README.md

---
pretty_name: MELD-DS-448
license: cc-by-nc-sa-4.0
language:
- en
tags:
- malware
- cybersecurity
- CAPE
- Windows
size_categories:
- 10K<n<100K
task_categories:
- other
---

# Appendix: MELD-DS-448 Dataset Overview

## Dataset Overview

MELD-DS-448 contains **26,166 malicious samples** spanning **448 distinct malware families** collected from April 2020 to August 2025. All samples are uniquely identified by SHA-256 hashes and include precise "First Seen" timestamps.

**Family Distribution Characteristics**: The dataset exhibits a typical long-tail distribution, with 35.7% singleton families (only 1 sample) and 64.7% small-scale families (≤5 samples). Head concentration is significant, with the top 5 families covering 30.1% of samples and the top 10 families covering 41.5% of samples. Major families include LummaStealer (2,966 samples, 11.3%), Formbook (2,091 samples, 8.0%), SnakeKeylogger (1,045 samples, 4.0%), and others.

**Temporal Evolution Patterns**: Samples are primarily concentrated in 2024-2025 (96.8%), with the majority appearing in 2025 (77.1% of samples). The temporal distribution shows rapid growth in recent years, with 2024 contributing 19.7% and earlier years contributing minimal samples. This demonstrates the rapid evolution characteristics of contemporary malware ecosystems.

### Dataset Statistical Overview

| Metric | Value | Description |
|--------|-------|-------------|
| **Total Families** | 448 | Total number of distinct malware families |
| **Total Samples** | 26,166 | Total number of malicious samples |
| **Avg Samples/Family** | 58.4 | Average samples per family |
| **Sample Count Median** | 3 | Median of family sample counts |
| **Singleton Families** | 160 (35.7%) | Families with only 1 sample |
| **Small Families** | 290 (64.7%) | Families with ≤5 samples |
| **Large Families** | 36 (8.0%) | Families with ≥100 samples |
| **Top 5 Coverage** | 30.1% | Sample coverage by top 5 families |
| **Top 10 Coverage** | 41.5% | Sample coverage by top 10 families |

### Annual Evolution Statistics

| Year | Active Families | Samples | Percentage |
|------|----------------|---------|------------|
| 2020 | - | 6 | 0.0% |
| 2021 | - | 258 | 1.0% |
| 2022 | - | 343 | 1.3% |
| 2023 | - | 227 | 0.9% |
| 2024 | - | 5,146 | 19.7% |
| 2025 | - | 20,186 | 77.1% |

## Standardized Analysis Artifacts

Each sample in MELD-DS-448 provides four types of standardized analysis data generated through unified CAPE Sandbox analysis in virtualized Windows 10 x64 (22H2) environments:

**1. CAPE JSON Reports** - Complete structured analysis results containing behavioral indicators, network activities, file system operations, registry modifications, and process execution traces, as the original analysis reports from CAPEv2.

**2. Markdown Structured Reports** - Converting CAPE JSON reports into LLM-friendly structured Markdown format containing complete behavioral events, API call patterns, process tree information, and temporal analysis. These reports are specifically designed for large language model processing and understanding.

**3. API Call Sequences** - Chronologically ordered sequences of Windows API function calls captured during dynamic execution, including parameters and return values, converted from CAPEv2's JSON reports. These sequences enable fine-grained behavioral modeling and sequence-based machine learning approaches.

**4. ASM Disassembly Files** - Static disassembly output providing low-level instruction sequences and control flow information. These artifacts support static analysis techniques and hybrid approaches combining static and dynamic features.

**Note on ASM File Coverage**: Out of 26,166 total samples, 361 samples (1.38%) do not have corresponding ASM disassembly files due to disassembly process failures during reverse engineering analysis. These missing files are documented in `asm_loss.csv` for reference. The remaining 25,805 samples (98.62%) have complete ASM disassembly data available.

## Data Quality and Coverage

All 26,166 samples (100% coverage) include complete metadata and three primary analysis artifact types (CAPE JSON reports, Markdown reports, and API call sequences). ASM disassembly files are available for 25,805 samples (98.62%), with 361 samples missing ASM files due to disassembly process failures. The dataset ensures sample uniqueness through SHA-256 deduplication and maintains temporal consistency with verified timestamps. File sizes range from 87.3 KB to 301.3 MB (median: 3.6 MB), with the complete dataset totaling 479 GB of analysis artifacts and metadata.

## Dataset File Structure

The dataset files are organized in the `Dataset/` directory with large files split into volumes for easier download and Git LFS compatibility:

### File Restoration Instructions

Due to file size limitations, large dataset files have been split into 4GB volumes. To restore the original files, use the following commands:

**1. ASM Disassembly Files (27GB total)**
```bash
7z x asm.7z.001
```

**2. API Call Sequences (8.9GB total)**  
```bash
7z x api_sequence.7z.001
```

**3. CAPE JSON Reports (8.5GB total)**
```bash
7z x cape_reports.7z.001
```

**4. Markdown Reports (67MB - no splitting needed)**
- File: `cape_reports_malicious_md.7z`
- Can be extracted directly: `7z x cape_reports_malicious_md.7z`

### Requirements
- **7-Zip**: Required for extracting split archives
- **Disk Space**: Ensure at least 500GB free space for extraction
- **Memory**: Recommended 8GB+ RAM for processing large files

## License

This project is licensed under the [CC BY-NC-SA 4.0](https://creativecommons.org/licenses/by-nc-sa/4.0/) (Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International) license.