coding-mastery

A software-engineering guide for building security tools, automation, network programs, cryptographic code, and performance-sensitive systems.

In plain words
What is it for?
Exploit prototypes, penetration-testing automation, network protocols, security analysis tools, cryptography work, and systems programming.
Why use it?
It provides language and library direction for technically demanding programming tasks.

Skill for Claude CodeCodex

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/jessefmoore/offensive-claude-code/coding-mastery
Any agent
npx skills add jessefmoore/offensive-claude-code --skill coding-mastery
Clone the repo
git clone --depth 1 https://github.com/jessefmoore/offensive-claude-code

Made for: Claude Code, Codex.

Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,420 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 $0.00024 $0.01420
Opus 5 $0.00012 $0.00710
Sonnet 5 $0.00005 $0.00284
Haiku 4.5 $0.00002 $0.00142

Measured 2d ago against content hash 4d4d0205d4eb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

coding-mastery 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 2d 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/coding-mastery/SKILL.md · 230 lines

How it starts

The opening of the file, as written. The whole thing — 230 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Coding Mastery

When to Activate

  • Writing exploit code, PoCs, or security tools
  • Developing automation scripts for pentesting workflows
  • Implementing network protocols or custom C2
  • Building security analysis tools
  • Cryptographic implementation or analysis
  • Performance-critical systems programming

Languages & Use Cases

Python (Primary — Offensive Tooling)

# Exploit development with pwntools
from pwn import *
context(arch='amd64', os='linux')

# Network programming
import socket, ssl, struct
import asyncio, aiohttp  # async operations

# Web exploitation
import requests, urllib3
from bs4 import BeautifulSoup

# Crypto
from Crypto.Cipher import AES, DES
from Crypto.PublicKey import RSA
import hashlib, hmac

# Binary analysis
import struct, ctypes
from capstone import *  # disassembly
from unicorn import *   # emulation
from keystone import *  # assembly

C/C++ (Systems & Exploit Dev)

// Shellcode development
// Position-independent code, null-free
// Syscall-based (avoid libc dependency)

// Kernel module development
#include <linux/module.h>
#include <linux/kernel.h>

// Windows API abuse
#include <windows.h>
#include <winternl.h>
// Direct syscalls, NTAPI

// Memory manipulation
// Custom allocators, heap spray, ROP gadget finders

Go (Offensive Tooling & C2)

// Implant development (cross-compile, static binary)
// C2 communication (HTTP/DNS/named pipes)
// Network scanning and enumeration
// Proxy/tunnel tools (chisel-like)

// Advantages: single binary, cross-platform, fast, good crypto stdlib

Rust (High-Performance Security Tools)

// Memory-safe exploit tooling
// High-performance scanners
// Custom protocol implementations
// Fuzzing harnesses

PowerShell (Windows Post-Exploitation)

# AMSI bypass, ETW patching
# In-memory execution (reflection)
# AD enumeration and exploitation
# Fileless malware techniques

Assembly (x86/x64/ARM)

; Shellcode
; ROP gadgets
; Anti-debugging
; Kernel exploitation
; Architecture-specific tricks

Read the full file on GitHub · 230 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. 2d ago First seen · 230 lines · 24 tokens per session scan A 4d4d0205d4eb

Subscribe to this mod's changes

coding-mastery is a skill published in the GitHub repository jessefmoore/offensive-claude-code (2 stars, last pushed 3mo ago), licensed MIT. It adds 24 tokens to every session and 1,420 once invoked, about $0.0001 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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