With 20 million installs a day , third-party apps are a major reason for the popularity and addictiveness of Facebook. Unfortunately, hackers have realized the potential of using apps for spreading malware and spam. The problem is already significant, as we find that at least 13% of apps in our dataset are malicious. So far, the research community has focused on detecting malicious posts and campaigns. In this paper, we ask the question: Given a Facebook application, can we determine if it is malicious? Our key contribution is in developing FRAppE-Facebook's Rigorous Application Evaluator-arguably the first tool focused on detecting malicious apps on Facebook. To develop FRAppE, we use information gathered by observing the posting behavior of 111K Facebook apps seen across 2.2 million users on Facebook. First, we identify a set of features that help us distinguish malicious apps from benign ones. For example, we find that malicious apps often share names with other apps, and they typically request fewer permissions than benign apps. Second, leveraging these distinguishing features, we show that FRAppE can detect malicious apps with 99.5% accuracy, with no false positives and a high true positive rate (95.9%). Finally, we explore the ecosystem of malicious Facebook apps and identify mechanisms that these apps use to propagate. Interestingly, we find that many apps collude and support each other; in our dataset, we find 1584 apps enabling the viral propagation of 3723 other apps through their posts. Long term, we see FRAppE as a step toward creating an independent watchdog for app assessment and ranking, so as to warn Facebook users before installing apps.

Online social networks (OSNs) have become a popular new vector for distributing malware and spam, which we refer to as socware. Unlike email spam, which is sent by spammers directly to intended victims, socware cascades through OSNs as compromised users spread it to their friends. In this paper, we analyze data from the walls of roughly 3 million Facebook users over five months, with the goal of developing a better understanding of socware cascades.

With 20 million installs a day, third-party apps are a major reason for the popularity and addictiveness of Facebook. Unfortunately, hackers have realized the potential of using apps for spreading malware and spam. The problem is already significant, as we find that at least 13% of apps in our dataset are malicious. So far, the research community has focused on detecting malicious posts and campaigns.

Landmark-based routing (LR) provides a promising approach for scalable point-to-point routing in wireless sensor networks (WSNs). Though various approaches have been proposed for landmark-based routing, they either introduce significant computational complexity or are inefficient in realistic, dynamic environments. In this paper, we identify three design principles that could form the basis of efficiency: algorithmic simplicity, update efficiency, and application awareness. Motivated by these principles, we present XLR, a new, flexible and comprehensive framework that tackles the inefficiency of landmark-based routing. XLR consists of four components: Relay Selection (RS), Parametric P-Norm distance function (PPN), Efficient Update with Coordinate Difference (EUCD) and General Forwarding (GF). The key advantage of XLR is that any subset of XLR's components can be independently incorporated into most landmark-based routing protocols.We perform extensive simulations to demonstrate that: (i) RS, a simple method, yields good performance comparable with previous methods, (ii) PPN increases LR performance considerably, (iii) EUCD reduces coordinate update overhead by up to 39%, and (iv) our GF outperforms previous approaches that consider factors such as link quality, delay and power consumption independently.

We propose PRoPHET+, a routing scheme for opportunistic networks designed to maximize successful data delivery rate and minimize transmission delay. PRoPHET+ computes a deliverability value to determine the routing path for packets. Deliverability is calculated using a weighted function consisting of evaluations of nodes' buffer size, power, location, popularity, and the predictability value from PRoPHET. Even though the proposed PRoPHET+'s weights are chosen based on qualitative considerations, it is possible for PRoPHET+ to perform even more efficiently in various environments by shifting the weights accordingly. Our simulation illustrates that PRoPHET+ can perform better or equal to the routing protocol PRoPHET if logical choices for weights are used.

