Entries Tagged "authentication"

Page 16 of 28

Second SHB Workshop Liveblogging (5)

David Livingstone Smith moderated the fourth session, about (more or less) methodology.

Angela Sasse, University College London (suggested reading: The Compliance Budget: Managing Security Behaviour in Organisations; Human Vulnerabilities in Security Systems), has been working on usable security for over a dozen years. As part of a project called “Trust Economics,” she looked at whether people comply with security policies and why they either do or do not. She found that there is a limit to the amount of effort people will make to comply—this is less actual cost and more perceived cost. Strict and simple policies will be complied with more than permissive but complex policies. Compliance detection, and reward or punishment, also affect compliance. People justify noncompliance by “frequently made excuses.”

Bashar Nuseibeh, Open University (suggested reading: A Multi-Pronged Empirical Approach to Mobile Privacy Investigation; Security Requirements Engineering: A Framework for Representation and Analysis), talked about mobile phone security; specifically, Facebook privacy on mobile phones. He did something clever in his experiments. Because he wasn’t able to interview people at the moment they did something—he worked with mobile users—he asked them to provide a “memory phrase” that allowed him to effectively conduct detailed interviews at a later time. This worked very well, and resulted in all sorts of information about why people made privacy decisions at that earlier time.

James Pita, University of Southern California (suggested reading: Deployed ARMOR Protection: The Application of a Game Theoretic Model for Security at the Los Angeles International Airport), studies security personnel who have to guard a physical location. In his analysis, there are limited resources—guards, cameras, etc.—and a set of locations that need to be guarded. An example would be the Los Angeles airport, where a finite number of K-9 units need to guard eight terminals. His model uses a Stackelberg game to minimize predictability (otherwise, the adversary will learn it and exploit it) while maximizing security. There are complications—observational uncertainty and bounded rationally on the part of the attackers—which he tried to capture in his model.

Markus Jakobsson, Palo Alto Research Center (suggested reading: Male, late with your credit card payment, and like to speed? You will be phished!; Social Phishing; Love and Authentication; Quantifying the Security of Preference-Based Authentication), pointed out that auto insurers ask people if they smoke in order to get a feeling for whether they engage in high-risk behaviors. In his experiment, he selected 100 people who were the victim of online fraud and 100 people who were not. He then asked them to complete a survey about different physical risks such as mountain climbing and parachute jumping, financial risks such as buying stocks and real estate, and Internet risks such as visiting porn sites and using public wi-fi networks. He found significant correlation between different risks, but I didn’t see an overall pattern emerge. And in the discussion phase, several people had questions about the data. More analysis, and probably more data, is required. To be fair, he was still in the middle of his analysis.

Rachel Greenstadt, Drexel University (suggested reading: Practical Attacks Against Authorship Recognition Techniques (pre-print); Reinterpreting the Disclosure Debate for Web Infections), discussed ways in which humans and machines can collaborate in making security decisions. These decisions are hard for several reasons: because they are context dependent, require specialized knowledge, are dynamic, and require complex risk analysis. And humans and machines are good at different sorts of tasks. Machine-style authentication: This guy I’m standing next to knows Jake’s private key, so he must be Jake. Human-style authentication: This guy I’m standing next to looks like Jake and sounds like Jake, so he must be Jake. The trick is to design systems that get the best of these two authentication styles and not the worst. She described two experiments examining two decisions: should I log into this website (the phishing problem), and should I publish this anonymous essay or will my linguistic style betray me?

Mike Roe, Microsoft, talked about crime in online games, particularly in Second Life and Metaplace. There are four classes of people on online games: explorers, socializers, achievers, and griefers. Griefers try to annoy socializers in social worlds like Second Life, or annoy achievers in competitive worlds like World of Warcraft. Crime is not necessarily economic; criminals trying to steal money is much less of a problem in these games than people just trying to be annoying. In the question session, Dave Clark said that griefers are a constant, but economic fraud grows over time. I responded that the two types of attackers are different people, with different personality profiles. I also pointed out that there is another kind of attacker: achievers who use illegal mechanisms to assist themselves.

