exploiting-web3-smart-contracts

exploiting-web3-smart-contracts is a skill for Claude Code from trilwu/secskills. It costs 47 tokens per session (2,925 once invoked), scanned B, original, MIT.

A security-testing guide for blockchain applications and smart contracts, which are programs that run on a blockchain. It covers issues such as reentrancy, arithmetic errors, broken access controls, and DeFi-specific flaws.

In plain words
What is it for?
Use it to audit smart contracts, DeFi protocols, NFT platforms, and other Web3 applications in a local blockchain fork or test environment.
Why use it?
It helps find bugs that could let someone alter contract behavior, bypass permissions, or put digital assets at risk.

Skill for Claude Code

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

Part of the secskills-offense plugin — 40 skills shipped together

Good fit Use it to audit smart contracts, DeFi protocols, NFT platforms, and other Web3 applications in a local blockchain fork or test environment.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/trilwu/secskills/exploiting-web3-smart-contracts
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 trilwu/secskills --skill exploiting-web3-smart-contracts
Clone the repo
git clone --depth 1 https://github.com/trilwu/secskills

Made for: Claude Code.

Or install secskills-offense, the plugin that ships this one along with the rest of its 40 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 exploiting-web3-smart-contracts

README.md
[![agentmods](https://agentmods.dev/badge/skills/trilwu/secskills/exploiting-web3-smart-contracts/github.svg)](https://agentmods.dev/skills/trilwu/secskills/exploiting-web3-smart-contracts)
Your own site
<a href="https://agentmods.dev/skills/trilwu/secskills/exploiting-web3-smart-contracts"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/exploiting-web3-smart-contracts/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 exploiting-web3-smart-contracts

Your own site · 80×15
<a href="https://agentmods.dev/skills/trilwu/secskills/exploiting-web3-smart-contracts"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/exploiting-web3-smart-contracts.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,925 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 3 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 8 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Tool Misuse · line 59
    Tool calls are chained to bypass individual safety checks or escalate capabilities beyond what any single tool call would allow.
    Fix: Limit tool chaining depth and validate the output of each tool before passing it to the next. Require explicit user approval for multi-step chains.
  • high Supply Chain · line 66
    Remote code is downloaded and executed. This bypasses code review and could introduce malicious code.
    Fix: Avoid downloading and executing remote scripts. Use trusted packages from PyPI/npm. If remote fetch is required, verify checksums and use HTTPS.
  • high Tool Misuse · line 66
    Tool calls are chained to bypass individual safety checks or escalate capabilities beyond what any single tool call would allow.
    Fix: Limit tool chaining depth and validate the output of each tool before passing it to the next. Require explicit user approval for multi-step chains.
  • medium Privilege Escalation · line 59
    Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.
    Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
  • medium Privilege Escalation · line 60
    Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.
    Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
  • medium Privilege Escalation · line 59
    Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.
    Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
  • medium Data Exfiltration · line 379
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
  • medium Data Exfiltration · line 382
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
How audits are shown
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 $0.00047 $0.02925
Opus 5 $0.00023 $0.01463
Sonnet 5 $0.00009 $0.00585
Haiku 4.5 $0.00005 $0.00293

Measured 5d ago against content hash d3975b3fd286, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade B, and why

exploiting-web3-smart-contracts scanned grade B with 3 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.

Asks for rootlowPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

curl -fsSL https://deb.nodesource.com/setup_18.x | sudo -E bash -

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Downloads and executes remote codemediumSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

curl -L https://foundry.paradigm.xyz | bash

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -fsSL https://deb.nodesource.com/setup_18.x | sudo -E bash -
secskills-offense/skills/exploiting-web3-smart-contracts/SKILL.md · 474 lines

How it starts

The opening of the file, as written. The whole thing — 474 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Exploiting Web3 and Smart Contracts

When to Use

  • Smart contract security auditing
  • DeFi protocol testing
  • Web3 application pentesting
  • Blockchain vulnerability assessment
  • NFT platform security

Scope and authorization. A deployed mainnet contract is not a test target. It is a live system custodying other people's funds, it is permissionless — so nothing stops you technically — and it is irreversible once you transact. None of that makes exploitation authorized.

  • Fork, never touch mainnet. Prove every finding against a local fork (Anvil, Hardhat, Tenderly) or a testnet deployment. There is no legitimate reason to run a working exploit against a live contract.
  • The law here is unsettled — which is a reason for caution, not comfort. Two headline prosecutions went the exploiter's way: a Paris court acquitted the Platypus Finance pair in December 2023, holding that calling a public smart contract was not unauthorized access and that the emergency-withdrawal manipulation did not meet the fraud standard; and in May 2025 a US judge vacated Avraham Eisenberg's Mango Markets convictions on venue and insufficient evidence of misrepresentation, a ruling prosecutors have appealed. Do not read those as permission. Both turned on jurisdiction- specific facts, the Platypus court expressly left civil liability open, and in every one of these matters the defendant was arrested, had funds seized, and litigated for years before prevailing. Winning eventually is not the same as being authorized.
  • Bug bounty scope is narrow and literal. Immunefi-style programs typically require proof on a fork, forbid mainnet exploitation and live-user impact, and have specific disclosure channels. Read the scope for the specific program before testing, not after.
  • Unaudited ≠ abandoned. An anonymous or inactive deployer does not make a contract ownerless; the depositors are still identifiable victims.

For contracts you do not own, work from source and simulation only, and disclose through the project's published channel or a coordinating platform.

Read the full file on GitHub · 474 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 474 lines · 47 tokens per session scan B d3975b3fd286

Subscribe to this mod's changes

exploiting-web3-smart-contracts is a skill published in the GitHub repository trilwu/secskills (137 stars, last pushed 5d ago), licensed MIT. It adds 47 tokens to every session and 2,925 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 3 findings (asks for root, downloads and executes remote code, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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