To accomplish the mammoth task of informing about 50 different vendors and various ISPs we teamed up with CERT/CC (VU#566724). We would really like to report that our efforts were successful, but as it turns out the number of devices on the web using known private keys for HTTPS server certificates has gone up by 40% in the last nine months (3.2 million in November 2015 vs. 4.5 million now). There are many explanations for this development. The inability of vendors to provide patches for security vulnerabilities including but not limited to legacy/EoL products might be a significant factor, but even when patches are available, embedded systems are rarely patched. Insufficient firewalling of devices on the WAN side (by users, but also ISPs in case of ISP-supplied customer premises equipment, CPE) and the trend of IoT-enabled products are surely a factor as well.

Source: SEC Consult: House of Keys: 9 Months later… 40% Worse

This means it’s quite easy to listen in and interfere with these devices as well.