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Bosch Smart Thermostat Feels the Heat From Firmware Bug

The vulnerability in a popular hospitality industry gadget allows attackers to take over the device, pivot into the user's network, or brick the device entirely, rendering HVAC unusable.

3 Min Read
The Bosch BBC100 smart Wi-Fi thermostat
Source: Bosch

A critical vulnerability has been discovered in the widely used, Web-connected Bosch BCC100 thermostat, which is a popular device in hospitality environments.

Exploiting this flaw (CVE-2023-49722) could lead to local unauthorized access, enabling attackers to infiltrate the user's network.

According to a Bitdefender report last week, the vulnerability, which affects software versions 1.7.0 – HD Version 4.13.22, exists in the device's Wi-Fi microcontroller and allows potential attackers to execute malicious commands.

A threat actor would also be able to either replace the device's operating system firmware with a rogue one or "brick" the device, preventing it from booting up and rendering it completely inoperable.

While the thermostat is still on the wall, it would be impossible for the user to modify temperature and working modes.

"This vulnerability is unique in the way that it allows an attacker on the network to instruct the thermostat to wipe itself out and install an operating system as per the attacker's instructions," explains Bogdan Botezatu, director of threat research and reporting at Bitdefender.

A Range of Possible Smart Thermostat Attacks

There are other possible attacks. For example, a hacker could plant a backdoor within the original operating system of the thermostat to be able to connect to the network from the outside and control the device and HVAC commands.

But in the worst-case scenario, an attacker could replace the original firmware with a Linux distribution of their choice and use this newly acquired foothold into the network to sniff traffic or pivot on other devices.

Bosch has issued a fix. Botezatu says that to prevent attacks, firmware updates should be installed as they become available — this is important because vendors constantly work with security researchers to identify and fix vulnerabilities in their products.

"Additionally, it would be extremely helpful if users of IoT technology set up their devices on a dedicated network that is isolated from the private or guest networks already in use," he says.

He adds that customers or guests should not be allowed to scan the Internet of Things (IoT) network or interact with these IoT devices in any way, as they might attempt to run port-scans and known exploits to subvert potentially vulnerable devices.

IoT Attacks Rising as Vulnerabilities Exposed

IoT attacks are on the rise as smart devices see increased adoption and manufacturers focus on bringing smart products to market.

In December, dozens of patches were issued for Apple's popular smartwatches and Apple TVs, while Hikvision intercoms, used in thousands of apartments and offices across the world, were found to be susceptible to spyware.

In March 2023, researchers discovered major security vulnerabilities in video-enabled smart intercoms made by Chinese company Akuvox, allowing audio and video spying.

"Smart devices are quickly becoming the only viable option for end users [in certain ecosystems]," Botezatu says. "Our research and landscape reports show that a significant pool of smart devices are vulnerable and easy to attack, because for many manufacturers, secure devices are secondary to fast market penetration."

He says this is why both the EU and the US are working to pass regulations that call for cybersecurity certifications for Internet-connected devices.

"Users should understand that there are real possibilities unsecured smart devices might be compromised, and that they are easy for cybercriminals to find through widely available scanning tools," Botezatu explains.

He adds that the best way to protect gadgets against known and unknown threats is through security solutions deployed at the router or gateway level.

About the Author(s)

Nathan Eddy, Contributing Writer

Nathan Eddy is a freelance journalist and award-winning documentary filmmaker specializing in IT security, autonomous vehicle technology, customer experience technology, and architecture and urban planning. A graduate of Northwestern University’s Medill School of Journalism, Nathan currently lives in Berlin, Germany.

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