  Online Social Networks (OSNs) have rapidly become a prominent and widely used
service, offering a wealth of personal and sensitive information with
significant security and privacy implications. Hence, OSNs are also an
important - and popular - subject for research. To perform research based on
real-life evidence, however, researchers may need to access OSN data, such as
texts and files uploaded by users and connections among users. This raises
significant ethical problems. Currently, there are no clear ethical guidelines,
and researchers may end up (unintentionally) performing ethically questionable
research, sometimes even when more ethical research alternatives exist. For
example, several studies have employed `fake identities` to collect data from
OSNs, but fake identities may be used for attacks and are considered a security
issue. Is it legitimate to use fake identities for studying OSNs or for
collecting OSN data for research? We present a taxonomy of the ethical
challenges facing researchers of OSNs and compare different approaches. We
demonstrate how ethical considerations have been taken into account in previous
studies that used fake identities. In addition, several possible approaches are
offered to reduce or avoid ethical misconducts. We hope this work will
stimulate the development and use of ethical practices and methods in the
research of online social networks.
