Entries Tagged "academic papers"

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Cost-Benefit Analysis of Full-Body Scanners

Research paper from Mark Stewart and John Mueller:

The Transportation Security Administration (TSA) has been deploying Advanced Imaging Technologies (AIT) that are full-body scanners to inspect a passenger’s body for concealed weapons, explosives, and other prohibited items. The terrorist threat that AITs are primarily dedicated to is preventing the downing of a commercial airliner by an IED (Improvised Explosive Device) smuggled on board by a passenger. The cost of this technology will reach $1.2 billion per year by 2014. The paper develops a cost-benefit analysis of AITs for passenger screening at U.S. airports. The analysis considered threat probability, risk reduction, losses, and costs of security measures in the estimation of costs and benefits. Since there is uncertainty and variability of these parameters, three alternate probability (uncertainty) models were used to characterise risk reduction and losses. Economic losses were assumed to vary from $2-50 billion, and risk reduction from 5-10%. Monte-Carlo simulation methods were used to propagate these uncertainties in the calculation of benefits, and the minimum attack probability necessary for AITs to be cost-effective was calculated. It was found that, based on mean results, more than one attack every two years would need to originate from U.S. airports for AITs to pass a cost-benefit analysis. In other words, to be cost-effective, AITs every two years would have to disrupt more than one attack effort with body-borne explosives that otherwise would have been successful despite other security measures, terrorist incompetence and amateurishness, and the technical difficulties in setting off a bomb sufficiently destructive to down an airliner. The attack probability needs to exceed 160-330% per year to be 90% certain that AITs are cost-effective.

EDITED TO ADD (1/26): Response from one of the paper’s authors.

Posted on January 20, 2011 at 1:39 PM • View Comments

Hiding PETN from Full-Body Scanners

From the Journal of Transporation Security, “An evaluation of airport x-ray backscatter units based on image characteristics,” by Leon Kaufman and Joseph W. Carlson:

Abstract:

Little information exists on the performance of x-ray backscatter machines now being deployed through UK, US and other airports. We implement a Monte Carlo simulation using as input what is known about the x-ray spectra used for imaging, device specifications and available images to estimate penetration and exposure to the body from the x-ray beam, and sensitivity to dangerous contraband materials. We show that the body is exposed throughout to the incident x-rays, and that although images can be made at the exposure levels claimed (under 100 nanoGrey per view), detection of contraband can be foiled in these systems. Because front and back views are obtained, low Z materials can only be reliable detected if they are packed outside the sides of the body or with hard edges, while high Z materials are well seen when placed in front or back of the body, but not to the sides. Even if exposure were to be increased significantly, normal anatomy would make a dangerous amount of plastic explosive with tapered edges difficult if not impossible to detect.

From the paper:

It is very likely that a large (15-20 cm in diameter), irregularly-shaped, cm-thick pancake with beveled edges, taped to the abdomen, would be invisible to this technology, ironically, because of its large volume, since it is easily confused with normal anatomy. Thus, a third of a kilo of PETN, easily picked up in a competent pat down, would be missed by backscatter “high technology”. Forty grams of PETN, a purportedly dangerous amount, would fit in a 1.25 mm-thick pancake of the dimensions simulated here and be virtually invisible. Packed in a compact mode, say, a 1 cm×4 cm×5 cm brick, it would be detected.

EDITED TO ADD (1/12): Stephen Colbert on the issue.

Posted on December 17, 2010 at 2:13 PM • View Comments

Profiling Lone Terrorists

Masters Thesis from the Naval Postgraduate School: “Patterns of Radicalization: Identifying the Markers and Warning Signs of Domestic Lone Wolf Terrorists in Our Midst.”

