Tag: Defcon

Fun with sine waves: DEF CON 2025 quals echoid writeup

11 minute read – posted on April 13, 2025 by Zack Orndorff

Overview

I had a great time playing quals this year with Shellphish. I usually try to write full-length stories for my writeups (see my blog archives for a few), but this one will be a bit less complete for time reasons.

Challenge description

Are you hearing what I’m hearing?

HOST: echoid-7xf5f2sbdofl6.shellweplayaga.me

PORT: 1337

Files:

$ nc echoid-7xf5f2sbdofl6.shellweplayaga.me 1337
Ticket please: ticket{redacted}
Send us your song to be identified
asdf
ERROR: Invalid input size: 1717859169

Source from the organizers: https://github.com/Nautilus-Institute/quals-2025/tree/main/echoid

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Categories: Ctf Security

Tags: Ctf Defcon Dsp Writeup

Reversing and exploiting a program running in an undocumented VM

16 minute read – posted on May 3, 2021 by Zack Orndorff

This weekend, Samurai played the DEF CON CTF Qualifier event. We had a great time playing; much thanks to the organizers for putting on a great event! Many thanks to my teammates, it was awesome playing with you all! One of the challenges this weekend was called baby-a-fallen-lap-ray. It was categorized as a pwn challenge, and it made a comment about being β€˜the return of the parallel machine (or is it?)’.

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Categories: Ctf

Tags: Binary Ninja Ctf Defcon Writeup