building-config-extractors

building-config-extractors is a skill for Claude Code, Codex from meltedinhex/analyst-ai-pack. It costs 66 tokens per session (714 once invoked), scanned A, original, Apache-2.0.

A reusable malware-configuration extractor driven by a JSON description of where data is stored, how it is decoded, and which fields to read.

In plain words
What is it for?
Use it to locate an embedded configuration, apply steps such as XOR or Base64 decoding, extract strings, numbers, IP addresses, and other fields, and validate the results.
Why use it?
It replaces one-off parsing scripts and produces consistent, defanged results across samples from the same malware family, provided the format has been correctly reversed.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to locate an embedded configuration, apply steps such as XOR or Base64 decoding, extract strings, numbers, IP addresses, and other fields, and validate the results.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/meltedinhex/analyst-ai-pack/building-config-extractors
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 meltedinhex/analyst-ai-pack --skill building-config-extractors
Clone the repo
git clone --depth 1 https://github.com/meltedinhex/analyst-ai-pack

Made for: Claude Code, Codex.

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 building-config-extractors

README.md
[![agentmods](https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/building-config-extractors/github.svg)](https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/building-config-extractors)
Your own site
<a href="https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/building-config-extractors"><img src="https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/building-config-extractors/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 building-config-extractors

Your own site · 80×15
<a href="https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/building-config-extractors"><img src="https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/building-config-extractors.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 66 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 714 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00066 $0.00714
Opus 5 $0.00033 $0.00357
Sonnet 5 $0.00013 $0.00143
Haiku 4.5 $0.00007 $0.00071

Measured 10d ago against content hash 7d0be17eaef6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

building-config-extractors 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 10d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/analyst.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/building-config-extractors/SKILL.md · 90 lines

What it actually says

Building Config Extractors

When to Use

  • You have reversed a family's config format and want a reusable, declarative extractor instead of one-off scripts.
  • You need to apply a spec (offset, XOR/base64 layers, field map) to many samples and emit structured, defanged config.

Do not use a spec built for one variant blindly on another — re-verify offsets/keys per variant. This skill reads samples statically and executes nothing.

Prerequisites

  • A reversed understanding of the config (location, decode layers, fields) expressed as a JSON spec.

Safety & Handling

  • Read bytes statically; defang recovered endpoints in output.

Workflow

Step 1: Write the extraction spec

Define a JSON spec: blob offset/length (or a marker to search), ordered decode layers (xor with key, base64), and fields (name, offset, length, type: str/u16/u32/ipv4).

Step 2: Run the extractor

python scripts/analyst.py extract sample.bin --spec family.json

Locates the blob, applies decode layers, parses fields, and defangs URL/IP fields.

Step 3: Validate output

Confirm fields are plausible (valid hosts, ports, IDs); adjust the spec as needed.

Step 4: Reuse

Store the spec per family and apply across the corpus.

Validation

  • The spec round-trips on a known sample to the expected config.
  • Decode layers are applied in order and produce readable output.
  • URL/IP fields are defanged in the emitted config.

Pitfalls

  • Hardcoding a variant-specific offset that shifts in other builds — prefer markers.
  • Wrong field endianness (u16/u32 little vs big) producing garbage ports.
  • Forgetting a decode layer (base64 over XOR) and parsing ciphertext as fields.

References

  • See references/api-reference.md for the extractor engine.
  • ATT&CK T1140 and config-extractor framework concepts (linked in frontmatter).
Files

What ships with it

3 files 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. 10d ago First seen · 90 lines · 66 tokens per session scan A 7d0be17eaef6

Subscribe to this mod's changes

building-config-extractors is a skill published in the GitHub repository meltedinhex/analyst-ai-pack (22 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 66 tokens to every session and 714 once invoked, about $0.0003 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 2026-08-30.

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