Entries Tagged "academic papers"

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Online Credit/Debit Card Security Failure

Ross Anderson reports:

Online transactions with credit cards or debit cards are increasingly verified using the 3D Secure system, which is branded as “Verified by VISA” and “MasterCard SecureCode”. This is now the most widely-used single sign-on scheme ever, with over 200 million cardholders registered. It’s getting hard to shop online without being forced to use it.

In a paper I’m presenting today at Financial Cryptography, Steven Murdoch and I analyse 3D Secure. From the engineering point of view, it does just about everything wrong, and it’s becoming a fat target for phishing. So why did it succeed in the marketplace?

Quite simply, it has strong incentives for adoption. Merchants who use it push liability for fraud back to banks, who in turn push it on to cardholders. Properly designed single sign-on systems, like OpenID and InfoCard, can’t offer anything like this. So this is yet another case where security economics trumps security engineering, but in a predatory way that leaves cardholders less secure. We conclude with a suggestion on what bank regulators might do to fix the problem.

Posted on February 1, 2010 at 6:26 AM • View Comments

The Power Law of Terrorism

Research result #1: “A Generalized Fission-Fusion Model for the Frequency of Severe Terrorist Attacks,” by Aaron Clauset and Frederik W. Wiegel.

Plot the number of people killed in terrorists attacks around the world since 1968 against the frequency with which such attacks occur and you’ll get a power law distribution, that’s a fancy way of saying a straight line when both axis have logarithmic scales.

The question, of course, is why? Why not a normal distribution, in which there would be many orders of magnitude fewer extreme events?

Aaron Clauset and Frederik Wiegel have built a model that might explain why. The model makes five simple assumptions about the way terrorist groups grow and fall apart and how often they carry out major attacks. And here’s the strange thing: this model almost exactly reproduces the distribution of terrorists attacks we see in the real world.

These assumptions are things like: terrorist groups grow by accretion (absorbing other groups) and fall apart by disintegrating into individuals. They must also be able to recruit from a more or less unlimited supply of willing terrorists within the population.

Research Result #2: “Universal Patterns Underlying Ongoing Wars and Terrorism,” by Neil F. Johnson, Mike Spagat, Jorge A. Restrepo, Oscar Becerra, Juan Camilo Bohorquez, Nicolas Suarez, Elvira Maria Restrepo, and Roberto Zarama.

In the case of the Iraq war, we might ask how many conflicts causing ten casualties are expected to occur over a one-year period. According to the data, the answer is the average number of events per year times 10­-2.3, or 0.005. If we instead ask how many events will cause twenty casualties, the answer is proportional to 20­-2.3. Taking into account the entire history of any given war, one finds that the frequency of events on all scales can be predicted by exactly the same exponent.

Professor Neil Johnson of Oxford University has come up with a remarkable result regarding these power laws: for several different wars, the exponent has about the same value. Johnson studied the long-standing conflict in Colombia, the war in Iraq, the global rate of terrorist attacks in non-G7 countries, and the war in Afghanistan. In each case, the power law exponent that predicted the distribution of conflicts was close to the value ­2.5.

This doesn’t surprise me; power laws are common in naturally random phenomena.

Posted on January 12, 2010 at 1:46 PM • View Comments

768-bit Number Factored

News:

On December 12, 2009, we factored the 768-bit, 232-digit number RSA-768 by the number field sieve. The number RSA-768 was taken from the now obsolete RSA Challenge list as a representative 768-bit RSA modulus. This result is a record for factoring general integers. Factoring a 1024-bit RSA modulus would be about a thousand times harder, and a 768-bit RSA modulus is several thousands times harder to factor than a 512-bit one. Because the first factorization of a 512-bit RSA modulus was reported only a decade ago it is not unreasonable to expect that 1024-bit RSA moduli can be factored well within the next decade by an academic effort such as ours…. Thus, it would be prudent to phase out usage of 1024-bit RSA within the next three to four years.

[…]

Our computation required more than 1020 operations. With the equivalent of almost 2000 years of computing on a single core 2.2GHz AMD Opteron, on the order of 267 instructions were carried out. The overall effort is sufficiently low that even for short-term protection of data of little value, 768-bit RSA moduli can no longer be recommended.

News articles.

Posted on January 11, 2010 at 8:00 AM • View Comments

The Psychology of Being Scammed

This is a very interesting paper: “Understanding scam victims: seven principles for systems security,” by Frank Stajano and Paul Wilson. Paul Wilson produces and stars in the British television show The Real Hustle, which does hidden camera demonstrations of con games. (There’s no DVD of the show available, but there are bits of it on YouTube.) Frank Stajano is at the Computer Laboratory of the University of Cambridge.

