analyzing-malicious-vbscript-and-wsf

analyzing-malicious-vbscript-and-wsf is a skill for Claude Code, Codex from meltedinhex/analyst-ai-pack. It costs 90 tokens per session (827 once invoked), scanned A, original, Apache-2.0.

A static-analysis guide for malicious VBScript, WSF, and HTA files, which are Windows script formats often delivered through phishing. It explains how to unpack containers, decode hidden script, and inspect its actions.

In plain words
What is it for?
Use it to decode obfuscated scripts, inspect WScript.Shell or ActiveX activity, trace dropped files, and identify URLs and other indicators.
Why use it?
It reveals concealed script behavior without running Windows Script Host or the script's dropper code.

Skill for Claude CodeCodex

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

Good fit Use it to decode obfuscated scripts, inspect WScript.Shell or ActiveX activity, trace dropped files, and identify URLs and other indicators.

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Install with agentmods
npx agentmods add skills/meltedinhex/analyst-ai-pack/analyzing-malicious-vbscript-and-wsf
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-vbscript-and-wsf
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-vbscript-and-wsf

README.md
[![agentmods](https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/analyzing-malicious-vbscript-and-wsf/github.svg)](https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/analyzing-malicious-vbscript-and-wsf)
Your own site
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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.

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Your own site · 80×15
<a href="https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/analyzing-malicious-vbscript-and-wsf"><img src="https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/analyzing-malicious-vbscript-and-wsf.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 90 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 827 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 $0.00090 $0.00827
Opus 5 $0.00045 $0.00413
Sonnet 5 $0.00018 $0.00165
Haiku 4.5 $0.00009 $0.00083

Measured 9d ago against content hash bac9d14e8e96, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

analyzing-malicious-vbscript-and-wsf 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-vbscript-and-wsf/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 VBScript and WSF

When to Use

  • You have a .vbs, .wsf, or .hta delivered via phishing and need its real behavior.
  • You must decode VBScript.Encode-obfuscated script (the #@~^ marker) or string obfuscation.
  • You are identifying WScript.Shell/ActiveX-based dropper actions and IOCs.

Do not use wscript/cscript/mshta to run the script for analysis — that executes the dropper. Decode and read it statically.

Prerequisites

  • A static decoder (Python) or a script sandbox; the sample handled inertly in the lab.

Safety & Handling

  • Never run the script with Windows Script Host (wscript/cscript/mshta).
  • Defang recovered URLs; store dropped payloads password-protected.

Workflow

Step 1: Parse the container

For WSF, parse the XML <job>/<script> elements (a WSF can bundle multiple languages). For HTA, separate the HTML wrapper from the <script> body.

python scripts/analyst.py analyze sample.wsf

Step 2: Decode VBScript.Encode

If you see the #@~^ header, decode the Microsoft Script Encoder stream back to source.

Step 3: Unroll string obfuscation

Resolve Chr()/Asc() builds, string concatenation, and Replace()-based deobfuscators to reveal commands and URLs.

Step 4: Identify dropper actions and IOCs

Find CreateObject("WScript.Shell"), Run/Exec, ADODB/MSXML download patterns, and PowerShell hand-offs; recover URLs/paths, defang, and route payloads onward.

Validation

  • WSF/HTA containers are decomposed into their script bodies (all jobs/languages).
  • VBScript.Encode streams are decoded to readable source.
  • Dropper actions and IOCs are recovered without executing the script.

Pitfalls

  • Executing with wscript/mshta to "see" behavior, infecting the host.
  • Missing one <script> block in a multi-job WSF.
  • Overlooking the #@~^ encoded section and analyzing only the cleartext stub.

References

  • See references/api-reference.md for the WSF/VBScript decoder.
  • Windows Script Host docs and the Script Encoder format (linked in frontmatter).

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 · 90 tokens per session scan A bac9d14e8e96

Subscribe to this mod's changes

analyzing-malicious-vbscript-and-wsf is a skill published in the GitHub repository meltedinhex/analyst-ai-pack (22 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 90 tokens to every session and 827 once invoked, about $0.0005 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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