Millions of devices affected by UPnP vulnerability

CallStranger, as the exploit has been named, is most useful for forcing large numbers of devices to participate in distributed denial of service—or DDoS—attacks that overwhelm third-party targets with junk traffic. CallStranger can also be used to exfiltrate data inside networks even when they’re protected by data loss prevention tools that are designed to prevent such attacks. The exploit also allows attackers to scan internal ports which would otherwise be invisible because they’re not exposed to the Internet.