Cross-Site Request Forgery (CSRF) vulnerability in the OAuth implementation of the Tuya SDK 6.5.0 for Android and iOS, affects the Tuya Smart and Smartlife mobile applications, as well as other third-party applications that integrate the SDK, allows an attacker to link their own Amazon Alexa account to a victims Tuya account. The applications fail to validate the OAuth state parameter during the account linking flow, enabling a cross-site request forgery (CSRF)-like attack. By tricking the victim into clicking a crafted authorization link, an attacker can complete the OAuth flow on the victims behalf, resulting in unauthorized Alexa access to the victims Tuya-connected devices. This affects users regardless of prior Alexa linkage and does not require the Tuya application to be active at the time. Successful exploitation may allow remote control of devices such as cameras, doorbells, door locks, or alarms.
Weakness
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
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 [REF-1482].
- 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