Archive for the ‘Microsoft Research’ Category

Progressive authentication: deciding when to authenticate on mobile phones

August 11, 2012 Comments off

Progressive authentication: deciding when to authenticate on mobile phones
Source: Microsoft Research

Mobile users are often faced with a trade-off between security and convenience. Either users do not use any security lock and risk compromising their data, or they use security locks but then have to inconveniently authenticate every time they use the device. Rather than exploring a new authentication scheme, we address the problem of deciding when to surface authentication and for which applications. We believe reducing the number of times a user is requested to authenticate lowers the barrier of entry for users who currently do not use any security. Progressive authentication, the approach we propose, combines multiple signals (biometric, continuity, possession) to determine a level of confidence in a user’s authenticity. Based on this confidence level and the degree of protection the user has configured for his applications, the system determines whether access to them requires authentication. We built a prototype running on modern phones to demonstrate progressive authentication and used it in a lab study with nine users. Compared to the state-of-theart, the system is able to reduce the number of required authentications by 42% and still provide acceptable security guarantees, thus representing an attractive solution for users who do not use any security mechanism on their devices.

Measuring and Fingerprinting Click-Spam in Ad Networks

August 6, 2012 Comments off

Measuring and Fingerprinting Click-Spam in Ad Networks
Source: Microsoft Research

Advertising plays a vital role in supporting free websites and smartphone apps. Click-spam, i.e., fraudulent or invalid clicks on online ads where the user has no actual interest in the advertiser’s site, results in advertising revenue being misappropriated by click-spammers. While ad networks take active measures to block click-spam today, the effectiveness of these measures is largely unknown. Moreover, advertisers and third parties have no way of independently estimating or defending against click-spam.

In this paper, we take the first systematic look at click-spam. We propose the first methodology for advertisers to independently measure click-spam rates on their ads. We also develop an automated methodology for ad networks to proactively detect different simultaneous click-spam attacks. We validate both methodologies using data from major ad networks. We then conduct a large-scale measurement study of click-spam across ten major ad networks and four types of ads. In the process, we identify and perform in-depth analysis on seven ongoing click-spam attacks not blocked by major ad networks at the time of this writing. Our findings highlight the severity of the click-spam problem, especially for mobile ads.

Goldilocks and the Two Mobile Devices: Going Beyond All-Or-Nothing Access to a Device’s Applications

July 30, 2012 Comments off

Goldilocks and the Two Mobile Devices: Going Beyond All-Or-Nothing Access to a Device’s Applications
Source: Microsoft Research

Most mobile phones and tablets support only two access control device states: locked and unlocked. We investigated how well all-or-nothing device access control meets the need of users by interviewing 20 participants who had both a smartphone and tablet. We find all-or-nothing device access control to be a remarkably poor fit with users’ preferences. On both phones and tablets, participants wanted roughly half their applications to be available even when their device was locked and half protected by authentication. We also solicited participants’ interest in new access control mechanisms designed specifically to facilitate device sharing. ; Fourteen participantsa majority (14 out of 20) preferred these controls to existing security locks alone. Finally, we gauged participants’ interest in using face and voice biometrics to authenticate to their mobile phone and tablets; participants were surprisingly receptive to biometrics, given that they were also aware of security and reliability limitations.

Learning from GPS Data for Mobile Recommendation

April 13, 2012 Comments off

Learning from GPS Data for Mobile Recommendation
Source: Microsoft Research

With the increasing popularity of location-based services, we have accumulated a lot of location data on the Web. In this paper, we are interested in answering two popular location-related queries in our daily life: 1) if we want to do something such as sightseeing or dining in a large city like Beijing, where should we go? 2) If we want to visit a place such as the Bird’s

Nest in Beijing Olympic park, what can we do there? We develop a mobile recommendation system to answer these queries. In our system, we first model the users’ location and activity histories as a user-location-activity rating tensor1. Because each user has limited data, the resulting rating tensor is essentially very sparse. This makes our recommendation task difficult.

