CVE-2019-17590

The csrf_callback function in the CSRF Magic library through 2016-03-27 is vulnerable to CSRF protection bypass as it allows one to tamper with the csrf token values. A remote attacker can exploit this by crafting a malicious page and dispersing it to a victim via social engineering, enticing them to click the link. Once the user/victim clicks the try again button, the attacker can take over the account and perform unintended actions on the victims behalf. NOTE: A third-party maintainer has stated that this CVE is a false report. They state that the csrf_callback function is actually a callback function to the callers own handler for output. The function called can be changed via configuration to a custom callback to handle failed validation differently. They also stated that there is no way for an attacker to change tokens to make them valid from the client side. The only thing an attack can do is to pull the token out of the javascript, but that will always be possible and has nothing to do with the callback

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

• https://pastebin.com/01tDgq7u