Malware Analysis Fundamentals: From Static to Dynamic

Published on January 10, 2024

Introduction

Malware analysis is a critical skill in cybersecurity that involves examining malicious software to understand its behavior, capabilities, and potential impact. This guide covers the fundamental approaches to malware analysis.

Analysis Types

Static Analysis

Static analysis examines malware without executing it:

• File structure analysis
• String extraction
• Import/Export analysis
• Code disassembly
• YARA rule creation

Dynamic Analysis

Dynamic analysis involves running malware in controlled environments:

• Behavioral monitoring
• Network traffic analysis
• System call monitoring
• Memory analysis
• Registry monitoring

Tools of the Trade

Static Analysis Tools

# PE file analysis
strings malware.exe
file malware.exe
peid malware.exe

# Disassembly
objdump -d malware.exe
radare2 malware.exe

Dynamic Analysis Tools

• Cuckoo Sandbox: Automated malware analysis
• Process Monitor: System call monitoring
• Wireshark: Network traffic analysis
• Volatility: Memory forensics
• Process Hacker: Process monitoring

Analysis Workflow

1. Initial Assessment

import pefile

pe = pefile.PE('malware.exe')
print(f"Architecture: {pe.OPTIONAL_HEADER.Magic}")
print(f"Entry Point: {pe.OPTIONAL_HEADER.AddressOfEntryPoint}")
print(f"Subsystem: {pe.OPTIONAL_HEADER.Subsystem}")

2. String Analysis

Extract and analyze strings for:

• URLs and IP addresses
• File paths
• Registry keys
• API calls
• Encryption keys

3. Import Analysis

Identify imported functions:

• Network communication APIs
• File system operations
• Registry manipulation
• Process creation
• Anti-debugging techniques

4. Behavioral Analysis

Monitor for:

• File system changes
• Registry modifications
• Network connections
• Process creation
• Service installation

Common Malware Families

Ransomware

• File encryption
• Ransom notes
• Network propagation
• Anti-recovery mechanisms

Trojans

• Backdoor functionality
• Data exfiltration
• Keylogging capabilities
• Remote control features

Rootkits

• System-level persistence
• Anti-detection mechanisms
• Kernel-level modifications
• Boot sector infection

Analysis Environment Setup

Virtual Machine Configuration

# Snapshot management
VBoxManage snapshot "MalwareVM" take "CleanState"
VBoxManage snapshot "MalwareVM" restore "CleanState"

# Network isolation
VBoxManage modifyvm "MalwareVM" --nic1 hostonly

Monitoring Tools

• Process Monitor: Real-time system monitoring
• API Monitor: API call interception
• Regshot: Registry change detection
• Wireshark: Network traffic capture

YARA Rules

Create custom detection rules:

rule Malware_Family_Example {
    meta:
        description = "Detects specific malware family"
        author = "Uddip Ranjan Das"
        date = "2024-01-10"
    
    strings:
        $s1 = "malicious_string_1"
        $s2 = "malicious_string_2"
        $s3 = "malicious_string_3"
    
    condition:
        2 of them
}

Reporting

Analysis Report Structure

1. Executive Summary
   • Malware type and family
   • Impact assessment
   • Key findings
2. Technical Details
   • File characteristics
   • Behavioral analysis
   • Network indicators
   • Persistence mechanisms
3. IOCs (Indicators of Compromise)
   • File hashes
   • IP addresses
   • Domain names
   • Registry keys
4. Mitigation Strategies
   • Detection rules
   • Prevention measures
   • Response procedures

Best Practices

1. Isolation: Always analyze malware in isolated environments
2. Documentation: Maintain detailed analysis notes
3. Automation: Use automated tools for repetitive tasks
4. Collaboration: Share findings with the security community
5. Continuous Learning: Stay updated with new malware techniques

Conclusion

Malware analysis is both an art and a science. Success requires technical expertise, analytical thinking, and continuous learning. The key is to understand not just what malware does, but why it does it and how to prevent similar attacks.

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