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Serious Vulnerabilities Found in Wireless Thermostats

Wi-Fi thermostats developed by UK-based company Heatmiser are plagued by several vulnerabilities that can be exploited remotely by a malicious actor, a researcher reported on Saturday.

Wi-Fi thermostats developed by UK-based company Heatmiser are plagued by several vulnerabilities that can be exploited remotely by a malicious actor, a researcher reported on Saturday.

Andrew Tierney revealed on his blog,, that at least nine security issues have been found in Heatmiser Wi-Fi thermostats. The researcher began analyzing the devices after coming across a blog post detailing several vulnerabilities in a discontinued model.

The wireless thermostats produced by Heatmiser can be controlled remotely from a Web browser or mobile apps by forwarding two ports within the user’s router to the device, Tierney said. The recommended ports are port 80 for Web control and port 8068 for mobile apps.

While this enables customers to remotely control their heating systems, it also exposes them to cyberattacks, Tierney warned. The expert noted that port 8068 is mostly used for these devices, so identifying ones accessible from the Internet is not a difficult task. A quick search performed by the researcher using the Shodan search engine revealed that there are roughly 7,000 accessible thermostats.

The first flaw identified by Tierney is that the Web interface for configuring the thermostats has a default username/password combination, namely admin/admin. Furthermore, the default PIN required to access the system from a smartphone or a tablet is “1234.” Even if this PIN is changed by the user, because there is no rate limiting or lockout on port 8068, an attacker could easily perform a brute-force attack considering that there are only 9,999 combinations.

Another serious problem is that when someone is logged in to a device, they can easily access information such as username, password, Wi-Fi SSID and Wi-Fi password. All this data is available in plain text in a form.

The researcher also discovered that while user input is validated and sanitized, this is done only by a piece of JavaScript code, and not by the device itself. This allows an attacker to pass malicious data by sending the requests through a custom client instead of the Web browser.

Wi-Fi thermostats from Heatmiser are also vulnerable to cross-site request forgery (CSRF) attacks, said Tierney.

“I can send a user a link containing a malicious request and the device will blindly carry it out. For example, I could send a request to change the password to one of my choosing in an email, and as long as the user has logged into the thermostat recently, that request will be carried out by the device,” the researcher explained.

Furthermore, authentication works only based on IP addresses. This means that anyone using the same IP address as the device’s owner can access the thermostat simply by visiting its administration page, without the need for login credentials.

The expert has also found that commands to the thermostat can be carried out by sending HTTP POST request to it – no authentication is required. The authentication method itself is highly insecure because it is based on JavaScript, which allows an attacker to easily view sensitive information, including the login password.

The problem is that even if these vulnerabilities are addressed in the firmware, a firmware update requires a special programmer from Heatmiser, and the process involves taking the device apart, the researcher noted.

Tierney reported his findings to the Heatmiser, which has promised to provide customers with an update to address the vulnerabilities. While it’s working on a fix, the company says it has started contacting customers and advising them to close port 80 on their thermostat.

Interestingly, Tierney is not the first researcher to find security issues in Wi-Fi thermostats from Heatmiser. In January 2013, Jean-Louis Persat reported similar vulnerabilities to the company, but his notifications had not been taken seriously.


Written By

Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.

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