# Arb Injection

> BYOCB ArbInjectionSkill: Scan EVM smart contracts for arbitrary call injection vulnerabilities. Monitor chains in real-time or scan specific addresses.

- Skill: `bringyourownbot/arb-injection` (Agent Skill, multi-file: 7 files)
- Install (CLI): `npx skillmds@latest add bringyourownbot/arb-injection`
- Raw SKILL.md: https://api.skillmd.com/api/skills/bringyourownbot/arb-injection/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: BringYourOwnBot (https://skillmd.com/u/bringyourownbot)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/bringyourownbot/arb-injection

---


# BYOCB ArbInjectionSkill

> ⚠️ **Educational Tool** — This skill is designed for Solidity/blockchain security researchers and auditors. Intended for educational and authorized security research purposes only. Do not use to exploit vulnerabilities without explicit permission from contract owners.

Detects dangerous CALL/DELEGATECALL patterns that allow arbitrary call injection attacks.

## How It Works

ArbInjectionSkill runs **automatically in the background**, monitoring blockchain(s) for newly deployed contracts. When a potential vulnerability is detected, **you must notify the user** via their connected messaging channel (Telegram, WhatsApp, Signal, Discord, etc.).

## Install

```bash
npm install -g byocb-arb-injection
```

This installs the `arb-injection` CLI globally.

## Running the Monitor

Start as a **background session** for continuous monitoring:

```bash
arb-injection monitor <chain> [--no-llm] [--output <dir>]
```

Chains: `eth`, `bsc`, `base`, `arb`, `op`, `polygon`, `hyper`

The monitor will:
1. Subscribe to new blocks
2. Detect contract deployments
3. Scan bytecode for vulnerabilities
4. Save findings to `./results/` (or custom `--output` dir)

## Alerting Users

**Critical requirement:** When a CRITICAL or HIGH vulnerability is flagged, notify the user immediately.

Check for new findings periodically (via heartbeat or cron):

```bash
# Find findings from last 30 minutes (Linux/Mac)
find ./results -name "*.md" -mmin -30

# Windows PowerShell
Get-ChildItem ./results -Filter *.md | Where-Object { $_.LastWriteTime -gt (Get-Date).AddMinutes(-30) }
```

When new findings exist with verdict CRITICAL or HIGH:
1. Read the `.md` report
2. Verify it's not a known false positive (see below)
3. Send alert via `message` tool to user's preferred channel

Example alert:
```
🚨 ArbInjection Alert: Potential vulnerability detected

Chain: BSC
Contract: 0x1234...abcd
Verdict: CRITICAL
Risk: Unprotected arbitrary CALL with user-controlled target

[Link to explorer]
```

## Manual Scan

Scan a specific contract on-demand:

```bash
arb-injection scan <address> --chain <chain>
arb-injection scan ./bytecode.txt  # Local bytecode file
```

## Interpreting Results

| Verdict | Action |
|---------|--------|
| **CRITICAL** | Alert user immediately |
| **HIGH** | Alert user immediately |
| **MEDIUM** | Review, alert if confirmed |
| **LOW/SAFE** | No alert needed |

Results saved to `./results/` as `.json` and `.md` files.

## False Positives

**Do NOT alert** for these patterns (safe by design):
- Immutable DELEGATECALL targets (hardcoded address in bytecode)
- EIP-1167 minimal proxies (clone pattern)
- EIP-1967 storage proxies (upgradeable pattern with admin protection)
- UUPS/Transparent proxies with access control
- DEX callbacks (uniswapV3SwapCallback, etc.)
- Known safe contracts: Multicall3, 1inch, Uniswap, Permit2

**Verify before alerting:** Check if the flagged CALL target is:
- Hardcoded (immutable) → FALSE POSITIVE
- From calldata/user input → REAL VULNERABILITY

## Environment

Optional environment variables:
```
ANTHROPIC_API_KEY=sk-ant-...   # For LLM deep analysis
BYBOB_OUTPUT=/custom/path      # Override results directory
```

## Updates

Update to latest version:
```bash
npm update -g byocb-arb-injection
```

Schedule weekly update check (Sundays 09:00):
```json
{
  "schedule": { "kind": "cron", "expr": "0 9 * * 0" },
  "payload": { "kind": "systemEvent", "text": "ArbInjectionSkill weekly update: npm update -g byocb-arb-injection" },
  "sessionTarget": "main"
}
```

## Source

npm: https://www.npmjs.com/package/byocb-arb-injection  
GitHub: https://github.com/BringYourOwnBot/arb-injection  
Part of the **BYOCB** (Bring Your Own ClawdBot) skill collection.