ESPILON-CTF-2026-Writeups/Hardware/Glitch_The_Wired
2026-03-22 19:18:58 +01:00
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README.md ESPILON CTF 2026 — Write-ups édition 1 (33 challenges) 2026-03-22 19:18:58 +01:00

Glitch The Wired — Solution

Overview

Simulated voltage glitching attack on a WIRED-MED secure boot module. The goal is to inject a fault during the signature verification phase to bypass it and access the debug console.

Steps

  1. Connect to the glitch lab:
nc <host> 3700
  1. Observe the boot sequence:
observe

Note the cycle ranges — SIG_VERIFY runs at cycles 3200-3400.

  1. Configure glitch parameters:
set_delay 3300
set_width 20

The delay targets the middle of the SIG_VERIFY window. Width of 10-30 cycles works.

  1. Arm and trigger:
arm
trigger

If successful, the boot log shows "SIG_VERIFY ....... SKIPPED" and a debug shell activates.

  1. Read the debug console:
read_console

The flag is in the maintenance token output.

Key Concepts

  • Voltage glitching: Briefly disrupting power supply to cause CPU instruction skips
  • Secure boot bypass: Skipping signature verification allows unsigned code to run
  • Timing precision: The glitch must overlap with the target operation's execution window
  • Width matters: Too short = transient recovery, too wide = brown-out crash