Duen Horng Chau

Learn More
Given a large online network of online auction users and their histories of transactions, how can we spot anomalies and auction fraud? This paper describes the design and implementation of NetProbe, a system that we propose for solving this problem. NetProbe models auction users and transactions as a Markov Random Field tuned to detect the suspicious(More)
Given a large graph, like a computer network, which k nodes should we immunize (or monitor, or remove), to make it as robust as possible against a computer virus attack? We need (a) a measure of the ‘Vulnerability’ of a given network, b) a measure of the ‘Shield-value’ of a specific set of k nodes and (c) a fast algorithm to(More)
Online auctions have gained immense popularity by creating an accessible environment for exchanging goods at reasonable prices. Not surprisingly, malevolent auction users try to abuse them by cheating others. In this paper we propose a novel method, 2-Level Fraud Spotting (2LFS), to model the techniques that fraudsters typically use to carry out fraudulent(More)
Systems of connected appliances, such as home theaters and presentation rooms, are becoming commonplace in our homes and workplaces. These systems are often difficult to use, in part because users must determine how to split the tasks they wish to perform into sub-tasks for each appliance and then find the particular functions of each appliance to complete(More)
Given a huge online social network, how do we retrieve information from it through crawling? Even better, how do we improve the crawling performance by using parallel crawlers that work independently? In this paper, we present the framework of parallel crawlers for online social networks, utilizing a centralized queue. To show how this works in practice, we(More)
We present Polonium, a novel Symantec technology that detects malware through large-scale graph inference. Based on the scalable Belief Propagation algorithm, Polonium infers every file’s reputation, flagging files with low reputation as malware. We evaluated Polonium with a billion-node graph constructed from the largest file submissions dataset ever(More)
Modern applications such as Microsoft Word have many automatic features and hidden dependencies that are frequently helpful but can be mysterious to both novice and expert users. The ""Crystal"" application framework provides an architecture and interaction techniques that allow programmers to create applications that let the user ask a wide variety of(More)
Sometimes people cannot remember the names or locations of things on their computer, but they can remember what <i>other</i> things are associated with them. We created Feldspar, the first system that fully supports this associative retrieval of personal information on the computer. Feldspar's contributions include (1) an intuitive user interface that(More)
If several friends of Smith have committed petty thefts, what would you say about Smith? Most people would not be surprised if Smith is a hardened criminal. Guilt-by-association methods combine weak signals to derive stronger ones, and have been extensively used for anomaly detection and classification in numerous settings (e.g., accounting fraud,(More)
We present the design and implementation of a word-level stroking system called <i>Fisch</i>, which is intended to improve the speed of character-level unistrokes. Importantly, Fisch does not alter the way in which character-level unistrokes are made, but allows users to gradually ramp up to word-level unistrokes by extending their letters in minimal ways.(More)