What it does. Detect sandbox and VM evasion techniques in malware samples by analyzing Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-malware-sandbox-evasion-techniques, or copy the skill folder into ~/.claude/skills/analyzing-malware-sandbox-evasion-techniques/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/analyzing-malware-sandbox-evasion-techniques/SKILL.md

SKILL.md (verbatim)

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).

Other files in this skill

• LICENSE
• references/api-reference.md
• scripts/agent.py

references/api-reference.md (verbatim)

Malware Sandbox Evasion Techniques API Reference

MITRE ATT&CK T1497 Sub-techniques

Cuckoo Sandbox Report JSON Structure

API Call Format

{
  "behavior": {
    "processes": [
      {
        "process_name": "malware.exe",
        "pid": 1234,
        "calls": [
          {
            "api": "GetTickCount",
            "category": "system",
            "arguments": {},
            "return": "123456789"
          }
        ]
      }
    ]
  }
}

Timing API Indicators

VM Artifact Indicators

Registry Keys

HKLM\SOFTWARE\VMware, Inc.\VMware Tools
HKLM\SOFTWARE\Oracle\VirtualBox Guest Additions
HKLM\HARDWARE\ACPI\DSDT\VBOX__
HKLM\SYSTEM\CurrentControlSet\Services\VBoxGuest

VM Process Names

vmtoolsd.exe, vmwaretray.exe    # VMware
vboxservice.exe, vboxtray.exe   # VirtualBox
qemu-ga.exe                      # QEMU
prl_tools.exe                    # Parallels

VM MAC Address Prefixes

00:0C:29  VMware
00:50:56  VMware
08:00:27  VirtualBox
00:1C:42  Parallels
52:54:00  QEMU/KVM

AnyRun Report API

Get Report

GET https://api.any.run/v1/analysis/{task_id}
Authorization: API-Key <key>

CLI Usage

python agent.py --report cuckoo_report.json --output evasion_report.json
python agent.py --report report.json --min-sleep-ms 30000

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