Web spamming, the practice of introducing artificial text and links into web pages to a#ect the results of searches, has been recognized as a major problem for search engines. It is also a serious problem for users because they are not aware of it and they tend to confuse trusting the search engine with trusting the results of a search. In this paper, we first analyze the influence that web spam has on the evolution of the search engines and we identify the strong relationship of spamming methods to propagandistic techniques in society. Our analysis provides a foundation to understanding why spamming works and o#ers new insight on how to address it. In particular, it suggest that one could use anti-propagandistic techniques in the web to recognize spam. The second part of the paper demonstrates such a technique, called backwards propagation of distrust. In society, recognition of an untrustworthy message (in the opinion of a particular person or other social entity) is a reason for questioning the entities that recommend the message. Entities that are found to strongly support untrustworthy messages become untrustworthy themselves. So, social distrust is propagated backwards for a number of steps. Our algorithm simulates this social behavior on the web graph. In our algorithm, starting from an untrustworthy (according to the end user) site s, we examine its trust neighborhood, that is, the neighborhood of sites that link to s in a few steps. Evaluating the sites-members of the neighborhood we identify a biconnected component (BCCs) with a high percentage of untrustworthy sites. BCCs are formed when there are multiple paths to reach s, thus indicating a concerted e#ort to promote s. This is not the case when starting from a trustworthy site. Our tool explores thousands o...

Abstract not found

Summary. Search Engines have greatly influenced the way we experience the web. Since the early days of the web, users have been relying on them to get informed and make decisions. When the web was relatively small, web directories were built and maintained using human experts to screen and categorize pages according to their characteristics. By the mid 1990’s, however, it was apparent that the human expert model of categorizing web pages does not scale. The first search engines appeared and they have been evolving ever since, taking over the role that web directories used to play. But what need makes a search engine evolve? Beyond the financial objectives, there is a need for quality in search results. Search engines know that the quality of their ranking will determine how successful they are. Search results, however, are not simply based on well-designed scientific principles, but they are influenced by web spammers. Web spamming, the practice of introducing artificial text and links into web pages to affect the results of web searches, has been recognized as a major search engine problem. It is also a serious users problem because they are not aware of it and they tend to confuse trusting the search engine with trusting the results of a search. In this paper, we analyze the influence that web spam has on the evolution of the search engines and we identify the strong relationship of spamming methods on the web to propagandistic techniques in society. Our analysis provides a foundation for understanding why spamming works and offers new insight on how to address it. In particular, it suggests that one could use social anti-propagandistic techniques to recognize web spam.

Abstract—Search Engines have greatly influenced the way we experience the web. Since the early days of the web people have been relying on search engines to find useful information. However, their ability to provide useful and unbiased information can be manipulated by Web spammers. Web spamming, the practice of introducing artificial text and links into web pages to affect the results of searches, has been recognized as a major problem for search engines. But it is mainly a serious problem for web users because they tend to confuse trusting the search engine with trusting the results of a search. In this paper, first we discuss the relationship between Web spam in cyber world and social propaganda in the real world. Then, we propose “backwards propagation of distrust, ” as an approach to finding spamming untrustworthy sites. Our approach is inspired by the social behavior associated with distrust. In society, recognition of an untrustworthy entity (person, institution, idea, etc) is a reason for questioning the trustworthiness of those that recommended this entity. People that are found to strongly support untrustworthy entities become untrustworthy themselves. In other words, in the society, distrust is propagated backwards. Our algorithm simulates this social behavior on the web graph with considerable success. Moreover, by respecting the user’s perception of trust through the web graph, our algorithm makes it possible to resolve the moral question of who should be making the decision of weeding out untrustworthy spammers in favor of the user, not the search engine or some higher authority. Our approach can lead to browser-level, or personalized server-side, web filters that work in synergy with the powerful search engines to deliver personalized, trusted web results. An earlier version of this paper was presented at [35].