CVE-2018-25396

Vulnerability

Heatmiser Wifi Thermostat version 1.7 (and possibly earlier versions) contains a credential disclosure vulnerability in the networkSetup.htm page. This page, intended for network configuration, returns HTML form fields containing the administrative username and password in plaintext. No authentication is required to access this endpoint, making the credentials accessible to any unauthenticated attacker who can reach the device's web interface [1][2].

Exploitation

An attacker with network access to the thermostat's web interface (typically on TCP ports 80 or 8081) can exploit this vulnerability by sending a simple HTTP GET request to /networkSetup.htm. The response contains the username and password in plaintext within the HTML form fields. The publicly available exploit script [1] demonstrates this process: it downloads the page, then extracts the values using grep and awk. No authentication, user interaction, or special privileges are required [1][2].

Impact

Successful exploitation yields the administrative credentials for the thermostat's web interface. With these credentials, an attacker gains full administrative control over the device, including the ability to modify temperature schedules, network settings, and other configuration parameters. This could lead to unauthorized changes to the HVAC system, potential denial of service, and, if the thermostat is on an internal network, a foothold for further lateral movement. The confidentiality of the credentials is directly compromised [1][2].

Mitigation

As of the publication date, no official firmware patch has been released by Heatmiser to address this vulnerability. The vendor's website is referenced [1], but no fixed version is available. Mitigation relies on network-level controls: restrict access to the thermostat's web interface to trusted IP addresses only, avoid exposing the device to the internet, and consider placing it on a separate VLAN. Users should monitor for future firmware updates from Heatmiser. This vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog.