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.
npx skills add UnboundCompute/security-agent-skills --skill hunting-signature-replay-and-eip712-domain-trustgit clone --depth 1 https://github.com/UnboundCompute/security-agent-skillsWrote 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.
[](https://agentmods.dev/skills/unboundcompute/security-agent-skills/hunting-signature-replay-and-eip712-domain-trust)<a href="https://agentmods.dev/skills/unboundcompute/security-agent-skills/hunting-signature-replay-and-eip712-domain-trust"><img src="https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/hunting-signature-replay-and-eip712-domain-trust/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.
<a href="https://agentmods.dev/skills/unboundcompute/security-agent-skills/hunting-signature-replay-and-eip712-domain-trust"><img src="https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/hunting-signature-replay-and-eip712-domain-trust.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00205 | $0.02171 |
| Opus 5.5 | $0.00082 | $0.00868 |
| Sonnet 5.5 | $0.00041 | $0.00434 |
| Haiku 4.5 | $0.00020 | $0.00217 |
Grade A, and why
hunting-signature-replay-and-eip712-domain-trust 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 1mo 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.
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.
Hunting signature replay and EIP-712 domain trust: a signature authorizes one action, once, here
A signature is an authorization, and an authorization has to be bound to exactly what it authorizes: one action, on one chain, at one contract, used once. When any part of that binding is missing, the same signature authorizes more than the signer intended. EIP-712 exists to make the binding explicit, the domain separator carries the chain id and the verifying contract, and the typed data carries the action's fields, but a contract only gets the protection it actually checks. A signature with no nonce can be submitted again, so a permit or meta-transaction replays. A domain separator missing the chain id or the verifying contract lets a signature valid on one chain or one deployment be replayed on another. Signed fields that omit something the action depends on, an amount, a recipient, a deadline, let a different action reuse the same signature. And signer recovery that accepts a malleable signature or an unchecked zero address lets a forged or duplicated signature through. The hunt is to find where a signed message is verified and check whether its binding is complete. You hunt this by taking a valid signature and trying to use it twice, elsewhere, or for something else.
When to use
- A signed message (an EIP-712 permit, a meta-transaction, an off-chain order) authorizes an on-chain or backend action.
- The signature may lack a nonce, or its domain separator may omit the chain id or verifying contract.
- Signer recovery may accept a malleable signature or an unchecked zero address, or the signed fields may omit part of the action.
Scope check
Test signature replay only against contracts and services you own or are authorized to assess, on testnets or a local fork. Replaying a signature executes a real authorized action, so use test keys and deployments and never replay a signature that moves real value or acts for someone else. If you can't name the authorization, stop.
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.
- 1mo ago First seen · 138 lines · 205 tokens per session scan A 32ee71a51a9f
hunting-signature-replay-and-eip712-domain-trust is a skill published in the GitHub repository UnboundCompute/security-agent-skills (5 stars, last pushed 1mo ago), licensed MIT. It adds 205 tokens to every session and 2,171 once invoked, about $0.0008 per session on Opus 5.5. 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 2026-09-05.
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