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upstart writes in with an IRC submission:

CallStranger vulnerability lets attacks bypass security systems and scan LANs:

A severe vulnerability resides in a core protocol found in almost all internet of things (IoT) devices.

The vulnerability, named CallStranger, allows attackers to hijack smart devices for distributed denial of service (DDoS) attacks, but also for attacks that bypass security solutions to reach and conduct scans on a victim's internal network -- effectively granting attackers access to areas where they normally wouldn't be able to reach.

According to a website dedicated to the CallStranger vulnerability published today, the bug impacts UPnP, which stands for Universal Plug and Play, a collection of protocols that ship on most smart devices.

Also at Ars Technica.

[...] Çadirci says that an attacker can send TCP packets to a remote device that contains a malformed callback header value in UPnP's SUBSCRIBE function.

This malformed header can be abused to take advantage of any smart device that was left connected on the internet, and which supports the UPnP protocols -- such as security cameras, DVRs, printers, routers, and others.

In a CallStranger attack, the hacker effectively targets the device's internet-facing interface, but executes the code on the device's UPnP function, which usually runs on the internally-facing ports only (inside the LAN).

[...] In addition, Çadirci also published proof-of-concept scripts that companies can use to determine if their smart equipment is vulnerable to any of the CallStranger attacks.

The CallStranger security flaw is also tracked as CVE-2020-12695. There are currently around 5.45 million UPnP-capable devices connected to the internet, making this an ideal attack surface for IoT botnets and APTs.

Original Submission