In the discussion, Peter Neumann pointed out that safety is an emergent property, and requires security, reliability, and survivability. Others weren’t so sure.

Adam Shostack’s liveblogging is here. Ross Anderson’s liveblogging is in his blog post’s comments. Matt Blaze’s audio is here.

Conference dinner tonight at Legal Seafoods. And four more sessions tomorrow.

Posted on June 11, 2009 at 4:50 PM • View Comments

Second SHB Workshop Liveblogging (4)

Session three was titled “Usability.” (For the record, the Stata Center is one ugly building.)

Andrew Patrick, NRC Canada until he was laid off four days ago (suggested reading: Fingerprint Concerns: Performance, Usability, and Acceptance of Fingerprint Biometric Systems), talked about biometric systems and human behavior. Biometrics are used everywhere: for gym membership, at Disneyworld, at international borders. The government of Canada is evaluating using iris recognition at a distance for events like the 2010 Olympics. There are two different usability issues: with respect to the end user, and with respect to the authenticator. People’s acceptance of biometrics is very much dependent on the context. And of course, biometrics are not secret. Patrick suggested that to defend ourselves against this proliferation of using biometrics for authentication, the individual should publish them. The rationale is that we’re publishing them anyway, so we might as well do it knowingly.

Luke Church, Cambridge University (suggested reading: SHB Position Paper; Usability and the Common Criteria), talked about what he called “user-centered design.” There’s a economy of usability: “in order to make some things easier, we have to make some things harder”—so it makes sense to make the commonly done things easier at the expense of the rarely done things. This has a lot of parallels with security. The result is “appliancisation” (with a prize for anyone who come up with a better name): the culmination of security behaviors and what the system can do embedded in a series of user choices. Basically, giving users meaningful control over their security. Luke discussed several benefits and problems with the approach.

Diana Smetters, Palo Alto Research Center (suggested reading: Breaking out of the browser to defend against phishing attacks; Building secure mashups; Ad-hoc guesting: when exceptions are the rule), started with these premises: you can teach users, but you can’t teach them very much, so you’d better carefully design systems so that you 1) minimize what they have to learn, 2) make it easier for them to learn it, and 3) maximize the benefit from what they learn. Too often, security is at odds with getting the job done. “As long as configuration errors (false alarms) are common, any technology that requires users to observe security indicators and react to them will fail as attacks can simply masquerade as errors, and users will rationally ignore them.” She recommends meeting the user halfway by building new security models that actually fit the users’ needs. (For example: Phishing is a mismatch problem, between what’s in the user’s head and where the URL is actually going. SSL doesn’t work, but how should websites authenticate themselves to users? Her solution is protected links: a set of secure bookmarks in protected browsers. She went on to describe a prototype and tests run with user subjects.

Jon Callas, PGP Corporation (suggested reading: Improving Message Security with a Self-Assembling PKI), used the metaphor of the “security cliff”: you have to keep climbing until you get to the top and that’s hard, so it’s easier to just stay at the bottom. He wants more of a “security ramp,” so people can reasonably stop somewhere in the middle. His idea is to have a few policies—e-mail encryption, rules about USB drives—and enforce them. This works well in organizations, where IT has dictatorial control over user configuration. If we can’t teach users much, we need to enforce policies on users.

Rob Reeder, Microsoft (suggested reading: Expanding Grids for Visualizing and Authoring Computer Security Policies), presented a possible solution to the secret questions problem: social authentication. The idea is to use people you know (trustees) to authenticate who you are, and have them attest to the fact that you lost your password. He went on to describe how the protocol works, as well as several potential attacks against the protocol and defenses, and experiments that tested the protocol. In the question session he talked about people designating themselves as trustees, and how that isn’t really a problem.

