According to
Input, a hacker with the pseudonym ‘virtrux’ (previously ‘j3ws3r’) said he gained access by scanning for ports utilized by two systems commonly used in emergency alerts. In doing so, virtrux found millions of IP addresses, which he scanned through for keywords likely used in such alert systems. That further narrowed down the list to thousands.
From there, virtrux says he “social engineered some manufacturers of these [systems] to give me either the service password or the default password.” Social engineering is a tactic used by hackers to manipulate users into divulging credentials or other secure data. After trying a few IPs, virtrux said he gained access.