In order to address this data sparsity problem, we propose three algorithms2 based on collaborative filtering. The first algorithm merges all the users’ data together, and uses a collective matrix factorization model to provide general recommendation [3]. The second algorithm treats each user differently and uses a collective tensor and matrix factorization model to provide personalized recommendation [4]. The third algorithm is a new algorithm which further improves our previous two algorithms by using a ranking-based collective tensor and matrix factorization model. Instead of trying to predict the missing entry values as accurately as possible, it focuses on directly optimizing the ranking loss w.r.t. user preferences on the locations and activities. Therefore, it is more consistent with our ultimate goal of ranking locations/activities for recommendations. For these three algorithms, we also exploit some additional information, such as user-user similarities, location features, activity-activity correlations and user-location preferences, to help the CF tasks. We extensively evaluate our algorithms using a real-world GPS dataset collected by 119 users over 2.5 years. We show that all our three algorithms can consistently outperform the competing baselines, and our newly proposed third algorithm can also outperform our other two previous algorithms.

+ Full Paper (PDF)

An Operating System for the Home

April 11, 2012 Comments off
Source:  Microsoft Research
Network devices for the home such as remotely controllable locks, lights, thermostats, cameras, and motion sensors are now readily available and inexpensive. In theory, this enables scenarios like remotely monitoring cameras from a smartphone or customizing climate control based on occupancy patterns. However,in practice today, such smarthome scenarios are limited to expert hobbyists and the rich because of the high overhead of managing and extending current technology. We present HomeOS, a platform that bridges this gap by presenting users and developers with a PC-like abstraction for technology in the home. It presents network devices as peripherals with abstract interfaces, enables cross-device tasks via applications written against these interfaces, and gives users a management interface designed for the home environment. HomeOS already has tens of applications and supports a wide range of devices. It has been running in 12 real homes for 4–8 months, and 42 students have built new applications and added support for additional devices independent of our efforts.

+ Full Paper (PDF)

An Untold Story of Middleboxes in Cellular Networks

August 29, 2011 Comments off

An Untold Story of Middleboxes in Cellular Networks (PDF)
Source: University of Michigan and Microsoft Research

The use of cellular data networks is increasingly popular as network coverage becomes more ubiquitous and many diverse usercontributed mobile applications are available. The growing cellular traffic demand means that cellular network carriers are facing greater challenges to provide users with good network performance and energy ef?ciency, while protecting networks from potential attacks. To better utilize their limited network resources while securing the network and protecting client devices, the carriers have already deployed various network policies that influence traffic behavior. Today, these policies are mostly opaque, though they directly impact application designs and may even introduce network vulnerabilities.

We present NetPiculet, the first tool that unveils carriers’ NAT and firewall policies by conducting intelligent measurement. By running NetPiculet in the major U.S. cellular providers as well as deploying it as a smartphone application in the wild in more than 100 cellular ISPs, we identified the key NAT and firewall policies which have direct implications on performance, energy, and security. For example, NAT boxes and firewalls set timeouts for idle TCP connections, which sometimes cause significant energy waste on mobile devices. Although most carriers today deploy sophisticated firewalls, they are still vulnerable to various attacks such as battery draining and denial of service. These findings can inform developers in optimizing the interaction between mobile applications and cellular networks and also guide carriers in improving their network con?gurations.

Ameliorating Buyer’s Remorse

July 15, 2011 Comments off

Ameliorating Buyer’s Remorse
Source: Microsoft Research

Keeping in pace with the increasing importance of commerce conducted over the Web, several e-commerce websites now provide admirable facilities for helping consumers decide what product to buy and where to buy it. However, since the prices of durable and high-tech products generally fall over time as firms continually introduce products that have enhanced features, a buyer of such products is often faced with a dilemma: Should she buy the product now or wait for cheaper prices?

We present the design and implementation of Prodcast, an experimental system whose goal is to help consumers decide when to buy a product. The system makes use of forecasts of future prices based on price histories of the products, incorporating features such as sales volume, seasonality, and competition in making its recommendation. We describe techniques that are well-suited for this task and present a comprehensive evaluation of their relative merits using retail sales data for electronic products. Our back-testing of the system indicates that the system is capable of helping consumers time their purchase, resulting in significant savings to them.

+ Full Paper (PDF)


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