Abstract:

This thesis will scrutinize the histories of our nation’s three most prolific domestic lone wolf terrorists: Tim McVeigh, Ted Kaczynski, and Eric Rudolph. It will establish a chronological pattern to their radicalization and reveal that their communal ideological beliefs, psychology, attributes, traits, and training take place along a common chronological timeline. Their pattern of radicalization can be used as an indicator of lone wolf terrorist radicalization development in future cases. This thesis establishes a strikingly similar chronological pattern of radicalization that was present in each terrorist’s biography. This pattern can identify future lone wolf terrorist radicalization activity upstream. It can provide a valuable portent to apply in the analysis of potential lone terrorists, potentially enabling law enforcement to prevent tragedies emerging from the identified population through psychological assistance, evaluation, training, or, in the worst case, detention.

Paper.

Posted on December 7, 2010 at 6:43 AM • View Comments

Control Fraud

I had never heard the term “control fraud” before:

Control fraud theory was developed in the savings and loan debacle. It explained that the person controlling the S&L (typically the CEO) posed a unique risk because he could use it as a weapon.

The theory synthesized criminology (Wheeler and Rothman 1982), economics (Akerlof 1970), accounting, law, finance, and political science. It explained how a CEO optimized “his” S&L as a weapon to loot creditors and shareholders. The weapon of choice was accounting fraud. The company is the perpetrator and a victim. Control frauds are optimal looters because the CEO has four unique advantages. He uses his ability to hire and fire to suborn internal and external controls and make them allies. Control frauds consistently get “clean” opinions for financial statements that show record profitability when the company is insolvent and unprofitable. CEOs choose top-tier auditors. Their reputation helps deceive creditors and shareholders.

Only the CEO can optimize the company for fraud.

This is an interesting paper about control fraud. It’s by William K. Black, the Executive Director of the Institute for Fraud Prevention. “Individual ‘control frauds’ cause greater losses than all other forms of property crime combined. They are financial super-predators.” Black is talking about control fraud by both heads of corporations and heads of state, so that’s almost certainly a true statement. His main point, though, is that our legal systems don’t do enough to discourage control fraud.

White-collar criminology has a set of empirical findings and theories that are useful to understanding when markets will act perversely. This paper addresses three, interrelated theories economists should know about. “Control fraud” theory explains why the most damaging forms of fraud are situations in which those that control the company or the nation use it as a fraud vehicle. The CEO, or the head of state, poses the greatest fraud risk. A single large control fraud can cause greater financial losses than all other forms of property crime combined they are the “super-predators” of the financial world. Control frauds can also occur in waves that can cause systemic economic injury and discredit other institutions essential to good government and society. Control frauds are commonly able to defeat for several years market mechanisms that neo-classical economists predict will prevent such frauds.

“Systems capacity” theory examines why under deterrence is so common. It shows that, particularly with respect to elite crimes, anti-fraud resources and willpower are commonly so limited that “crime pays.” When systems capacity limitations are severe a “criminogenic environment” arises and crime increases. When a criminogenic environment for control fraud occurs it can produce a wave of control fraud.

“Neutralization” theory explores how criminals neutralize moral and social barriers that reduce crime by constraining our decision-making to honest enterprises. The easier individuals are able to neutralize such social restraints, the greater the incidence of crime.

[…]

White-collar criminology findings falsify several neo-classical economic theories. This paper discusses the predictive failures of the efficient markets hypothesis, the efficient contracts hypothesis and the law & economics theory of corporate law. The paper argues that neo-classical economists’ reliance on these flawed models leads them to recommend policies that optimize a criminogenic environment for control fraud. Fortunately, these policies are not routinely adopted in full. When they are, they produce recurrent crises because they eviscerate the institutions and mores vital to make markets and governments more efficient in preventing waves of control fraud. Criminological theories have demonstrated superior predictive and explanatory behavior with regard to perverse economic behavior. This paper discusses two realms of perverse behavior the role of waves of control fraud in producing economic crises and the role that endemic control fraud plays in producing economic stagnation.

EDITED TO ADD (11/11): Related paper on the effects of executive compensation on the abuse of controls.

Posted on November 1, 2010 at 6:02 AM • View Comments

The Politics of Allocating Homeland Security Money to States

From the Journal of Homeland Security and Emergency Management: “Politics or Risks? An Analysis of Homeland Security Grant Allocations to the States.”