The paper describes a dozen different con scenarios—entertaining in itself—and then lists and explains six general psychological principles that con artists use:

1. The distraction principle. While you are distracted by what retains your interest, hustlers can do anything to you and you won’t notice.

2. The social compliance principle. Society trains people not to question authority. Hustlers exploit this “suspension of suspiciousness” to make you do what they want.

3. The herd principle. Even suspicious marks will let their guard down when everyone next to them appears to share the same risks. Safety in numbers? Not if they’re all conspiring against you.

4. The dishonesty principle. Anything illegal you do will be used against you by the fraudster, making it harder for you to seek help once you realize you’ve been had.

5. The deception principle. Things and people are not what they seem. Hustlers know how to manipulate you to make you believe that they are.

6. The need and greed principle. Your needs and desires make you vulnerable. Once hustlers know what you really want, they can easily manipulate you.

It all makes for very good reading.

Two previous posts on the psychology of conning and being conned.

EDITED TO ADD (12/12): Some of the episodes of The Real Hustle are available on the BBC site, but only to people with UK IP addresses—or people with a VPN tunnel to the UK.

Posted on November 30, 2009 at 6:17 AM • View Comments

Users Rationally Rejecting Security Advice

This paper, by Cormac Herley at Microsoft Research, sounds like me:

Abstract: It is often suggested that users are hopelessly lazy and
unmotivated on security questions. They chose weak passwords, ignore security warnings, and are oblivious to certicates errors. We argue that users’ rejection of the security advice they receive is entirely rational from an economic perspective. The advice offers to shield them from the direct costs of attacks, but burdens them with far greater indirect costs in the form of effort. Looking at various examples of security advice we find that the advice is complex and growing, but the benefit is largely speculative or moot. For example, much of the advice concerning passwords is outdated and does little to address actual threats, and fully 100% of certificate error warnings appear to be false positives. Further, if users spent even a minute a day reading URLs to avoid phishing, the cost (in terms of user time) would be two orders of magnitude greater than all phishing losses. Thus we find that most security advice simply offers a poor cost-benefit tradeoff to users and is rejected. Security advice is a daily burden, applied to the whole population, while an upper bound on the benefit is the harm suffered by the fraction that become victims annually. When that fraction is small, designing security advice that is beneficial is very hard. For example, it makes little sense to burden all users with a daily task to spare 0.01% of them a modest annual pain.

Sounds like me.

EDITED TO ADD (12/12): Related article on usable security.

Posted on November 24, 2009 at 12:40 PM • View Comments

Denial-of-Service Attack Against CALEA

Interesting:

The researchers say they’ve found a vulnerability in U.S. law enforcement wiretaps, if only theoretical, that would allow a surveillance target to thwart the authorities by launching what amounts to a denial-of-service (DoS) attack against the connection between the phone company switches and law enforcement.

[…]

The University of Pennsylvania researchers found the flaw after examining the telecommunication industry standard ANSI Standard J-STD-025, which addresses the transmission of wiretapped data from telecom switches to authorities, according to IDG News Service. Under the 1994 Communications Assistance for Law Enforcement Act, or Calea, telecoms are required to design their network architecture to make it easy for authorities to tap calls transmitted over digitally switched phone networks.

But the researchers, who describe their findings in a paper, found that the standard allows for very little bandwidth for the transmission of data about phone calls, which can be overwhelmed in a DoS attack. When a wiretap is enabled, the phone company’s switch establishes a 64-Kbps Call Data Channel to send data about the call to law enforcement. That paltry channel can be flooded if a target of the wiretap sends dozens of simultaneous SMS messages or makes numerous VOIP phone calls “without significant degradation of service to the targets’ actual traffic.”

As a result, the researchers say, law enforcement could lose records of whom a target called and when. The attack could also prevent the content of calls from being accurately monitored or recorded.

The paper. Comments by Matt Blaze, one of the paper’s authors.

Posted on November 20, 2009 at 6:11 AM • View Comments

Stabbing People with Stuff You Can Get Through Airport Security

“Use of a pig model to demonstrate vulnerability of major neck vessels to inflicted trauma from common household items,” from the American Journal of Forensic Medical Pathology.

