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CSRF Resurrections: Starring the Unholy Trinity

Dongsung Kim

Dongsung Kim demonstrates how modern browser features and emerging Web APIs can be chained to resurrect Cross-Site Request Forgery (CSRF) despite SameSite cookies.

Summary

The Premature Declaration of CSRF's Death

With browsers enforcing SameSite=Lax cookie policies by default, many developers assume that Cross-Site Request Forgery (CSRF) has been completely eradicated.

Uncovering SameSite Bypass Vectors

Dongsung Kim analyzes subtle browser behavior quirks, top-level navigation exceptions, and client-side redirects that allow attackers to bypass Lax restrictions.

Chaining the Unholy Trinity of Web Features

Kim demonstrates chaining window opening methods, service worker caches, and navigation timing bugs to reliably execute authenticated state-changing requests.

Robust Defensive Standards for Modern Web Apps

The presentation emphasizes why defense-in-depth—including custom header validation, explicit anti-CSRF tokens, and SameSite=Strict—remains indispensable.

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Main Stage·40 min

  • DEF CON
  • AppSec
  • Date: Aug 2021
  • Location: Las Vegas

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PortSwigger researcher James Kettle pioneers HTTP/2 request smuggling, uncovering critical implementation flaws when front-end reverse proxies downgrade to back-end HTTP/1.1.

http2request-smugglingdesync+2