TY - JOUR N2 - Access logs may offer service providers a lot of information about specific users. Depending on the type of the service offers, the operator is capable of obtaining the user’s IP, location, communication habits, device information and so on. In this paper, we analyze a sample instant messenger service that is operating for a certain period of time. In our sandbox, we gathered enough data to correlate user communication habits with their localization, and even contacts. We show how seriously metadata may impact the user’s privacy and make some recommendations about mitigating the quantity of data collected in connection with this type of services. L1 - http://journals.pan.pl/Content/115219/PDF/56_2547_Kaczynski_skl_new1.pdf L2 - http://journals.pan.pl/Content/115219 PY - 2020 IS - No 3 EP - 410 DO - 10.24425/ijet.2020.131892 KW - metadata KW - privacy KW - cybersecurity KW - instant messaging KW - access logs A1 - Glet, Michał A1 - Kaczyński, Kamil PB - Polish Academy of Sciences Committee of Electronics and Telecommunications VL - vol. 66 DA - 2020.09.17 T1 - Access Logs – Underestimated Privacy Risks SP - 405 UR - http://journals.pan.pl/dlibra/publication/edition/115219 T2 - International Journal of Electronics and Telecommunications ER -