By Rahul Sami
Nowadays, people often use aggregated information from other users to make judgments about products and people. For example, Amazon.com recommends books to consider buying; Intrade.com provides forecasts of election outcomes; and TripAdvisor.com aggregates users’ hotel ratings. As Internet users increasingly rely on such guidance, there are stronger incentives for people with vested interests to subvert these aggregation systems to promote their own products or candidates. A number of recent cases have highlighted the danger that manipulative attacks pose to information aggregation systems.
One simple but often effective form of attack consists of ballot stuffing in online voting systems. For example, Time magazine annually holds an informal Internet poll to nominate the Time Person of the Year. This poll is often the target of ballot-stuffing campaigns, leading people to view the results with suspicion. Continue reading »