“Since the domain name is literally just the phone number reversed, you can simply flip it back around to get the real number, so I had full phone numbers, timestamps, and the source IP addresses of the DNS resolvers making the requests.”
Five euros for an expired domain bought control of ENUM zones covering Diego Garcia and Ascension Island. Roughly 400,000 queries logged, mostly from American IPs, revealing call metadata to military bases. Nobody attacked anything. A domain lapsed and the phone system kept cheerfully handing out numbers to whoever answered. Someone with worse intentions could have bought it just as easily.