” Danezis believes providing privacy at the technology level is particularly important as it seems clear that both regulation and the “moralising” approach (telling people the things they shouldn’t do) have failed.

https://www.youtube.com/watch?v=wAbKB0kaH6c

There are many reasons why someone gets interested in researching technical solutions to intractable problems. Sometimes the motivation is to eliminate a personal frustration; other times it’s simply a fascination with the technology itself. For Danezis, it began with other people.

“I discovered that a lot of the people around me could not use technology out of the box to do things personally or collectively.” For example, he saw NGOs defending human rights worry about sending an email or chatting online, particularly in countries hostile to their work. A second motivation had to do with timing: when he began work it wasn’t yet clear that the Internet would develop into a medium anyone could use freely to publish stories. That particular fear has abated, but other issues such as the need for anonymous communications and private data sharing are still with us.

“Without anonymity we can’t offer strong privacy,” he says.

Unlike many researchers, Danezis did not really grow up with computers. He spent his childhood in Greece and Belgium, and until he got Internet access at 16, “I had access only to the programming books I could find in an average Belgian bookshop. There wasn’t a BBC Micro in every school and it was difficult to find information. I had one teacher who taught me how to program in Logo, and no way of finding more information easily.” Then he arrived at Cambridge in 1997, and “discovered thousands of people who knew how to do crazy stuff with computers.”

Danezis’ key research question is, “What functionality can we achieve while still attaining a degree of hard privacy?” And the corollary: at what cost in complexity of engineering? “We can’t just say, let’s recreate the whole computer environment,” he said. “We need to evolve efficiently out of today’s situation.”

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Gianluca Stringhini – Cyber criminal operations and developing systems to defend against them

Gianluca Stringhini’s research focuses on studying cyber criminal operations and developing systems to defend against them.

Such operations tend to follow a common pattern. First the criminal operator lures a user into going to a Web site and tries to infect them with malware. Once infected, the user is joined to a botnet. From there, the user’s computer is instructed to perform malicious activities on the criminal’s behalf. Stringhini, whose UCL appointment is shared between the Department of Computer Science and the Department of Security and Crime Science, has studied all three of these stages.

https://www.youtube.com/watch?v=TY3wsqGOZ28

Stringhini, who is from Genoa, developed his interest in computer security at college: “I was doing the things that all college students are doing, hacking, and breaking into systems. I was always interested in understanding how computers work and how one could break them. I started playing in hacking competitions.”

At the beginning, these competitions were just for fun, but those efforts became more serious when he arrived in 2008 at UC Santa Barbara, which featured one of the world’s best hacking teams, a perennial top finisher in Defcon’s Capture the Flag competition. It was at Santa Barbara that his interest in cyber crime developed, particularly in botnets and the complexity and skill of the operations that created them. He picked the US after Christopher Kruegel, whom he knew by email, invited him to Santa Barbara for an internship. He liked it, so he stayed and did a PhD studying the way criminals use online services such as social networks

“Basically, the idea is that if you have an account that’s used by a cyber criminal it will be used differently than one used by a real person because they will have a different goal,” he says. “And so you can develop systems that learn about these differences and detect accounts that are misused.” Even if the attacker tries to make their behaviour closely resemble the user’s own, ultimately spreading malicious content isn’t something normal users intend to do, and the difference is detectable.

This idea and Stringhini’s resulting PhD research led to his most significant papers to date.

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