Advisory Weakness Curation

CodeIgniter Shield Vulnerable to SameSite Attackers Bypassing the CSRF Protection ### Impact This vulnerability may allow SameSite Attackers https://canitakeyoursubdomain.name/ to bypass the CodeIgniter4 CSRF protection https://codeigniter4.github.io/userguide/libraries/security.html mechanism with CodeIgniter Shield. For this attack to succeed, the attacker must have direct (or indirect, e.g., XSS) control over a subdomain site (e.g., `https://a.example.com/`) of the target site (e.g., `http://example.com/`). This vulnerability exists whether `Config\Security::$csrfProtection` is `'cookie'` or `'session'`. It is also exploitable whether `Config\Security::$regenerate` is `true` or `false`. ### Patches Upgrade to **CodeIgniter v4.2.3 or later** and **Shield v1.0.0-beta.2 or later**. ### Workarounds Do all of the following: - set `Config\Security::$csrfProtection` to `'session'` - remove old session data right after login (immediately after ID and password match) - regenerate CSRF token right after login (immediately after ID and password match) ### References - CodeIgniter4 CSRF Protection https://codeigniter4.github.io/userguide/libraries/security.html - SameSite Attacks https://canitakeyoursubdomain.name/ - SameSite Cookies https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie/SameSite - The great SameSite confusion https://jub0bs.com/posts/2021-01-29-great-samesite-confusion/ ### For more information If you have any questions or comments about this advisory: * Open an issue or discussion in codeigniter4/shield https://github.com/codeigniter4/shield * Email us at [security@codeigniter.com](mailto:security@codeigniter.com)

Cross-Site Request Forgery (CSRF) Shield is an authentication and authorization framework for CodeIgniter 4. This vulnerability may allow SameSite Attackers https://canitakeyoursubdomain.name/ to bypass the CodeIgniter4 CSRF protection https://codeigniter4.github.io/userguide/libraries/security.html mechanism with CodeIgniter Shield. For this attack to succeed, the attacker must have direct (or indirect, e.g., XSS) control over a subdomain site (e.g., `https://a.example.com/`) of the target site (e.g., `http://example.com/`). Upgrade to **CodeIgniter v4.2.3 or later** and **Shield v1.0.0-beta.2 or later**. As a workaround: set `Config\Security::$csrfProtection` to `'session,'`remove old session data right after login (immediately after ID and password match) and regenerate CSRF token right after login (immediately after ID and password match)

Cross-Site Request Forgery (CSRF) Shield is an authentication and authorization framework for CodeIgniter 4. This vulnerability may allow SameSite Attackers https://canitakeyoursubdomain.name/ to bypass the CodeIgniter4 CSRF protection https://codeigniter4.github.io/userguide/libraries/security.html mechanism with CodeIgniter Shield. For this attack to succeed, the attacker must have direct (or indirect, e.g., XSS) control over a subdomain site (e.g., `https://a.example.com/`) of the target site (e.g., `http://example.com/`). Upgrade to **CodeIgniter v4.2.3 or later** and **Shield v1.0.0-beta.2 or later**. As a workaround: set `Config\Security::$csrfProtection` to `'session,'`remove old session data right after login (immediately after ID and password match) and regenerate CSRF token right after login (immediately after ID and password match)