CVE-2019-11712

POST requests made by NPAPI plugins, such as Flash, that receive a status 308 redirect response can bypass CORS requirements. This can allow an attacker to perform Cross-Site Request Forgery (CSRF) attacks. This vulnerability affects Firefox ESR < 60.8, Firefox < 68, and Thunderbird < 60.8.

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.

Affected Software

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]

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

References

• http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00055.html
• http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00058.html
• http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00073.html
• http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00009.html
• http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00010.html
• https://bugzilla.mozilla.org/show_bug.cgi?id=1543804
• https://lists.debian.org/debian-lts-announce/2019/08/msg00001.html
• https://lists.debian.org/debian-lts-announce/2019/08/msg00002.html
• https://security.gentoo.org/glsa/201908-12
• https://security.gentoo.org/glsa/201908-20
• https://www.mozilla.org/security/advisories/mfsa2019-21/
• https://www.mozilla.org/security/advisories/mfsa2019-22/
• https://www.mozilla.org/security/advisories/mfsa2019-23/