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Logitech Harmony Hub vulnerabilities leave devs fuming

05 Mar 2019
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Logitech has bowed to public pressure and reinstated a developer firmware version of its popular Harmony Hub, after it was revealed that the Hub had critical security flaws.

Harmony Hub is used by millions of people worldwide. It is a home system that connects entertainment and smart home devices to a single touch control. It can connect gaming consoles, smart lights, computers and tablets, CCTV and even door locking systems.

However, four vulnerabilities in the system allow an attacker to take control of the Hub – and all the devices connected to it.

Tenable’s Joseph Bingham explains the details:

“The hub has several services open over 3 ports implementing XMPP, WebSocket, and a custom web API service.”

“The Harmony hub uses a messaging system, whereby functionality is implemented by handlers in the application code that can be called by Logitech’s remote servers when the user is controlling the hub with the smartphone app. These message handling functions control the life-blood of the device as the hub turns up the thermostat at night and unlocks your door when you get home.

“Of course, there is a protection mechanism to ensure that only trusted servers can make requests or use the protected message handling functions. The protection mechanism is flawed, however, allowing any remote attacker to bypass the security measures.

While the hub processes all requests from remote hosts, it tries to verify the origin first. Attackers can forge the origin with a single line in an HTTP header, which means they can bypass validation check and get access to protected message handling.

After a few more technical moves, the attacker can perform an HTTP request to shift the sync server to a server controlled by the attacker themselves.

“The hub will make a request to resynchronise its clock using the newly set server and the attacker and respond with the command injection payload to root the hub.”

Now that the attacker has rooted the Hub and all connected devices, they can modify thermostats, shut down home security systems, and create mayhem.

While Logitech initially fixed the issue by removing its external software interfaces, the decision wasn’t popular with users and developers.

Logitech then introduced an XMPP beta programme that allows developer firmware versions to be installed. The firmware can reinstate the XMPP API as it was – including the security vulnerabilities.

Logitech says it is working on a new Hub firmware fix to patch the vulnerabilities.