offensive-shellcode SKILL.md skillA

offensive-shellcode from miosa-osa/osa is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.

Install it, pinned

mdr add miosa-osa/osa/offensive-shellcode@git:20260913.e13b6b8

Pins git:20260913.e13b6b8 in mdr.lock. Pin the fingerprint instead.

Audit grade: A, 17 of 17 checks passed
Kind: SKILL.md skill
Repository: miosa-osa/osa
Path: priv/skills/offensive-shellcode/SKILL.md
Versions recorded: 1
Latest version: git:20260913.e13b6b8, committed Sep 13, 2026
Size: 20,025 bytes
Repository stars: 78
License: Apache-2.0

Shellcode development reference for offensive security engagements. Use when writing custom x86/x64 shellcode, implementing position-independent code (PIC), building shellcode loaders, evading AV/EDR detection, or converting PE files to shellcode. Covers null byte avoidance, API hashing, encoder/decoder patterns, staged vs stageless payloads, Windows PEB traversal, and cross-platform shellcode techniques.

Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.

What the file says

## Shellcode Development Workflow

1. Define concept and target platform (x86/x64, Windows/Linux/macOS)
2. Write assembly using position-independent techniques
3. Extract binary and test in controlled environment
4. Apply null byte avoidance and optimizations
5. Encode/encrypt to evade static detection
6. Package with loader and choose delivery method

---

## Basic Concepts

### Execution Pattern (Allocate-Write-Execute)

Avoid direct `PAGE_EXECUTE_READWRITE` — prefer:
1. Allocate with `PAGE_READWRITE`
2. Write shellcode to allocated region
3. Call `VirtualProtect` to switch to `PAGE_EXECUTE_READ`

```c
char *dest = VirtualAlloc(NULL, 0x1234, MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE);
memcpy(dest, shellcode, 0x1234);
VirtualProtect(dest, 0x1234, PAGE_EXECUTE_READ, &old);
((void(*)())dest)();
```

### Position-Independent Code (PIC) Techniques

| Method | Platform | Notes |
|--------|----------|-------|
| Call/Pop | Windows | Push next addr, pop into register |
| FPU state | Windows | `fstenv` saves instruction pointer |
| SEH | Windows | Exception handler stores EIP |
| GOT | Linux | Global Offset Table |
| VDSO | Linux | Kernel-provided shared object |

---
…

Read the whole file at its exact version.

How to install

The exact contents, by fingerprint

mdr add miosa-osa/osa/offensive-shellcode@sha256:d41fd761f24c219d

The line at the top of this page pins the label git:20260913.e13b6b8, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.

Badge

[![mdr](https://markdownregistry.com/badge/art_uyhabttouyotg7lq.svg)](https://markdownregistry.com/a/art_uyhabttouyotg7lq)

6 badge image fetches in 30 days. What the badge shows.

Versions

The registry has recorded 1 version of this file, committed on Sep 13, 2026.

version	committed	commit	size	audit
git:20260913.e13b6b8 latest	2026-09-13	e13b6b8	20,025 B	A	view

Audit of the latest version

A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.

pass: Frontmatter block present
pass: Frontmatter declares a name
pass: Frontmatter declares a description
pass: Size between 200 bytes and 200 KB (20025 bytes)
pass: No zero-width or bidi control characters
pass: No instruction hidden inside an HTML comment
pass: No link to an exfiltration or paste host
pass: No credential-shaped string
pass: No instruction to send local credentials anywhere
pass: No text hidden with inline styles
pass: No prompt-injection phrasing
pass: No curl or wget piped into a shell
pass: No recursive delete of root, home or parent
pass: No instruction to read or print local credentials
pass: No base64 blob over 200 characters
pass: No link to a raw IP address
pass: No script tag

Source

GitHub

miosa-osa/osa · 78 stars · license Apache-2.0 · pushed 2026-10-29 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_uyhabttouyotg7lq
GET https://markdownregistry.com/api/v1/resolve?ref=miosa-osa/osa/offensive-shellcode
GET https://markdownregistry.com/api/v1/blob/d41fd761f24c219d2aa3a87f479c5dfff8b866561cb2c99a3643c504c72ef2d6

Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.

Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.

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