analyzing-ransomware-encryption-behavior

analyzing-ransomware-encryption-behavior is a skill for Claude Code, Codex from meltedinhex/analyst-ai-pack. It costs 72 tokens per session (898 once invoked), scanned A, original, Apache-2.0.

A static-analysis guide for understanding how ransomware encrypts files and leaves signs of its activity. Ransomware is malware that blocks access to files, usually to demand payment.

In plain words
What is it for?
Use it to study encryption code, key handling, file extensions or markers, deleted shadow copies, and ransom notes in an isolated lab using disposable files.
Why use it?
It helps determine what encryption approach was used, which files were targeted, and whether recovery without the key may be possible. It also documents evidence for incident-response work.

Skill for Claude CodeCodex

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

Good fit Use it to study encryption code, key handling, file extensions or markers, deleted shadow copies, and ransom notes in an isolated lab using disposable files.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/meltedinhex/analyst-ai-pack/analyzing-ransomware-encryption-behavior
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 analyzing-ransomware-encryption-behavior
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 analyzing-ransomware-encryption-behavior

README.md
[![agentmods](https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/analyzing-ransomware-encryption-behavior.svg)](https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/analyzing-ransomware-encryption-behavior)
Your own site
<a href="https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/analyzing-ransomware-encryption-behavior"><img src="https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/analyzing-ransomware-encryption-behavior.svg" alt="Measured on agentmods" height="20"></a>
Per session 72 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 898 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 $0.00072 $0.00898
Opus 5 $0.00036 $0.00449
Sonnet 5 $0.00014 $0.00180
Haiku 4.5 $0.00007 $0.00090

Measured 8d ago against content hash ec84fd6c29df, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

analyzing-ransomware-encryption-behavior 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 8d 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/analyzing-ransomware-encryption-behavior/SKILL.md · 114 lines

How it starts

The opening of the file, as written. The whole thing — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Analyzing Ransomware Encryption Behavior

When to Use

  • You need to understand how a ransomware sample encrypts data and whether recovery without the key is feasible.
  • You are documenting file targeting, markers, and the ransom workflow for an IR report.
  • You want to identify the crypto primitives to assess decryptability and detection points.

Do not use this to attempt key recovery on production data without backups; analyze in the lab on disposable test files only.

Prerequisites

  • Isolated lab with disposable test files of varied types/sizes.
  • Static/RE tools (see the Ghidra and crypto-identification skills) and the dynamic-analysis setup.
  • A clean snapshot to revert.

Safety & Handling

  • Detonate only against throwaway files in the isolated victim VM; never real data.
  • Treat the sample and any dropped components as live; revert after each run.

Workflow

Step 1: Identify the crypto scheme statically

Locate crypto constants and APIs to classify the scheme:

Symmetric only (AES/ChaCha/RC4)  -> key may be derivable/recoverable if mishandled
Asymmetric (RSA/ECC) wrapping    -> per-file symmetric key wrapped with attacker pubkey
Hybrid (typical)                 -> AES per file, RSA-wrapped key in the encrypted file/footer

Look for AES S-boxes, ChaCha constants ("expand 32-byte k"), and CryptImportKey/BCrypt*.

Step 2: Trace key generation and handling

Determine where the symmetric key comes from (CSPRNG vs weak source), whether it is stored, and how it is protected. Weak/reused keys or keys left in memory are recovery opportunities.

Step 3: Map file targeting

Identify which directories/extensions are targeted or skipped (allowlist of system paths), size thresholds, and partial-vs-full encryption (many encrypt only the first N bytes/blocks for speed).

Step 4: Capture markers and metadata

Most families append an extension, write a per-file footer/magic marker, and store the wrapped key or IV there. The script fingerprints before/after test files to extract markers.

Read the full file on GitHub · 114 lines

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. 8d ago First seen · 114 lines · 72 tokens per session scan A ec84fd6c29df

Subscribe to this mod's changes

analyzing-ransomware-encryption-behavior is a skill published in the GitHub repository meltedinhex/analyst-ai-pack (22 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 72 tokens to every session and 898 once invoked, about $0.0004 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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