On BIG-IP Advanced WAF and BIG-IP ASM version 16.0.x before 16.0.1.2 and 15.1.x before 15.1.3 and NGINX App Protect on all versions before 3.5.0, when a cross-site request forgery (CSRF)-enabled policy is configured on a virtual server, an undisclosed HTML response may cause the bd process to terminate. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
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.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Big-ip_advanced_web_application_firewall | F5 | 15.1.0 (including) | 15.1.3.1 (excluding) |
| Big-ip_advanced_web_application_firewall | F5 | 16.0.0 (including) | 16.0.1.2 (excluding) |
| Big-ip_application_security_manager | F5 | 15.1.0 (including) | 15.1.3.1 (excluding) |
| Big-ip_application_security_manager | F5 | 16.0.0 (including) | 16.0.1.2 (excluding) |
| Nginx_app_protect | F5 | 1.0.0 (including) | 1.3.0 (including) |
| Nginx_app_protect | F5 | 2.0.0 (including) | 2.3.0 (including) |
| Nginx_app_protect | F5 | 3.0.0 (including) | 3.5.0 (excluding) |
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]
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/111.html
- https://cwe.mitre.org/data/definitions/462.html
- https://cwe.mitre.org/data/definitions/467.html
- https://cwe.mitre.org/data/definitions/62.html