Lorrie Cranor, Carnegie Mellon University (suggested reading: A Framework for Reasoning about the Human in the Loop; Timing Is Everything? The Effects of Timing and Placement of Online Privacy Indicators; School of Phish: A Real-Word Evaluation of Anti-Phishing Training; You’ve Been Warned: An Empirical Study of the Effectiveness of Web Browser Phishing Warnings), talked about security warnings. The best option is to fix the hazard; the second best is to guard against it—but far too often we just warn people about it. But since hazards are generally not very hazardous, most people just ignore them. “Often, software asks the user and provides little or no information to help user make this decision.” Better is to use some sort of automated analysis to assist the user in responding to warnings. For websites, for example, the system should block sites with a high probability of danger, not bother users if there is a low probably of danger, and help the user make the decision in the grey area. She went on to describe a prototype and user studies done with the prototype; her paper will be presented at USENIX Security in August.

Much of the discussion centered on how bad the problem really is, and how much security is good enough. The group also talked about economic incentives companies have to either fix or ignore security problems, and whether market approaches (or, as Jean Camp called it, “the happy Libertarian market pony”) are sufficient. Some companies have incentives to convince users to do the wrong thing, or at the very least to do nothing. For example, social networking sites are more valuable if people share their information widely.

Further discussion was about whitelisting, and whether it worked or not. There’s the problem of the bad guys getting on the whitelist, and the risk that organizations like the RIAA will use the whitelist to enforce copyright, or that large banks will use the whitelist as a tool to block smaller start-up banks. Another problem is that the user might not understand what a whitelist signifies.

Dave Clark from the audience: “It’s not hard to put a seat belt on, and if you need a lesson, take a plane.”

Kind of a one-note session. We definitely need to invite more psych people.

Adam Shostack’s liveblogging is here. Ross Anderson’s liveblogging is in his blog post’s comments. Matt Blaze’s audio is here.

Posted on June 11, 2009 at 2:56 PM • View Comments

Secret Questions

In 2004, I wrote about the prevalence of secret questions as backup passwords. The problem is that the answers to these “secret questions” are often much easier to guess than random passwords. Mother’s maiden name isn’t very secret. Name of first pet, name of favorite teacher: there are some common names. Favorite color: I could probably guess that in no more than five attempts.

The result is that the normal security protocol (passwords) falls back to a much less secure protocol (secret questions). And the security of the entire system suffers.

Here’s some actual research on the issue:

It’s no secret: Measuring the security and reliability of authentication via ‘secret’ questions

Abstract:

All four of the most popular webmail providers—AOL, Google, Microsoft, and Yahoo!—rely on personal questions as the secondary authentication secrets used to reset account passwords. The security of these questions has received limited formal scrutiny, almost all of which predates webmail. We ran a user study to measure the reliability and security of the questions used by all four webmail providers. We asked participants to answer these questions and then asked their acquaintances to guess their answers. Acquaintance with whom participants reported being unwilling to share their webmail passwords were able to guess 17% of their answers. Participants forgot 20% of their own answers within six months. What’s more, 13% of answers could be guessed within five attempts by guessing the most popular answers of other participants, though this weakness is partially attributable to the geographic homogeneity of our participant pool.

Posted on May 25, 2009 at 9:56 AM • View Comments

A Sad Tale of Biometrics Gone Wrong

From The Daily WTF:

Johnny was what you might call a “gym rat.” In incredible shape from almost-daily gym visits, a tight Lycra tank top, iPod strapped to his sizable bicep, underneath which was a large black tribal tattoo. He scanned his finger on his way out, but the turnstile wouldn’t budge.

“Uh, just a second,” the receptionist furiously typed and clicked, while Johnny removed one of his earbuds out and stared. “I’ll just have to manually override it…” but it was useless. There was no manual override option. Somehow, it was never considered that the scanner would malfunction. After several seconds of searching and having Johnny try to scan his finger again, the receptionist instructed him just to jump over the turnstile.

It was later discovered that the system required a “sign in” and a “sign out,” and if a member was recognized as someone else when attempting to sign out, the system rejected the input, and the turnstile remained locked in position. This was not good.

