Satellites are widely used in our day-to-day life,
which makes them a strategic target. Thus, the security of these
satellites must be seriously considered, as showcased by recent
attacks. A security by-design approach is of course essential,
but complementary security measures are also needed, such as
Intrusion Detection Systems (IDSs). In this paper, we describe the
design of an intrusion detection system embedded in the satellite,
as well as the corresponding threat model. The IDS, still in
development, uses a multi-probe and multi-modules approach, to
be able to face multiple threats. The paper also briefly describes
some attack scenarios that we are currently implementing to
assess the relevance of the IDS. The experiments are carried
out on the NASA Operational Simulator for Small Satellites, the
NOS3 platform.