Abstract: In the days following the September 11 terrorist attacks on the United States, the nation’s elected officials created the USA Patriot Act. The act included a grant program for the 50 states that was intended to assist them with homeland security and preparedness efforts. However, not long after its passage, critics charged the Department of Homeland Security with allocating the grant funds on the basis of “politics” rather than “risk.” This study analyzes the allocation of funds through all seven of the grant subprograms for the years 2003 through 2006. Conducting a linear regression analysis for each year, our research indicates that the total per capita amounts are inversely related to risk factors but are not related at all to partisan political factors between 2003-2005. In 2006, Congress changed the formula with the intention of increasing the relationship between allocations and risk. However, our findings reveal that this change did not produce the intended effect and the allocations were still negatively related to risk and unrelated to partisan politics.

I’m not sure I buy the methodology, but there it is.

Posted on October 7, 2010 at 7:03 AM • View Comments

Analyzing CAPTCHAs

New research: “Attacks and Design of Image Recognition CAPTCHAs.”

Abstract. We systematically study the design of image recognition CAPTCHAs (IRCs) in this paper. We first review and examine all IRCs schemes known to us and evaluate each scheme against the practical requirements in CAPTCHA applications, particularly in large-scale real-life applications such as Gmail and Hotmail. Then we present a security analysis of the representative schemes we have identified. For the schemes that remain unbroken, we present our novel attacks. For the schemes for which known attacks are available, we propose a theoretical explanation why those schemes have failed. Next, we provide a simple but novel framework for guiding the design of robust IRCs. Then we propose an innovative IRC called Cortcha that is scalable to meet the requirements of large-scale applications. Cortcha relies on recognizing an object by exploiting its surrounding context, a task that humans can perform well but computers cannot. An infinite number of types of objects can be used to generate challenges, which can effectively disable the learning process in machine learning attacks. Cortcha does not require the images in its image database to be labeled. Image collection and CAPTCHA generation can be fully automated. Our usability studies indicate that, compared with Google’s text CAPTCHA, Cortcha yields a slightly higher human accuracy rate but on average takes more time to solve a challenge.

The paper attacks IMAGINATION (designed at Penn State around 2005) and ARTiFACIAL (designed at MSR Redmond around 2004).

Posted on October 5, 2010 at 7:22 AM • View Comments

Cultural Cognition of Risk

This is no surprise:

The people behind the new study start by asking a pretty obvious question: “Why do members of the public disagree—­sharply and persistently—­about facts on which expert scientists largely agree?” (Elsewhere, they refer to the “intense political contestation over empirical issues on which technical experts largely agree.”) In this regard, the numbers from the Pew survey are pretty informative. Ninety-seven percent of the members of the American Association for the Advancement of Science accept the evidence for evolution, but at least 40 percent of the public thinks that major differences remain in scientific opinion on this topic. Clearly, the scientific community isn’t succeeding in making the public aware of its opinion.

According to the new study, this isn’t necessarily the fault of the scientists, though. The authors favor a model, called the cultural cognition of risk, which “refers to the tendency of individuals to form risk perceptions that are congenial to their values.” This wouldn’t apply directly to evolution, but would to climate change: if your cultural values make you less likely to accept the policy implications of our current scientific understanding, then you’ll be less likely to accept the science.

But, as the authors note, opponents of a scientific consensus often try to claim to be opposing it on scientific, rather than cultural grounds. “Public debates rarely feature open resistance to science,” they note, “the parties to such disputes are much more likely to advance diametrically opposed claims about what the scientific evidence really shows.” To get there, those doing the arguing must ultimately be selective about what evidence and experts they accept—­they listen to, and remember, those who tell them what they want to hear. “The cultural cognition thesis predicts that individuals will more readily recall instances of experts taking the position that is consistent with their cultural predisposition than ones taking positions inconsistent with it,” the paper suggests.

[…]

So, it’s not just a matter of the public not understanding the expert opinions of places like the National Academies of science; they simply discount the expertise associated with any opinion they’d rather not hear.

Here’s the paper.

Posted on September 28, 2010 at 6:33 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.