Episode 58: Youssef Sammouda - Client-Side & ATO War Stories
Critical Thinking - Bug Bounty Podcast15 Helmi 2024

Episode 58: Youssef Sammouda - Client-Side & ATO War Stories

Episode 58: In this episode of Critical Thinking - Bug Bounty Podcast we finally sit down with Youssef Samouda and grill him on his various techniques for finding and exploiting client-side bugs and postMessage vulnerabilities. He shares some crazy stories about race conditions, exploiting hash change events, and leveraging scroll to text fragments.

Follow us on twitter at: @ctbbpodcast

We're new to this podcasting thing, so feel free to send us any feedback here: info@criticalthinkingpodcast.io

Shoutout to YTCracker for the awesome intro music!

------ Links ------

Follow your hosts Rhynorater & Teknogeek on twitter:

https://twitter.com/0xteknogeek

https://twitter.com/rhynorater

------ Ways to Support CTBBPodcast ------

Sign up for Caido using the referral code CTBBPODCAST for a 10% discount.

Hop on the CTBB Discord at https://ctbb.show/discord!

We also do Discord subs at $25, $10, $5 - premium subscribers get access to private masterclasses, exploits, tools, scripts, un-redacted bug reports, etc.

Today’s Guest: https://twitter.com/samm0uda?lang=en

https://ysamm.com/

Resources:

Client-side race conditions with postMessage:

https://ysamm.com/?p=742

Transferable Objects

https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Transferable_objects

Every known way to get references to windows, in javascript:

https://bluepnume.medium.com/every-known-way-to-get-references-to-windows-in-javascript-223778bede2d

Youssef’s interview with BBRE

https://www.youtube.com/watch?v=MXH1HqTFNm0

Timestamps:

(00:00:00) Introduction

(00:04:27) Client-side race conditions with postMessage

(00:18:12) On Hash Change Events and Scroll To Text Fragments

(00:32:00) Finding, documenting, and reporting complex bugs

(00:37:32) PostMessage Methodology

(00:45:05) Youssef's Vuln Story

(00:53:42) Where and how to look for ATO vulns

(01:05:21) MessagePort

(01:14:37) Window frame relationships

(01:20:24) Recon and JS monitoring

(01:37:03) Client-side routing

(01:48:05) MITMProxy

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