auditing-secure-boot-and-firmware-signing

auditing-secure-boot-and-firmware-signing is a skill for Claude Code from UnboundCompute/security-agent-skills. It costs 184 tokens per session (2,175 once invoked), scanned A, original, MIT.

A method for checking firmware updates and bootloaders, the software that starts a device, for missing signature checks. It traces whether an image is authenticated before it is written to device storage or started.

In plain words
What is it for?
Auditing embedded update and startup code, especially the path from receiving a firmware image to writing it or booting it.
Why use it?
It finds paths that could allow tampered, unsigned, or older vulnerable firmware to be installed or run.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the security-agent-skills plugin — 194 skills shipped together

Good fit Auditing embedded update and startup code, especially the path from receiving a firmware image to writing it or booting it.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/unboundcompute/security-agent-skills/auditing-secure-boot-and-firmware-signing
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.

Any agent
npx skills add UnboundCompute/security-agent-skills --skill auditing-secure-boot-and-firmware-signing
Clone the repo
git clone --depth 1 https://github.com/UnboundCompute/security-agent-skills

Made for: Claude Code.

Or install security-agent-skills, the plugin that ships this one along with the rest of its 194 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 auditing-secure-boot-and-firmware-signing

README.md
[![agentmods](https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/auditing-secure-boot-and-firmware-signing/github.svg)](https://agentmods.dev/skills/unboundcompute/security-agent-skills/auditing-secure-boot-and-firmware-signing)
Your own site
<a href="https://agentmods.dev/skills/unboundcompute/security-agent-skills/auditing-secure-boot-and-firmware-signing"><img src="https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/auditing-secure-boot-and-firmware-signing/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for auditing-secure-boot-and-firmware-signing

Your own site · 80×15
<a href="https://agentmods.dev/skills/unboundcompute/security-agent-skills/auditing-secure-boot-and-firmware-signing"><img src="https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/auditing-secure-boot-and-firmware-signing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 184 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,175 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00184 $0.02175
Opus 5 $0.00092 $0.01087
Sonnet 5 $0.00037 $0.00435
Haiku 4.5 $0.00018 $0.00217

Measured 12d ago against content hash 2e9b903a13c3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

auditing-secure-boot-and-firmware-signing 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 12d 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/auditing-secure-boot-and-firmware-signing/SKILL.md · 138 lines

How it starts

The opening of the file, as written. The whole thing — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Auditing secure boot and firmware signing: does a verified signature gate every path to flash and boot

Firmware is the most durable place an attacker can land, and the whole defense is one property: an image is verified for authenticity before any code writes it to a boot slot or jumps to it. Auditing that property is a domination question, not a checklist. Trace the received image to every place it is committed, to flash or to the program counter, and ask whether a correct, enforced signature check stands on every path, over the exact bytes that reach the commit, against a key the attacker cannot influence. The common failures are all ways that check is absent, thrown away, checking the wrong thing, or checking the wrong bytes. You find them by reading the receipt-to-commit path, not by trusting that a function named verify verifies.

When to use

  • Code receives a firmware image over an update channel and writes it to flash or activates a boot slot.
  • A bootloader decides whether to execute an image at startup.
  • You want to know whether an unsigned, tampered, or downgraded image can be flashed or booted.

Scope check

Audit firmware trust boundaries only on devices and code you own or are authorized to assess, and flash crafted images only to hardware in scope. A confirmed secure-boot bypass is persistent code execution, so treat it accordingly and coordinate. If you can't name the authorization, stop.

The loop

  1. Map the receipt-to-commit paths. Find where an image arrives (an update channel, a port, a shared store) and every sink that commits it: a flash erase or write of a boot region, a call that marks a slot active or valid, and the branch to the image's entry point at boot. These sinks are what a verification must dominate, so enumerate them before judging any check.

  2. Check that verification exists and its result is enforced. On each path, a signature check must run between receipt and commit. The bug is a commit with no check, a result computed and then discarded, a result defaulted to success and only set to failure on one branch, or an inverted test. A verify whose outcome does not gate the flash or the boot is not a check.

Read the full file on GitHub · 138 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. 12d ago First seen · 138 lines · 184 tokens per session scan A 2e9b903a13c3

Subscribe to this mod's changes

auditing-secure-boot-and-firmware-signing is a skill published in the GitHub repository UnboundCompute/security-agent-skills (5 stars, last pushed 3d ago), licensed MIT. It adds 184 tokens to every session and 2,175 once invoked, about $0.0009 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 2026-08-31.

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