Abstract. Commonly available items including a ball point pen, a plastic knife, a broken wine bottle, and a broken wine glass were used to inflict stab and incised wounds to the necks of 3 previously euthanized Large White pigs. With relative ease, these items could be inserted into the necks of the pigs next to the jugular veins and carotid arteries. Despite precautions against the carrying of metal objects such as knives and nail files on board domestic and international flights, objects are still available within aircraft cabins that could be used to inflict serious and potentially life-threatening injuries. If airport and aircraft security measures are to be consistently applied, then consideration should be given to removing items such as glass bottles and glass drinking vessels. However, given the results of a relatively uncomplicated modification of a plastic knife, it may not be possible to remove all dangerous objects from aircraft. Security systems may therefore need to focus on measures such as increased surveillance of passenger behavior, rather than on attempting to eliminate every object that may serve as a potential weapon.

Posted on November 19, 2009 at 7:10 AM • View Comments

How Smart are Islamic Terrorists?

Organizational Learning and Islamic Militancy (May 2009) was written by Michael Kenney for the U.S. Department of Justice. It’s long: 146 pages. From the executive summary:

Organizational Learning and Islamic Militancy contains significant findings for counter-terrorism research and policy. Unlike existing studies, this report suggests that the relevant distinction in knowledge learned by terrorists is not between tacit and explicit knowledge, but metis and techne. Focusing on the latter sheds new insight into how terrorists acquire the experiential “know how” they need to perform their activities as opposed to abstract “know what” contained in technical bomb-making preparations. Drawing on interviews with bomb-making experts and government intelligence officials, the PI illustrates the critical difference between learning terrorism skills such as bomb-making and weapons firing by abstraction rather than by doing. Only the latter provides militants with the experiential, intuitive knowledge, in other words the metis, they need to actually build bombs, fire weapons, survey potential targets, and perform other terrorism-related activities. In making this case, the PI debunks current misconceptions regarding the Internet’s perceived role as a source of terrorism knowledge.

Another major research finding of this study is that while some Islamic militants learn, they do not learn particularly well. Much terrorism learning involves fairly routine adaptations in communications practices and targeting tactics, what organization theorists call single-loop learning or adaptation. Less common among militants are consequential changes in beliefs and values that underlie collection action or even changes in organizational goals and strategies. Even when it comes to single-loop learning, Islamic militants face significant impediments. Many terrorist conspiracies are compartmented, which makes learning difficult by impeding the free flow of information between different parts of the enterprise. Other, non-compartmented conspiracies are hindered from learning because the same people that survey targets and build bombs also carry out the attacks. Still other operations, including relatively successful ones like the Madrid bombings in 2004, are characterized by such sloppy tradecraft that investigators piece together the conspiracy quickly, preventing additional attacks and limiting militants’ ability to learn from experience.

Indeed, one of the most significant findings to emerge from this research regards the poor tradecraft and operational mistakes repeatedly committed by Islamic terrorists. Even the most “successful” operations in recent years—9/11, 3/11, and 7/7—contained basic errors in tradecraft and execution. The perpetrators that carried out these attacks were determined, adaptable (if only in a limited, tactical sense)—and surprisingly careless. The PI extracts insights from his informants that help account for terrorists’ poor tradecraft: metis in guerrilla warfare that does not translate well to urban terrorism, the difficulty of acquiring mission-critical experience when the attack or counter-terrorism response kills the perpetrators, a hostile counter-terrorism environment that makes it hard to plan and coordinate attacks or develop adequate training facilities, and perpetrators’ conviction that they don’t need to be too careful when carrying out attacks because their fate has been predetermined by Allah. The PI concludes this report by discussing some of the policy implications of these findings, suggesting that the real threat from Islamic militancy comes less from hyper-sophisticated “super terrorists” than from steadfast militants whose own dedication to the cause may undermine the cunning intelligence and fluid adaptability they need to survive.

Posted on November 18, 2009 at 1:45 PM • View Comments

Quantum Ghost Imaging

This is cool:

Ghost imaging is a technique that allows a high-resolution camera to produce an image of an object that the camera itself cannot see. It uses two sensors: one that looks at a light source and another that looks at the object. These sensors point in different directions. For example, the camera can face the sun and the light meter can face an object.

That object might be a soldier, a tank or an airplane, Ron Meyers, a laboratory quantum physicist explained during an Oct. 28 interview on the Pentagon Channel podcast “Armed with Science: Research and Applications for the Modern Military.”

Once this is done, a computer program compares and combines the patterns received from the object and the light. This creates a “ghost image,” a black-and-white or color picture of the object being photographed. The earliest ghost images were silhouettes, but current ones depict the objects more realistically.

[…]

Using virtually any light source—from a fluorescent bulb, lasers, or even the sun—quantum ghost imaging gives a clearer picture of objects by eliminating conditions such as clouds, fog and smoke beyond the ability of conventional imaging.

EDITED TO ADD (12/12): A better explanation of the effect, and a detailed paper.

Posted on November 18, 2009 at 6:22 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.