Web crawlers are complex applications that explore the Web for different purposes. Web crawlers can be configured to crawl online social networks (OSNs) to obtain relevant data about their global structure. Before a web crawler can be launched to explore the Web, a large amount of settings have to be configured. These settings define the crawler's behavior and they have a big impact on the collected data. Both the amount of collected data and the quality of the information that it contains are affected by the crawler settings and, therefore, by properly configuring these web crawler settings we can target specific goals to achieve with our crawl. In this paper, we review the configuration choices that an attacker who wants to obtain information from an OSN by crawling it has to make to conduct his attack. We analyze different scheduler algorithms for web crawlers and evaluate their performance in terms of how useful they are to pursue a set of different adversary goals. © 2013 Wiley Periodicals, Inc.