This paper presents a scan-based attack on hardware implementations of Elliptic Curve Cryptosystems (ECC). Several up-to-date Design-for-Testability (DfT) features are considered, including response compaction, X-Masking and partial scan. Practical aspects of the proposed scan-based attack are described, namely timing and leakage analysis that allows finding out data related to the secret key among the bits observed through the DfT structures. We use an experimental setup which allows full automation of the proposed scan attack on designs including DfT configurations. We require around 8 chosen points to implement the attack for retrieving a 192-bit scalar.