analyzing-malicious-pdfs

analyzing-malicious-pdfs is a skill for Claude Code, Codex from meltedinhex/analyst-ai-pack. It costs 73 tokens per session (762 once invoked), scanned A, original, Apache-2.0.

A safe inspection workflow for suspicious PDF files that looks at their internal structure without opening them in a document viewer. It searches for scripts, automatic actions, embedded files, links, and suspicious encoded data.

In plain words
What is it for?
Use it to investigate phishing attachments, find PDF JavaScript or automatic launch actions, and extract suspicious embedded content for analysis.
Why use it?
A malicious PDF can run unsafe actions when opened. Static inspection helps reveal those risks while avoiding the potential danger of launching the file normally.

Skill for Claude CodeCodex

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

Good fit Use it to investigate phishing attachments, find PDF JavaScript or automatic launch actions, and extract suspicious embedded content for analysis.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/meltedinhex/analyst-ai-pack/analyzing-malicious-pdfs
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-malicious-pdfs
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-malicious-pdfs

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/analyzing-malicious-pdfs"><img src="https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/analyzing-malicious-pdfs.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 762 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 $0.00073 $0.00762
Opus 5 $0.00036 $0.00381
Sonnet 5 $0.00015 $0.00152
Haiku 4.5 $0.00007 $0.00076

Measured 9d ago against content hash 50955fe4c890, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

analyzing-malicious-pdfs 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 9d 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-malicious-pdfs/SKILL.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Analyzing Malicious PDFs

When to Use

  • You have a suspicious PDF (often from phishing) and must determine if it is weaponized.
  • You need to find auto-executing actions, embedded JavaScript, launch actions, or embedded files.
  • You want to extract and decode suspicious streams safely.

Do not use a PDF reader to "just look" — opening in a viewer can trigger the very actions you are investigating. Parse the structure statically.

Prerequisites

  • A PDF object parser (Python, or pdfid/pdf-parser/peepdf); the sample handled inertly.

Safety & Handling

  • Never open the PDF in a graphical reader; parse the raw object structure only.
  • Defang any extracted URLs and store embedded payloads password-protected.

Workflow

Step 1: Triage the object inventory

Count high-risk keywords: /JavaScript, /JS, /OpenAction, /AA, /Launch, /EmbeddedFile, /URI, /RichMedia. Their presence (especially auto-actions) flags weaponization.

python scripts/analyst.py triage sample.pdf

Step 2: Locate auto-execution triggers

Resolve /OpenAction and /AA (additional actions) to see what runs on open, and any /Launch actions that spawn external programs.

Step 3: Extract and decode streams

Pull JavaScript and suspicious streams, applying filters (/FlateDecode, /ASCIIHexDecode) to get the cleartext; deobfuscate layered JS as needed.

Step 4: Recover payloads and IOCs

Extract embedded files and URIs; hash payloads, defang URLs, and route extracted executables to PE analysis.

Validation

  • Auto-execution triggers (/OpenAction, /AA, /Launch) are resolved to concrete actions.
  • JavaScript/streams are decoded through their filters, not left encoded.
  • Embedded payloads and URIs are extracted, hashed, and defanged.

Pitfalls

  • Opening the PDF in a reader and triggering the payload.
  • Missing object-stream (/ObjStm) compressed objects that hide the malicious content.
  • Stopping at the first JS layer when it is multiply obfuscated.

Read the full file on GitHub · 92 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. 9d ago First seen · 92 lines · 73 tokens per session scan A 50955fe4c890

Subscribe to this mod's changes

analyzing-malicious-pdfs is a skill published in the GitHub repository meltedinhex/analyst-ai-pack (22 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 73 tokens to every session and 762 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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