ESPHome is a system to control microcontrollers remotely through Home Automation systems. API endpoints in dashboard component of ESPHome version 2023.12.9 (command line installation) are vulnerable to Cross-Site Request Forgery (CSRF) allowing remote attackers to carry out attacks against a logged user of the dashboard to perform operations on configuration files (create, edit, delete). It is possible for a malicious actor to create a specifically crafted web page that triggers a cross site request against ESPHome, this allows bypassing the authentication for API calls on the platform. This vulnerability allows bypassing authentication on API calls accessing configuration file operations on the behalf of a logged user. In order to trigger the vulnerability, the victim must visit a weaponized page. In addition to this, it is possible to chain this vulnerability with GHSA-9p43-hj5j-96h5/ CVE-2024-27287 to obtain a complete takeover of the user account. Version 2024.3.0 contains a patch for this issue.
Weakness
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.
Potential Mitigations
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, use anti-CSRF packages such as the OWASP CSRFGuard. [REF-330]
- Another example is the ESAPI Session Management control, which includes a component for CSRF. [REF-45]
- Use the “double-submitted cookie” method as described by Felten and Zeller:
- When a user visits a site, the site should generate a pseudorandom value and set it as a cookie on the user’s machine. The site should require every form submission to include this value as a form value and also as a cookie value. When a POST request is sent to the site, the request should only be considered valid if the form value and the cookie value are the same.
- Because of the same-origin policy, an attacker cannot read or modify the value stored in the cookie. To successfully submit a form on behalf of the user, the attacker would have to correctly guess the pseudorandom value. If the pseudorandom value is cryptographically strong, this will be prohibitively difficult.
- This technique requires Javascript, so it may not work for browsers that have Javascript disabled. [REF-331]
References