anti-debugging-techniques

A reverse-engineering guide for finding and bypassing anti-debugging checks in Linux and Windows programs. Anti-debugging checks try to detect tools used to inspect a running program.

In plain words
What is it for?
Use it when examining protected binaries that check debugger flags, timing, process information, signals, exceptions, or startup callbacks.
Why use it?
These checks can stop a debugger or change a program’s behavior, making analysis harder.

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/miru-zero/zero-brain/anti-debugging-techniques
Any agent
npx skills add miru-zero/zero-brain --skill anti-debugging-techniques
Clone the repo
git clone --depth 1 https://github.com/miru-zero/zero-brain

Made for: Claude Code, Codex.

Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,862 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 94% copy Near-identical to another mod 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 $0.00046 $0.03862
Opus 5 $0.00023 $0.01931
Sonnet 5 $0.00009 $0.00772
Haiku 4.5 $0.00005 $0.00386

Measured yesterday against content hash 4f9af8b9b17d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

anti-debugging-techniques 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 yesterday.

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.

Origin

This is a copy

94% identical to anti-debugging-techniques — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/anti-debugging-techniques/SKILL.md · 406 lines

How it starts

The opening of the file, as written. The whole thing — 406 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Anti-Debugging Techniques — Detection & Bypass Playbook

AI LOAD INSTRUCTION: Expert anti-debug techniques across Linux and Windows. Covers ptrace, PEB flags, NtQueryInformationProcess, timing attacks, signal-based detection, TLS callbacks, VEH tricks, and all corresponding bypass methods. Base models often miss the distinction between user-mode and kernel-mode detection and the correct patching strategy for each.

Advanced Reference

Also load ANTI_DEBUG_MATRIX.md when you need:

  • Complete cross-reference matrix of technique × OS × detection method × bypass method
  • Per-technique reliability ratings and false-positive notes
  • Tool compatibility chart (GDB, x64dbg, WinDbg, Frida, ScyllaHide)

Quick bypass picks

Detection Class First Bypass Backup
ptrace-based (Linux) LD_PRELOAD hook ptrace() → return 0 Kernel module to hide tracer
PEB.BeingDebugged (Windows) Patch PEB byte at fs:[0x30]+0x2 ScyllaHide auto-patch
Timing check (rdtsc) Conditional BP after rdtsc, fix registers Frida hook rdtsc return
IsDebuggerPresent NOP the call / hook return 0 x64dbg built-in hide
INT 2D / UD2 exception Set VEH to handle gracefully TitanHide driver

1. LINUX ANTI-DEBUG TECHNIQUES

1.1 ptrace(PTRACE_TRACEME)

The classic self-attach: a process calls ptrace(PTRACE_TRACEME, 0, 0, 0). If a debugger is already attached, the call fails (returns -1).

if (ptrace(PTRACE_TRACEME, 0, 0, 0) == -1) {
    exit(1); // debugger detected
}

Read the full file on GitHub · 406 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. yesterday First seen · 406 lines · 46 tokens per session scan A 4f9af8b9b17d

Subscribe to this mod's changes

anti-debugging-techniques is a skill published in the GitHub repository miru-zero/zero-brain (0 stars, last pushed 14d ago), licensed MIT. It adds 46 tokens to every session and 3,862 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to anti-debugging-techniques, differing in 6 lines, and is treated as a copy.

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