In preparation for the brave new world of 5G and IoT, the last few years have seen operators make significant investments in their next-generation networks. However, despite spending billions upgrading from a protocol developed in the 70’s (SS7) to Diameter (4G and 5G), flaws exist that allow an attacker to carry out eavesdropping, tracking, fraud, theft and DoS. This research piece outlines, using examples, how next-generation networks can be abused by an attacker and the steps which can be taken to protect against this.