The scene repeated itself several times that day. Worse, the fingerprint scanner at the exit was getting kind of disgusting. Dozens of sweaty fingerprints required the scanner to be cleaned hourly, and even after it was freshly cleaned, it sometimes still couldn’t read fingerprints right. The latticed patterns on the barbell grips would leave indented patterns temporarily on the members’ fingers, there could be small cuts or folds on fingertips just from carrying weights or scrapes on the concrete coming out of the pool, fingers were wrinkly after a long swim, or sometimes the system just misidentified the person for no apparent reason.

Me on biometrics.

Posted on April 30, 2009 at 6:19 AM • View Comments

Fingerprinting Paper

Interesting paper:

Fingerprinting Blank Paper Using Commodity Scanners

Will Clarkson, Tim Weyrich, Adam Finkelstein, Nadia Heninger, Alex Halderman, and Edward W. Felten

Abstract: This paper presents a novel technique for authenticating physical documents based on random, naturally occurring imperfections in paper texture. We introduce a new method for measuring the three-dimensional surface of a page using only a commodity scanner and without modifying the document in any way. From this physical feature, we generate a concise fingerprint that uniquely identifies the document. Our technique is secure against counterfeiting and robust to harsh handling; it can be used even before any content is printed on a page. It has a wide range of applications, including detecting forged currency and tickets, authenticating passports, and halting counterfeit goods. Document identification could also be applied maliciously to de-anonymize printed surveys and to compromise the secrecy of paper ballots.

Posted on March 19, 2009 at 6:07 AM • View Comments

More European Chip and Pin Insecurity

“Optimised to Fail: Card Readers for Online Banking,” by Saar Drimer, Steven J. Murdoch, and Ross Anderson.

Abstract

The Chip Authentication Programme (CAP) has been introduced by banks in Europe to deal with the soaring losses due to online banking fraud. A handheld reader is used together with the customer’s debit card to generate one-time codes for both login and transaction authentication. The CAP protocol is not public, and was rolled out without any public scrutiny. We reverse engineered the UK variant of card readers and smart cards and here provide the first public description of the protocol. We found numerous weaknesses that are due to design errors such as reusing authentication tokens, overloading data semantics, and failing to ensure freshness of responses. The overall strategic error was excessive optimisation. There are also policy implications. The move from signature to PIN for authorising point-of-sale transactions shifted liability from banks to customers; CAP introduces the same problem for online banking. It may also expose customers to physical harm.

EDITED TO ADD (3/12): More info.

Posted on March 5, 2009 at 12:45 PM • View Comments

Michael Froomkin on Identity Cards

University of Miami law professor Michael Froomkin writes about ID cards and society in “Identity Cards and Identity Romanticism.”

This book chapter for “Lessons from the Identity Trail: Anonymity, Privacy and Identity in a Networked Society” (New York: Oxford University Press, 2009)—a forthcoming comparative examination of approaches to the regulation of anonymity edited by Ian Kerr—discusses the sources of hostility to National ID Cards in common law countries. It traces that hostility in the United States to a romantic vision of free movement and in England to an equally romantic vision of the ‘rights of Englishmen’.

Governments in the United Kingdom, United States, Australia, and other countries are responding to perceived security threats by introducing various forms of mandatory or nearly mandatory domestic civilian national identity documents. This chapter argues that these ID cards pose threats to privacy and freedom, especially in countries without strong data protection rules. The threats created by weak data protection in these new identification schemes differ significantly from previous threats, making the romantic vision a poor basis from which to critique (highly flawed) contemporary proposals.

One small excerpt:

…it is important to note that each ratchet up in an ID card regime—the introduction of a non-mandatory ID card scheme, improvements to authentication, the transition from an optional regime to a mandatory one, or the inclusion of multiple biometric identifiers—increases the need for attention to how the data collected at the time the card is created will be stored and accessed. Similarly, as ID cards become ubiquitous, a de facto necessity even when not required de jure, the card becomes the visible instantiation of a large, otherwise unseen, set of databases. If each use of the card also creates a data trail, the resulting profile becomes an ongoing temptation to both ordinary and predictive profiling.

Posted on March 4, 2009 at 7:25 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.