Bypassing CSRF token validation
Summary: PortSwigger's research describes how CSRF token validation fails in practice: applications that validate tokens on POST but skip validation on GET, applications that skip validation when the token parameter is omitted entirely, and applications that accept any token from a global pool rather than tying it to the user's session. It also covers tokens tied to a cookie other than the session cookie, and the 'double submit' defense where the server only checks that a request parameter matches a cookie value, both of which an attacker can exploit if the site has any cookie-setting behavior.
Why it matters: Each of these bypasses turns a token that looks present in your code into no protection at all, and the cookie-based variants can be exploited through any other application on the same DNS domain, such as a staging host setting a cookie scoped to the production one.
Read the original at PortSwigger Research ↗
- Topics
- Vulnerabilities & Patching
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