jtagprobe

jtagprobe is a skill for Claude Code, Codex from BrownFineSecurity/iothackbot. It costs 85 tokens per session (1,530 once invoked), scanned A, original, MIT.

A hardware-testing tool that checks whether an embedded device's SWD or JTAG debug port is exposed through a SEGGER J-Link. It classifies the target as OPEN, LOCKED, or DEAD based on the access it allows.

In plain words
What is it for?
Use it to identify the chip, test debug access, determine whether the CPU can be halted and memory read, and assess the device's debug-port security.
Why use it?
It reveals whether production hardware still permits debugging or memory access, including cases where readout protection is only partly enabled.

Skill for Claude CodeCodex

Part of the iothackbot plugin — 13 skills shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/brownfinesecurity/iothackbot/jtagprobe
Any agent
npx skills add BrownFineSecurity/iothackbot --skill jtagprobe
Clone the repo
git clone --depth 1 https://github.com/BrownFineSecurity/iothackbot

Made for: Claude Code, Codex.

Or install iothackbot, the plugin that ships this one along with the rest of its 13 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for jtagprobe

README.md
[![agentmods](https://agentmods.dev/badge/skills/brownfinesecurity/iothackbot/jtagprobe.svg)](https://agentmods.dev/skills/brownfinesecurity/iothackbot/jtagprobe)
Your own site
<a href="https://agentmods.dev/skills/brownfinesecurity/iothackbot/jtagprobe"><img src="https://agentmods.dev/badge/skills/brownfinesecurity/iothackbot/jtagprobe.svg" alt="Measured on agentmods" height="20"></a>
Per session 85 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,530 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00085 $0.01530
Opus 5 $0.00043 $0.00765
Sonnet 5 $0.00017 $0.00306
Haiku 4.5 $0.00009 $0.00153

Measured 5d ago against content hash 0b3e9681261a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

jtagprobe scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/jtagprobe/SKILL.md · 136 lines

How it starts

The opening of the file, as written. The whole thing — 136 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Jtagprobe — SWD/JTAG Debug Interface Tester

You are helping the user determine whether a target's on-chip debug interface is exposed via SWD or JTAG, using the jtagprobe tool. This drives a SEGGER J-Link physically wired to the target.

What the tool tests

Three nested access layers are checked, and the target is classified into one of:

  • OPEN — DP responds, CPU halts, memory reads return plausible data. Full debugger control. Critical finding.
  • LOCKED — DP/IDCODE accessible but memory reads fail or return readout-protection sentinels (0xFFFFFFFF). Indicates STM32 RDP, NXP CRP, Nordic APPROTECT, etc. are engaged. Still a finding — the port should not respond at all in production.
  • DEAD — No DP/IDCODE response on any tested interface/speed. Debug fused off, pins not wired, or wrong target.

Prerequisites

  • A SEGGER J-Link (any variant) connected via USB
  • JLinkExe on PATH — verify with which JLinkExe. If it is installed but not on PATH, point the tool at it with --jlink-binary /path/to/JLinkExe instead of relying on PATH.
  • Target wired to the J-Link 20-pin (or 10-pin Cortex Debug) header. Confirm SWDIO/SWCLK or TDI/TDO/TMS/TCK identification before energizing the target.

If JLinkExe cannot be found at all, tell the user to install SEGGER J-Link software from segger.com. Do not attempt to install it without explicit approval.

Basic usage

Default — sweep SWD then JTAG at 4000/1000/100 kHz, halt, read memory, classify:

jtagprobe

Save per-attempt JLinkExe logs as evidence (recommended for pentest writeups):

jtagprobe --evidence-dir ./evidence/jtagprobe-$(date +%Y%m%d-%H%M%S)

JSON for chaining:

jtagprobe --format json

Common workflows

1. Unknown target, unknown protocol

Just run with defaults. The tool will:

  1. Try SWD at 4 MHz → 1 MHz → 100 kHz
  2. Fall back to JTAG with the same speed sweep
  3. Run a JTAG chain auto-scan as last resort
  4. Identify vendor from DPIDR/IDCODE JEP106 designer field
  5. Halt CPU and read memory to confirm access level

Read the full file on GitHub · 136 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 136 lines · 85 tokens per session scan A 0b3e9681261a

Subscribe to this mod's changes

jtagprobe is a skill published in the GitHub repository BrownFineSecurity/iothackbot (828 stars, last pushed 3mo ago), licensed MIT. It adds 85 tokens to every session and 1,530 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

integrated-browser

Use this when working on the VS Code integrated browser ("browserView") to understand its architecture and mental model. Covers the embedded Chromium browser, its editor tab, navigation, overlay/layout, sessions, and agent browser tools under src/vs/platform/browserView and src/vs/workbench/contrib/browserView.

microsoft/vscode · 68 tokens

gke-compute-classes

Configures, optimizes, and troubleshoots GKE ComputeClasses. Use when configuring Spot VMs with on-demand fallback, targeting specific accelerators (GPUs/TPUs) or machine families, restricting ComputeClass access, or debugging pending pods related to node pool auto-creation. Do not use for cluster-level Node Auto…

google/skills · 83 tokens

jetson-diagnostic

Read-only Jetson health snapshot for identity, memory, GPU, thermal, power, storage, services, and top processes.

NVIDIA/skills · 30 tokens

doca-socket-relay

Use this skill when the operator is driving the DOCA Socket Relay to bridge a socket-oriented host application onto a BlueField DPU peer without rewriting it — picking the deployment shape (in-process, sidecar, or BlueField service container), configuring the host-side socket and the DPU-side forwarding endpoint…

NVIDIA/skills · 236 tokens

offensive-z-wave

Z-Wave attack methodology — sniffing with Z-Force / EZ-Wave / RTL-SDR + ZniffMobile, S0 (legacy) network-key derivation flaw and key reuse, S2 (modern) ECDH commissioning analysis, replay/injection on unauthenticated nodes, default-key brute-force on test deployments, and home-automation hub pivots. Use when targeting…

SnailSploit/Claude-Red · 113 tokens

hsb-flash

Flash the FPGA on an HSB board connected to an NVIDIA devkit. Supports HSB Lattice boards (FPGA versions 2407, 2412, 2507, 2510) and Leopard Imaging VB1940 "all-in-one" cameras (FPGA versions 2507, 2510). Uses release-specific YAML manifests and board-type-specific program commands. Lattice and VB1940 commands must…

NVIDIA/skills · 94 tokens