[1]https://arstechnica.com/information-technology/2019/05/33-linksys-ro
   uter-models-leak-full-historic-record-of-every-device-ever-connected/
   Independent researcher Troy Mursch said the leak is the result of a
   flaw in almost three dozen models of Linksys routers. It took about 25
   minutes for the Binary Edge search engine of Internet-connected devices
   to find 21,401 vulnerable devices on Friday. A scan earlier in the week
   found 25,617. They were leaking a total of 756,565 unique MAC
   addresses. Exploiting the flaw requires only a few lines of code that
   harvest every MAC address, device name, and operating system that has
   ever connected to each of them.
   The flaw allows snoops or hackers to assemble disparate pieces of
   information that most people assume aren’t public. By combining a
   historical record of devices that have connected to a public IP
   addresses, marketers, abusive spouses, and investigators can track the
   movements of people they want to track. The disclosure can also be
   useful to hackers. The Shadowhammer group, for instance, recently
   infected as many as 1 million people after hacking the software update
   mechanism of computer maker ASUS. The hackers then used a list of about
   600 MAC addresses of specific targets that, if infected, would receive
   advanced stages of the malware.

References

   1. https://arstechnica.com/information-technology/2019/05/33-linksys-router-models-leak-full-historic-record-of-every-device-ever-connected/