Industry has responded to the ever-growing presence of spam by attacking the spam distribution infrastructure, essentially trying to prevent spam email from ever landing in the inbox of end-users. Recently, industry and academia have begun investigating the web hosting infrastructure of spam campaigns, attacking spammers where it hurts most, in their pocketbooks. Spammers have responded by introducing cooperative interme- diaries that redirect traffic, effectively decoupling the spam-advertised URL from the final destination website. In this study, we analyze not only the URLs in spam messages, but the less-studied redirection infrastructure that takes the user to a target website or other malicious host. Our initial results show that among all the hosts that can be reached directly from URLs embedded in email bodies, 64.87% are cooperative redirection hosts. However, these redirection hosts are only used to protect a small portion (11.33%) of final destination websites. Additionally, we find that around 70% of embedded URLs resolve to two ranges of IP space (61.0.0.0/8 and 124.0.0.0/8). By further analyzing the relationship between the final destinations and redirection hosts, we find that 74.19% of the final destination hosts are located in the same AS with their redirection hosts.

With wireless technologies extending to every part of our daily lives, mobile networking applications are becoming increasingly popular for accessing the Internet. In this paper, we propose a peer-to-peer approach, called M-FTP, for mobile FTP services. Unlike traditional approaches, the proposed scheme implements a Collaborative Forwarding algorithm that takes advantage of opportunistic wireless connections, thereby improving network capacity by exploiting the diversity of network mobility. Using simulations as well as real- world network scenarios, we demonstrate that the proposed scheme provides a better mobile FTP service than traditional schemes, and thus facilitates more effective data transfer on the go.

With wireless technologies extending to every part of our daily lives, mobile networking applications are becoming increasingly popular for accessing the Internet. Among them, Web surfing is one of the most important applications because the World Wide Web has accelerated the dissemination of information and knowledge via the Internet unencumbered by geographic boundaries. In this paper, we propose a peer-to-peer approach, called PPWeb, for mobile Web surfing. Unlike traditional approaches, the proposed scheme implements a collaborative forwarding algorithm that takes advantage of opportunistic wireless connections, thereby improving network capacity by exploiting the diversity of network mobility. Using simulations as well as real-world network scenarios, we demonstrate that the proposed scheme provides a better Web surfing service than traditional schemes, and thus facilitates more effective Web surfing on the go.

We propose a Scalable and Collaborative Internet Access approach, called SCIA, for mobile web surfing. Unlike traditional approaches, the proposed scheme implements a Collaborative Forwarding algorithm that takes advantage of opportunistic wireless connections, and thus improves network capacity by exploiting the diversity of network mobility. Moreover, using the Layered Multiple Description Coding (LMDC) algorithm, the SCIA scheme allows the end user to 'preview' the web content, even before the data has been completely transferred. Using simulations as well as realistic opportunistic people network scenarios, we demonstrate that the SCIA scheme provides a better web surfing service than traditional schemes, and thus facilitates more effective web surfing on the go.

The use of multiple channels in wireless networks could provide performance advantages in reducing collisions and enabling more concurrent transmissions. So et al. proposed a multi-channel MAC protocol, which uses a single transceiver and divides the beacon interval into two parts: channel negotiation and data transmission. However, the fixed length of channel negotiation interval limits the channel utilization. We propose a new single transceiver MAC protocol, named traffic aware multichannel medium access control (TAMMAC), that can exploit multiple channels with smart window increase and decrease rules to adjust the contention window size dynamically and properly. The simulation results show that the proposed protocol achieves higher aggregate network throughput than other schemes under various traffic loads.

Employing multiple channels is an effective way to improve the performance of wireless networks [2-10]. Some previous works on multiple channels [2-4] assume at least two transceivers and result in a higher cost on hardware requirements. The protocol in [5] uses a single transceiver and divides the beacon interval into two parts: channel negotiation and data transmission. However, the fixed length of channel negotiation interval limits the channel utilization. This paper proposed a new single transceiver MAC protocol that can exploit multiple channels effectively and dynamically adjust the length of negotiation interval to better utilize the wireless channel resources. The simulation results show that the proposed protocol achieves higher aggregate network throughput than the fixed schemes on various traffic loads.