  Energy, water, health, transportation and emergency services act as backbones
for our society. Aiming at high degrees of efficiency, these systems are
increasingly automated, depending on communication systems. However, this makes
these Critical Infrastructures (CI) prone to cyber attacks, resulting in data
leaks, reduced performance or even total system failure. Beyond a survey of
existing vulnerabilities, we provide an experimental evaluation of targeted
uplink jamming against LTE's air interface. Primarily, our implementations of
smart attacks on the LTE Physical Uplink Control Channel (PUCCH), the Physical
Uplink Shared Channel (PUSCH) as well as on the radio access procedure are
outlined and tested. In exploiting the unencrypted resource assignment process,
these attacks are able to target and jam specific UE resources, effectively
denying uplink access. Evaluation results reveal the criticality of such
attacks, severely destabilizing CI, while minimizing attacker exposure. Finally
we derive possible mitigations and recommendations for 5G stakeholders, which
serve to improve the robustness of mission critical communications and enable
the design of resilient next generation mobile networks.
