Entries Tagged "academic papers"

Page 66 of 86

Erasing Data from Flash Drives

“Reliably Erasing Data From Flash-Based Solid State Drives,” by Michael Wei, Laura M. Grupp, Frederick E. Spada, and Steven Swanson.

Abstract: Reliably erasing data from storage media (sanitizing the media) is a critical component of secure data management. While sanitizing entire disks and individual files is well-understood for hard drives, flash-based solid state disks have a very different internal architecture, so it is unclear whether hard drive techniques will work for SSDs as well.

We empirically evaluate the effectiveness of hard drive-oriented techniques and of the SSDs’ built-in sanitization commands by extracting raw data from the SSD’s flash chips after applying these techniques and commands. Our results lead to three conclusions: First, built-in commands are effective, but manufacturers sometimes implement them incorrectly. Second, overwriting the entire visible address space of an SSD twice is usually, but not always, sufficient to sanitize the drive. Third, none of the existing hard drive-oriented techniques for individual file sanitization are effective on SSDs.

This third conclusion leads us to develop flash translation layer extensions that exploit the details of flash memory’s behavior to efficiently support file sanitization. Overall, we find that reliable SSD sanitization requires built-in, verifiable sanitize operations.

News article. Video of talk.

Posted on March 1, 2011 at 6:29 AM • View Comments

Trojan Steals Credit Card Numbers

It’s only a proof of concept, but it’s scary nonetheless. It’s a Trojan for Android phones that looks for credit-card numbers, either typed or spoken, and relays them back to its controller.

Software released for Android devices has to request permissions for each system function it accesses—with apps commonly requesting access to the network, phone call functionality, internal and external storage devices, and miscellaneous hardware functions such as the backlight, LED, or microphone. These requests are grouped into categories and presented to the user at the point of installation—helping to minimise the chance of a Trojan slipping by.

Soundminer takes a novel approach to these restrictions, by only requesting access to ‘Phone calls,’ to read phone state and identity, ‘Your personal information,’ to read contact data, and ‘Hardware controls’ to record audio—none of which will ring alarm bells if the app is marketed as a voice recording tool.

Research paper here. YouTube demo. Another blog post. Research paper; section 7.2 describes some defenses, but I’m not really impressed by any of them.

Posted on January 29, 2011 at 7:45 AM • View Comments

Hacking Tamper-Evident Devices

At the Black Hat conference lasts week, Jamie Schwettmann and Eric Michaud presented some great research on hacking tamper-evident seals.

Jamie Schwettmann and Eric Michaud of i11 Industries went through a long list of tamper evident devices at the conference here and explained, step-by-step, how each seal can be circumvented with common items, such as various solvents, hypodermic needles, razors, blow driers, and in more difficult cases with the help of tools such as drills.

Tamper-evident devices may be as old as civilization, and today are used in everyday products such as aspirin containers’ paper seals. The more difficult devices may be bolt locks designed to secure shipping containers, or polycarbonate locks designed to shatter if cut.

But they all share something in common: They can be removed and the anti-tampering device reassembled.

Here’s their paper, and here are the slides from their presentation. (These two direct download links from GoogleDocs also work.) There was more information in the presentation than in either the paper or the PowerPoint slides. If the video ever gets online, I’ll link to it in this post.

Posted on January 24, 2011 at 1:20 PM • View Comments

The Legality of the Certificate Authority Trust Model

Interesting research:

We looked at the standard legal documents issued by the certificate authorities or “CAs,” including exemplar Subscriber Agreements (agreements between CAs and website operators); “Certification Practice Statements” (statements by CAs outlining their business practices); and Relying Party Agreements (purported agreements between CAs and “relying parties,” such as end-users). What we found was surprising:

  • “Relying Party Agreements” purport to bind end-users to their terms despite the apparent absence of any mechanism to either affirmatively alert the end-user as to the existence of the supposed Agreements or afford the end-user an opportunity to register his or her acceptance or rejection of the Agreements’ terms
  • Certification Practice Statements that suffer from the same problem (i.e. no affirmative notice to the end-user and no meaningful opportunity for acceptance or rejection of terms)

There were other issues as well. For example, the Relying Party Agreements and Certification Practice Statements set forth various obligations on the part of end-users (i.e. “relying parties”) such as: the requirement that end-users make an independent determination of whether it is reasonable to trust a website offering a secure connection (isn’t that the whole point of having a CA, so that the end-user doesn’t have to do that?); the requirement that the end-user be familiar with the crypto software and processes used to carry out the authentication process; and the end-user’s duty to indemnify and hold harmless the CA in the event of legal claims by third parties.

Paper here.

EDITED TO ADD (2/10)> Matt Blaze on CAs.

Posted on January 21, 2011 at 5:31 AM • View Comments

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

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Sidebar photo of Bruce Schneier by Joe MacInnis.