Malicious cloud provider can intentionally undervolt cloud infrastructure for additional savings on the electricity bill. ARM processors are low power processors which can lead to substantial energy saving for cloud providers. In our scenario we consider a scrooge cloud provider which undervolts its ARM infrastructure for profit. The instances can be undervolted in a stealthy manner by avoiding critical voltage regions. Applications running under critical undervolting conditions can malfunction. These conditions can be exploited by a cloud user to uncover the undervolted instances. For this novel attack scenario we present a detection method for cloud users. The detection method injects non-selectively faults into processes with the intend to crash the cloud instance. Even if the cloud provider can spoof temperature and voltage readings of the processor, the cloud user is capable to uncover undervolted instances. By crashing instances simultaneously using the detection method, the cloud user is covered by the service licence agreement and exposes the scrooge cloud provider.