Backdoor attacks allow an attacker to embed functionality jeopardizing proper
behavior of any algorithm, machine learning or not. This hidden functionality
can remain inactive for normal use of the algorithm until activated by the
attacker. Given how stealthy backdoor attacks are, consequences of these
backdoors could be disastrous if such networks were to be deployed for
applications as critical as border or access control. In this paper, we propose
a novel backdoored network detection method based on the principle of anomaly
detection, involving access to the clean part of the training data and the
trained network. We highlight its promising potential when considering various
triggers, locations and identity pairs, without the need to make any
assumptions on the nature of the backdoor and its setup. We test our method on
a novel dataset of backdoored networks and report detectability results with
perfect scores.