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analyzing-malware-sandbox-evasion-techniques — Claude Code skill

Reads Cuckoo and AnyRun behavioral reports and flags the signs that a sample spotted the sandbox and played dead.

Install into Claude Code · Skills CLI (Vercel) All methods and platforms ↓
npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-malware-sandbox-evasion-techniques -a claude-code
Open on GitHub

What analyzing-malware-sandbox-evasion-techniques does

The skill takes a behavioral report in JSON and looks through API call sequences for anti-analysis traces: timing checks via GetTickCount and QueryPerformanceCounter, queries for virtualization artifacts (registry keys, MAC address prefixes, processes such as vmtoolsd.exe), user-interaction checks through GetCursorPos and GetAsyncKeyState, and environment fingerprinting — disk size, CPU count, RAM.

A separate step compares requested sleep durations against actual ones. A gap there points to deliberate stalling, which malware uses to outlast the analysis window. The skill then scores evasion sophistication from how many techniques showed up and how varied they are, sorts them into categories, and maps them to MITRE ATT&CK T1497 sub-techniques.

Output is a JSON report listing detected techniques, the API calls behind each one, and the ATT&CK mapping. You need a Cuckoo Sandbox 2.0+ or AnyRun account, Python 3.8+ with the json library, and an exported report — there is nothing to parse without one. A sample that barely moved inside the sandbox is exactly the case worth running through this skill instead of writing off as clean.

What it helps with

  • explain why a sample stays quiet in the sandbox
  • find timing checks and inflated sleeps in a report
  • separate VM detection from ordinary system queries
  • map detected techniques to MITRE ATT&CK T1497
  • score how sophisticated the anti-analysis is

Example prompts for the agent

  • go through this AnyRun report and find sandbox evasion indicators
  • check this Cuckoo report for sleep inflation and timing checks
  • map the anti-analysis techniques in this sample to T1497 sub-techniques

How to install analyzing-malware-sandbox-evasion-techniques

1Skills CLI (Vercel)

npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-malware-sandbox-evasion-techniques -a claude-code

2Manually: put the files in place

~/.claude/skills/analyzing-malware-sandbox-evasion-techniques/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/analyzing-malware-sandbox-evasion-techniques/

Step by step, with commands for each platform: How to install skills in Claude Code: five ways

Questions about analyzing-malware-sandbox-evasion-techniques

How do I install analyzing-malware-sandbox-evasion-techniques in Claude?

Run npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-malware-sandbox-evasion-techniques -a claude-code. The skill file then sits at ~/.claude/skills/analyzing-malware-sandbox-evasion-techniques/SKILL.md.

What does analyzing-malware-sandbox-evasion-techniques do?

It parses Cuckoo and AnyRun behavioral reports for anti-analysis tricks: timing checks, virtualization artifact queries, user-interaction checks and inflated sleep. It returns a JSON report with the techniques and their MITRE ATT&CK T1497 mapping.

What do I need before running it?

A Cuckoo Sandbox 2.0+ or AnyRun account for the reports, Python 3.8+ with the json library, and a behavioral report exported as JSON.

Source text

SKILL.md · Apache-2.0
---
name: analyzing-malware-sandbox-evasion-techniques
description: Detect sandbox and VM evasion techniques in malware samples by analyzing
  timing checks, VM/hypervisor artifact queries, user-interaction checks, and sleep-inflation
  patterns from Cuckoo or AnyRun behavioral reports. Use when a sample shows no or
  minimal activity in a sandbox, when a behavioral report needs review for evasion
  indicators, or when building detections for anti-analysis techniques.
domain: cybersecurity
subdomain: malware-analysis
tags:
- sandbox-evasion
- malware-analysis
- cuckoo
- anyrun
- mitre-attack
- virtualization-detection
- behavioral-analysis
version: '1.0'
author: mahipal
license: Apache-2.0
d3fend_techniques:
- Platform Hardening
- Restore Object
- Process Analysis
- System Call Filtering
- Restore Software
nist_csf:
- DE.AE-02
- RS.AN-03
- ID.RA-01
- DE.CM-01
mitre_attack:
- T1497.001
- T1497.003
- T1480
- T1027.002
---

# Analyzing Malware Sandbox Evasion Techniques

## Overview

Sandbox evasion (MITRE ATT&CK T1497) allows malware to detect analysis environments and alter behavior to avoid detection. This skill analyzes behavioral reports from Cuckoo Sandbox and AnyRun for evasion indicators including timing-based checks (GetTickCount, QueryPerformanceCounter, sleep inflation), VM artifact detection (registry keys, MAC address prefixes, process names like vmtoolsd.exe), user interaction checks (mouse movement, keyboard input), and environment fingerprinting (disk size, CPU count, RAM). Detection rules flag samples exhibiting these behaviors for deeper manual analysis.


## When to Use

- When investigating security incidents that require analyzing malware sandbox evasion techniques
- When building detection rules or threat hunting queries for this domain
- When SOC analysts need structured procedures for this analysis type
- When validating security monitoring coverage for related attack techniques

## Prerequisites

- Cuckoo Sandbox 2.0+ or AnyRun account for behavioral analysis reports
- Python 3.8+ with json library for report parsing
- Behavioral report exports in JSON format

## Steps

1. Parse Cuckoo/AnyRun behavioral report JSON files
2. Extract API call sequences for timing-related functions
3. Identify VM artifact detection via registry queries and WMI calls
4. Detect sleep inflation by comparing requested vs actual sleep durations
5. Flag user interaction checks (GetCursorPos, GetAsyncKeyState patterns)
6. Score evasion sophistication based on technique count and diversity
7. Map detected techniques to MITRE ATT&CK T1497 sub-techniques

## Expected Output

JSON report listing detected evasion techniques with MITRE ATT&CK mapping, API call evidence, evasion sophistication score, and classification of evasion categories (timing, VM detection, user interaction, environment fingerprinting).

© mahipal · Apache-2.0 · mukul975/Anthropic-Cybersecurity-Skills

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